Minivans

Chrysler/Dodge Minivan Powertrain and Chassis Information

Engine Systems

The engine plays a vital role in vehicle responsiveness, driveability, and fuel economy. For a minivan, these ingredients come from a broad torque curve, rather from high peaks of torque and power.

Quality and reliability are a primary ingredient that keeps customers as repeat buyers. The original minivan engines could be troublesome as they grew older; the 3.0 V6 had valve seal leaks (fixed in the early 1990s), and the 2.2 and 2.5 four-cylinders did not have enough power for the minivan's weight. Minivan engines are expected to provide best-in-class quality, reliability and refinement. For the engine, that means both long lasting and utterly reliable - an engine that will never stop running or fail to start. It also means quietness and freedom from leaks. Refinement is reflected in, among other things, a smooth idle and pleasant, unobtrusive sound quality under all operating conditions.

The 3.3 and 3.8 engines had to be adapted to the new 1996 minivan engine compartment include a revised throttle body location, a new right (rearward in the vehicle) exhaust manifold to provide a common outlet location with other new minivan engines and a new cross-over pipe.

1996 engines - performance and fuel economy

For improved performance of the 3.3 and 3.8-Liter OHV SMPI V-6 engines, a significantly broader torque curve is accompanied by a higher torque peak. Torque is increased substantially over 1995 levels between 2400 and 4800 rpm on both engines. The broad torque curves provide maximum customer perception of performance and also contribute to good fuel economy. Changes for better torque and fuel economy include the following items:

  • Re-tuned intake manifold with longer - 16-inch (406 mm) - primary runners to increase torque
  • Tuned, low-restriction induction system
  • Reduced exhaust system back pressure
  • Coated pistons to reduce friction (late availability)
  • Calibration of the ignition and fuel injection systems for mid-range torque and fuel economy
  • Addition of a knock sensor to the ignition system, allowing maximum spark advance under all conditions for high fuel economy, brisk response and high power while protecting against engine damaging knock
  • Reduced idle speed for greater fuel economy

1996 power ratings:

  • The 3.3 gets Ratings of these engines are as follows:
    Engine Rating Factor Rating
    158 bhp (118 kW) @ 4850 rpm and 203 lb-ft (278 narrow) @ 3250 rpm.
  • The 3.8 gets 166 bhp (124 kW) @ 4300 rpm and 227 lb-ft (308 N*m) @ 3100 rpm.

Components and sub-systems throughout the engine have been upgraded to assure operation for 10 years or 100,000 miles (160,000 km) without major service. Specifically, valves, piston rings and bearings are made from premium materials. Platinum-tipped spark plugs are standard on 3.3 and 3.8-liter engines. They last 100,000 miles (160,000 km) under normal driving conditions.

3.0-Liter SOHC SMPI V-6 Engine

This engine is sourced from Mitsubishi. It was the first V6 to be featured in Chrysler minivans, starting around the same time as the 2.2 liter turbocharged engines. Power and torque of the 3.0-liter engine benefit from the tuned, low restriction air induction system and reduced back pressure common to all 1996 minivan engines. Peak power was increased in 1996 by 8 horsepower (6 kW) and torque is up 3 lb-ft (4 N-m) to 150 bhp (112 kW) @ 5200 rpm, and 176 lb-ft (239 N-m) @4000 rpm. (These ratings are similar to the 2.4 liter four-cylinder!). In 1996, the right (rearward in the vehicle) exhaust manifold was redesigned to provide a common outlet location with other 1996 minivan engines.

2.4-Liter DOHC SMPI I-4 Engine

A 2.4-liter DOHC SMPI I-4 engine is new to Chrysler minivans but very similar to the 2.4-liter engine first introduced in the Dodge Stratus. Changes from Stratus are primarily associated with fitting the engine into to the minivan engine compartment. Compared to the 2.5- liter four-cylinder engine used previously, the new engine has far more power and torque - approaching the levels of the 3.0-liter V-6. While substantially increasing acceleration capability, the 2.4-liter engine maintains the fuel economy of its predecessor. Because of increased performance without loss of fuel economy, the 2.4-liter engine is expected to find greater market acceptance than its predecessor.

Performance features include a 16-valve double overhead camshaft cylinder head, a tuned aluminum intake manifold and a tuned, low restriction air induction system. A high compression ratio, (9.4:1), also contributes to the outstanding power output. The 2.4-liter engine is also substantially quieter than its predecessor. See 2.4-Liter I-4 Engine under Powertrain Noise Reduction in the Quietness section.

The 2.4-liter engine was, in the 1990s, available with either three-speed or electronically controlled four-speed overdrive automatic transaxles.

The 2.4-liter engine has a broad, flat torque curve with 90% of peak torque available between 2000 and 5000 rpm. The engine reaches peak power at a relatively low speed for a DOHC engine of 4000 rpm. The large "breathing" capacity of the DOHC head has been directed toward achieving high torque and fuel economy through camshaft design and intake manifold tuning. High torque for hauling heavy loads and good fuel economy, rather than peak performance, are the engine attributes that minivan buyers seek.

  • 150 bhp (112 kW) @ 4800 rpm
  • 167 lb-ft (226 N*m) @ 4000 rpm

Relative performance of the 2.4-liter engine and its predecessor (and with the three-speed automatic):

2.4 L 4-speed vs... 2.4 L 3-speed 2.4 L 3-speed
5 second distance +5.0% +9.5%
0 - 60 mph +22.0% +19.3%
40-60 mph (in gear) +22.0% + 25.8%
3rd gear grade @ 55 mph +12.0% +50%
EPA gas mileage: city/highway -1 mpg / same same/same
  • Displacement 148.2 cu in (2429 cc)
  • Bore 3.44 (87.5)
  • Stroke 3.98 (101)
  • Bore-to-stroke ratio 0.87
  • Bore spacing 3.78 (96)
  • Block length 16.43 (417.3)
  • Block height 9.36 (237.8)
  • Rod length 5.94 (151)
  • Piston height 1.43 (36.3)
  • Connecting rod L/R 2.99
  • Compression ratio 9.4:1

* All dimensions are in inches (millimeters) unless otherwise noted.

2.4 liter engine - cylinder Head

The cylinder head is a low profile aluminum casting with pent-roof combustion chambers that house four valves per cylinder.
The valve included angle is 48 degrees, allowing large valves. Dual camshafts run in six bearings that are machined in the head base material and have removable caps. Powdered metal valve seat inserts and valve guides are pressed into the head. Spark plugs thread into the center of the combustion chamber through wells cast into the head.

Ports from each valve merge in the head, leading to a single branch (runner) in their respective manifolds. To provide turbulence in the cylinders that contributes to the rapid combustion necessary for low emissions and efficient operation on regular-grade gasoline, the ports cause incoming air to "tumble" from top to bottom of the cylinders. The degree of tumbling action was balanced against the conflicting need for high air flow to obtain high power output.

Cylinder Head Cover

Made of die cast aluminum, the cylinder head cover features an isolated mounting which uses O-ring type, silicone perimeter gasket. The distributorless ignition coil-mount is built into the cover. The PCV system is also integral with the cylinder head cover.

Cylinder Block

The block is cast iron with a cast iron ladder-type bedplate.
It is 9.36 inches (237.8 mm) high. Bore spacing of 3.78 inches (96 mm)
allows coolant to flow around all cylinders to assure long head-gasket
life. To reduce radiated noise, the block and bedplate have no flat or
single-curvature outer surfaces. Lower surfaces provide a constant
clearance to moving parts and upper surfaces conform the water jacket
contours.
The bedplate is made up of a perimeter wall and transverse webs that
support the crankshaft, giving structural rigidity for durability at
high rpm's and for quiet operation. The bedplate also provides a flat
sealing surface for the oil pan.
The oil gallery is located on the right side of the block with dual
feeds to each main bearing.
The water pump housing and rear crankshaft seal housing are cast
integral with the block.

Intake Manifold

The two-piece, cast aluminum manifold has a runner length of 17.7
inches (450 mm). The intake manifold combines tuned individual runners
for each cylinder extending from an integral plenum chamber. The
runners curve backward above the cylinder head cover to clear the hood.
The manifold is cast in two pieces, separated in the middle of the
runner curvature, for ease of manufacture. The throttle body mounting
flange is at nearly the same location as the V-6 engines to simplify
linkage installation and intake duct routing. The upper half of the
manifold includes a raised-letter logo - "2.4 L DOHC" - cast into the
top surface.

Exhaust Manifold

Made of cast nodular iron, the exhaust manifold has a 0.14 inch (3.5
mm) wall thickness with four-into-one runner design. It provides a
common outlet flange location with the V-6 engines to simplify the
exhaust system.

Valve Train

Dual overhead camshafts actuate four valves per cylinder. Valve
diameters are 1.37 inch (34.8 mm) intake and 1.20 inch (30.5 mm)
exhaust. All valves have 0.25 inch (6 mm) chrome plated stems. Valves
have a 48-degree included angle. The exhaust valves are on the right
(rearward) side of the head. Each valve is operated by an end-pivot
rocker arm that has a 0.67 inch (17 mm) roller cam follower to reduce
low speed friction and cam wear. Rockers pivot on inboard-mounted,
fixed hydraulic lash adjusters. Single valve springs provide control of
valve actuation to 6200 rpm.
Camshafts of post-hardened nodular cast iron provide a 236 degree
intake duration and a 240 degree exhaust duration. The intake cam
centerline is 113 degrees ATDC, the exhaust is 110 degrees BTDC, with 15
degrees of overlap. Intake valve lift is 0.33 inches (8.25 mm) and
exhaust valve lift is 0.26 inches (6.5 mm).
A state-of-the art cog belt drives the camshafts. The belt system
is designed to last the life of the vehicle without adjustment or
replacement. High belt loads usually associated with operating were
minimized by a systems design approach. A hydraulic automatic tensioner
forces an idler pulley against the back of the belt, maintaining proper
tension for the life of the vehicle.
A three-piece molded plastic cover, completely encloses the belt to
minimize belt noise and protect the belt from damage by foreign matter.
Pistons

Cast aluminum, single-size pistons weigh 11.7 ounces (332 grams) each.
The pop-up top with valve cut outs allows broken-belt clearance. Piston
pin diameter is 0.87 inches (22 mm); weight is 4.16 ounces (118 grams).
Piston pins are held in place by press fit to the connecting rods.

Connecting Rods

The rods and caps are initially formed as one-piece powdered-metal
precision forgings. Powdered-metal rods and caps are lighter than
conventional steel forgings. The reduced weight results from good
dimensional control that is inherent in the process and from elimination
of the small-end balance pad. Lighter rods benefit the vehicle by
providing smooth operation at high rpm.
The cap is separated from the rod in a unique cracking process.
Uneven mating surfaces which result give good rod-to-cap alignment
during assembly. To make assembly easy and to reduce weight, the 9 mm
cap mounting bolts thread directly into the rod, instead of into
separate nuts.

Crankshaft

Cast of nodular iron, the lightweight crankshaft has eight
counterweights. Counterweights straddle each crank pin to balance the
bearing loads within each bay for smooth, quiet operation. Main bearing
diameter is 2.36 inches (60 mm), rod bearing diameter is 1.97 inches (50
mm). The crankshaft main bearing journals are 1.0 inch (25.5 mm) wide
for low friction.
A torsional vibration damper is used. The damper has two poly-V
pulleys that drive accessories.

Balance Shafts

The 2.4-liter engine operates very smoothly because a system of
counter-rotating balance shafts counteracts second-order unbalance, the
predominant cause of four-cylinder engine vibration.
The two counter-rotating, eccentric balance shafts, interconnected
by gears, are driven by a short chain from the crankshaft. They turn at
two times engine speed to offset the reciprocating mass of the pistons
and connecting rods and to achieve the desired balancing effect. The
balance shafts are enclosed in an aluminum housing mounted beneath the
crankshaft in the oil pan. The housing is bolted to the bottom of the
main bearing webs of the bedplate and rests in the oil supply. When the
engine is running, the balance shafts pump oil out of the housing to
minimize parasitic drag which could occur if the shafts spun in the oil.

Bearings

The camshafts need no bearing inserts. They operate directly in the
cylinder head. Main and rod bearings have bi-metal inserts.

Lubrication System

The powdered metal gerotor oil pump mounts in the front of the block
and is driven by the crankshaft to reduce noise and complexity. The
system that returns oil from the head is designed to prevent aeration
during high-rpm running. The block is inclined to the right (rearward
in the car) to allow the oil to drain from the head along the right face
of the block. The crankcase is ventilated through an opening on the
left side of the head. Oil capacity is 4 quarts (3.8 L) plus filter.
SAE 5W-30 oil, grade SG/SH is recommended. A half-quart oil filter
mounts horizontally to an extension of the oil pump body. The oil pan
is stamped from sound-damping metal-plastic-metal laminate.

Fuel Injection System

Returnless, sequential multi-port injection (SMPI) uses four dual-
spray injectors to provide balanced fuel delivery to all cylinders.
Injectors direct separate sprays to the intake valves. A small slot in
the top of each intake port allows proper location of the injector
spray. Sequential injection improves throttle response and overall
driveability compared to single-point injection.
The injection system is returnless to reduce complexity compared to
customary systems. This very important emission-control innovation also
drastically limits the creation of fuel vapors which must be captured by
the evaporative emission-control system. The fuel return line is
eliminated and the electronic control has been refined to compensate for
variations in injection pressure that result. Only the fuel to be used
is delivered to the engine. There's none left over that needs to be
returned to the fuel tank.
Variable injection timing is used to provide good idle quality
without compromising performance and fuel economy. The fuel injection
system uses the same sensors as the ignition system to provide speed,
timing and cylinder-selection data. These direct acting sensors provide
more accurate response than a conventional distributor. In addition,
intake charge temperature and coolant temperature are used to fine tune
injection rate for economy and performance.
The throttle body has a 2.05-inch (52 mm) bore to minimize
restriction at high rpm.

Ignition System

The 2.4-liter engine features a direct ignition system (DIS), which
offers several key advantages over distributor systems:
-- Reduced engine length (no distributor drive)
-- Reduced engine complexity (no distributor or related parts)
-- Direct information to control the fuel injection system
-- Quick starts because camshaft and crankshaft sensors give early
notice of which cylinder is ready for injection and ignition
-- Accurate firing because ignition and fuel injection timing signals
come directly from the crankshaft and camshaft
-- Smooth idle because timing variation is reduced
-- Quick throttle response
-- Low maintenance
-- High reliability because of proven sensors

Two sensors (one for crankshaft timing, the other for camshaft
reference) provide the data to operate the ignition system.
The crankshaft sensor, inserted through the side of the block,
senses two patterns of four slots each in the number 2 counterweight,
180 degrees apart. The slots feed data for engine speed and timing
calculations. Their positions on the crankshaft establish engine basic
timing. The fact that they sense directly from the crankshaft means
more accuracy than conventional systems. Individual slots are spaced 20
degrees apart. Spark advance and injection timing are computed from
these points. One slot, called the "signature" slot, is 60 degrees
wide; the others are approximately 5 degrees wide. The sensor output
that comes from the "signature" slot combines with the signal from the
camshaft sensor to determine the cylinder ready for fuel and ignition.
The camshaft sensor is mounted on the outside rear of the cylinder
head. It is triggered by a ring magnet in the end of the camshaft. The
magnet's four poles are arranged at 150-degree and 210-degree intervals.
Their relationship to the signature slot is established in less than one
turn of the crankshaft, allowing injection and ignition to begin.
A Chrysler-patented two-wire knock sensor is more costly than a
conventional single wire sensor, but its signal is clearer. In
addition, it is more sensitive, allowing maximum spark advance under all
conditions for high fuel economy, brisk response and high power without
producing engine-damaging knock.
The four-lead direct-ignition coil is mounted on the cylinder head
cover. As a result, secondary-wire leads are short.

Cooling System and Water Pump

To reduce complexity, the base of the water pump housing is part of
the block. The body of the pump is die cast aluminum, bolted to the
front of the block. The pump is driven by the timing belt.

Crankcase Ventilation System

To minimize oil pullover at high rpm, the crankcase ventilation
system includes an oil separator in the cylinder head cover. The
separator has baffles that inhibit the flow of oil to the intake
manifold. Oil drains out of the baffling on a long, narrow plate pinned
to the inside of the cover.

Accessory Drive

The alternator and air conditioner compressor are driven by a "poly
V" belt from the crankshaft damper. Belt tension is adjusted with a
pivoting alternator bracket that has a jack screw for easy adjustment.
The power steering pump is driven by a separate poly-V belt that is
adjusted by pivoting the pump mounting bracket. The belts are protected
from road splash and debris by a large molded plastic shield.

Quality and Reliability

The 2.4-liter engine is designed to run for 100,000 miles (160,000
km) without major service. This has required use of top-quality valve,
piston ring and bearing materials. It also required that the camshaft
drive belt be upgraded over that used on the 2.5-liter engine in 1995.

Air Induction System

A tuned air induction system for increased mid-range power and
torque on all 1996 minivan engines. The volume and length of the inlet
duct between throttle body and air cleaner - called a "zip" tube - are
tuned to increase mid-range torque. This has the effect of removing a
dip in the torque curve that is associated with tuning of the intake
manifold runners. The zip tube is tuned in conjunction with the air
induction resonator.
The air induction system is larger than that on prior models,
reducing inlet air flow restriction by over 20% for increased power and
torque. The air cleaner is part of the air induction system and is
common to all engines. It includes a low-restriction panel-type filter
element. For increased performance in hot weather, ambient air is
ducted to the air cleaner. The duct passes through the left headlight
mounting panel and draws air from behind the light assembly. Because a
large air cleaner is used to minimize air flow restriction, the filter
element replacement interval exceeds 30,000 miles (48,000 km).
See also, Air Induction Resonators under Powertrain Noise Reduction
in the Quietness section.

Transaxles

41TE Electronically Controlled Four-Speed Overdrive Transaxle

The 41TE transaxle available on 1996 minivans is a refinement of the
1995 minivan transaxle. It is the only automatic transaxle with adaptive
controls that use real-time feed-back for all shifts available in a
minivan. During a shift, the transaxle can modulate hydraulic pressure
143 times per second - 14 adjustments in the time it takes to blink
(approximately 0.1 second) - to assure smooth operation. The 41TE
transaxle is simpler, lighter and more compact than competitive
transaxles of similar capacity. Basic features are unchanged from 1995.
Customer requirements regarding the transaxle revolve primarily around
proper function. A number of internal mechanical refinements increase
the durability of the transaxle in response to greater customer
expectations. Transaxle operation can also have a significant effect on
quietness and driving experience that provides a sense of confidence.
Additional refinements are directed toward meeting these requirements.
See also Transaxle Control Module under
Electrical and Electronic Systems below.

31TH Three-Speed Automatic Transaxle

General Information
Several internal changes increase durability of the 31TH transaxle to
the corporate 100,000 mile (160,000 km) standard.

Torque Converter For 2.4-Liter Engine

The torque characteristics of the 2.4-liter engine require a new
torque converter that is tailored to the engine. The converter uses a
revised impeller blade shape to reduce converter slippage for improved
fuel economy during city driving. It also includes a converter clutch
to eliminate slippage during highway driving.

Torque Converter Refinements

Torque converters have been refined to increase durability and
driveability. The following changes have been made:
-- All converters use bonded friction disc in the converter clutch. This
construction is more durable than the previous construction and
provides smoother engagement for better driveability.
-- A more durable thrust washer is used between stator and turbine on
all converters.
-- With 2.4 and 3.0-liter engines, a needle roller bearing handles
thrust loads between the impeller and stator.
-- With 3.3 and 3.8-liter engines, more durable converter clutch damper
springs are used.

Torque Converter Drive Plates

Drive Plate With 2.4-Liter Engine - A state-of-the-art one-piece
torque converter drive plate minimizes starter engagement noise through
improved concentricity and more accurate teeth than previous drive
plates. New technology, being used for the first time by Chrysler to
manufacture drive plates, forms the ring gear teeth into the flanged
outer diameter of the drive plate stamping. This manufacturing process
also reduces weight and cost compared to the previous welded and
broached ring gear which was welded to a stamped plate.

Drive Plate With V-6 Engines - All V-6 engines use a lightweight
drive plate with lightening holes and a thinner starter ring gear.

All-Wheel Drive System

The all-wheel drive system, which is functionally unchanged, will
not be available at introduction. A new viscous coupling and an
aluminum torque tube reduce system weight by 9.2 pounds (4.2 kg). As in
previous years, it is available only on long wheelbase models.

Powertrain Electrical And Electronic Systems

Transaxle Control Module
General Information
The third generation TCM (Transmission Control Module), EATX III,
used with the 41TE transaxle includes these new features:
-- Full implementation of OBD II (On-Board Diagnostics, second phase)
-- Increased computing speed and power that allows faster program
execution by using a 16-bit rather than 8-bit data bus
-- Double the electronically-programmed memory capacity - to 64k x 16
bytes from 64k x bytes
These added capabilities provide better shift quality by altering
shift characteristics based on engine and transmission temperature.
This affects shifting during warm up and when engine and/or transmission
are overheated. In conjunction with a new data link to the PCM, it also
allows engine torque management.
See also Engine Torque Management under
Powertrain Control Module below.
EATX III also provides a vehicle-speed signal for use by the PCM as
did EATX II. The PCM in turn forwards the information to the instrument
cluster for operation of the speedometer and odometer.

Electronic Display Logic
With the 41TE automatic transaxle, the transaxle gear indicator
("PRNDL") on the instrument panel is an electronic display that receives
its signal from the TCM. Because the signal is verified by the TCM, no
indicator adjustment is required and the possibility of a vague or
erroneous reading is virtually eliminated.
See also Computer Systems Network under Electrical
and Electronic Systems in the Body section.
and Instrument Cluster and Information Center
under Instrument Panel and Instrument Cluster
in the Body Interior section.

Interactive Automatic Speed Control
For increased driver confidence and comfort, interactive automatic
speed control provides improved operation in circumstances where the
system could not control speed or customers were uneasy about using
speed control. Interactive automatic speed control also avoids
unnecessary shifting for smoother, quieter operation and, when
downshifts are required, makes the shifts smoother than competitive
systems. Interactive automatic speed control is available only with
41TE automatic transaxle. "Interactive" means that the feature is
accomplished through communication between the PCM (Powertrain Control
Module) and TCM. It is included in the control software and consists of
the following functions:Overspeed Reduction - Overspeed reduction helps
maintain vehicle speed at the selected set point when descending a
grade. The TCM first senses that the speed control is set. If the set
speed is exceeded by more than 3 mph (5 km/hr) and the throttle is
closed, the TCM causes the transaxle to down shift to Third gear. After
the downshift, the automatic speed control continues its normal
operation. Conditions leading to a return to overdrive after the
descent is complete are monitored to assure that transaxle cycling will
not occur.

Downshift Delay - To reduce the number and frequency of downshifts
when operating in hilly country and to reduce engine "flare" noise when
a downshift is necessary, downshift delay logic has been added. A
downshift is delayed or avoided by allowing the automatic speed control
unit to provide much larger throttle openings than in the past. Only if
vehicle speed drops more than 2-3 mph below the set speed and continues
to fall does a downshift occur. When the steepness of the grade demands
a downshift, engine flare is eliminated by reducing the throttle opening
as the shift is made. Automatic speed control quickly resumes throttle
control to maintain speed. The amount of throttle opening reduction is
calibrated to provide approximately the same transmission output torque
after the downshift as before it.
Grade "Hunting" Prevention Refinement
Grade "hunting" prevention - the ability of the transmission logic
to delay an upshift on a grade if the engine does not have sufficient
power to maintain speed in the higher gear - has been expanded to
include 2-3 shifts as well as 3-4 shifts. The 3-2 downshift and the
potential for hunting between gears occurs with a heavily loaded vehicle
or on steep grades. When hunting occurs, it is very objectionable
because shifts are frequent and accompanied by large changes in noise
and acceleration. The system also compensates for the loss of engine
output that occurs at high altitude through communication with the PCM.
Grade hunting prevention works with automatic speed control as well as
normal driver control.

Powertrain Control Module
General Information
New minivans use SBEC III (single board engine controller, version
3), the newest version of the corporate PCM (Powertrain Control Module).
It offers the following new features:
-- Digital Control For Engine Cooling Fans - The control software
monitors coolant temperature and air conditioning system head
pressure to determine fan speed. For both parameters it adds the
difference and the rate of change between target and actual values of
these parameters to determine the speed at which the fans should
operate. If the coolant temperature and/or air conditioning system
head pressure is below target but the rate of change indicates that
it will soon exceed the target, the fans are started or speed is
increased. With this control strategy, it is possible to operate the
air conditioning system with the fans off - a condition not
previously available on any Chrysler vehicle. Power is supplied in
pulses that vary from 30 to 100% of continuous operation - 30% "on"
time produces a speed about half the maximum speed. Power is
delivered to the fans through new electronic relays that are capable
of cycling continuously where conventional mechanical relays are not.
To assure ample life, they are attached directly to underhood sheet
metal which helps to dissipate the heat created by the high switching
rate. These electronic relays also eliminate the sometimes-audible
click associated with conventional relay control.
See also Cooling System in the Chassis section.
-- Full implementation of OBD II
-- Increased computing speed and power that allows faster program
execution
-- Quadruple the electronically-programmed memory capacity o to 64k x 16
bytes from 32k x 8 bytes
See also On-Board Diagnostics under Vehicle Environmental
Features in the Environmental Protection section.

Engine Torque Management
Engine torque management is used with 2.4, 3.3 and 3.8-liter engines
equipped with the 41TE transaxle to give quicker, smoother shifts than
would be possible without this feature. Torque management affects two
separate operating conditions: shift torque and stall torque.
Sophisticated shift torque management replaces the rudimentary spark
advance-based system that was introduced on minivans in 1994. It
improves shift quality and enhances transaxle durability. The new
system uses a selective fuel shut off to achieve a 50% reduction in
engine output torque and a 30% reduction in energy dissipation during
shifts. It requires precise interactive communication between the PCM
and TCM for successful completion.
Stall torque management, which was also introduced on 1991 minivans,
protects the transaxle against excessive torque during standing start
acceleration with a heavy load, while climbing a grade or when brake-
torquing - depressing the brake and holding the throttle open. The PCM
controls the engine rpm-to-vehicle speed relationship below 7-8 mph to
prevent excessive torque output by retarding the ignition timing. This
has virtually no effect on acceleration and does not occur under most
driving conditions.

Starter Override
In light of quieter engines and a quieter interior, the PCM provides
a starter override feature that prevents the starter from operating if
the engine is already running. This avoids embarrassment caused by the
grinding noise and the potential for damage to starter and ring gear.
Starter override is standard with all models and all engines. This
unique feature, for which a patent is sought by Chrysler, is
accomplished through computer logic alone - no hardware is added.

Idle-Speed Control
The PCM (Powertrain Control Module) determines idle speed on all
engines. It actuates a stepper motor and valve in the throttle body to
change idle air flow. This valve is also used to fine-tune air flow to
avoid engine surge when the air conditioning system compressor cycles on
and off.
On V-6 engines, a Dual Idle Speed system minimizes idle fuel
consumption. These engines idle at 625 rpm in Drive when lightly
loaded, that is when the air conditioner or electric rear window
defroster are off. This reduces idle fuel consumption by 10%,
increasing (Environmental Protection Agency) combined city and highway
driving economy by about 2%. Dual Idle Speed software in the PCM
monitors engine operation and increases idle speed automatically to 680
rpm if necessary to provide sufficient power to meet air conditioning
and electrical system needs. The electrical load compensation feature
assures that all electrical requirements are met without draining the
battery or resorting to a more powerful, heavier alternator. The idle
speed is increased to 680 rpm if air conditioning is on (compressor
button pressed) or if electrical system voltage falls below 13 volts.
It returns idle speed to the lower value when battery voltage returns to
normal.

Air Conditioning Compressor Control
To enhance vehicle performance when the air conditioning is on, the
PCM stops the compressor during wide-open throttle acceleration
commencing below a vehicle speed of 20 mph (32 km/hr).

Charging and Cranking Systems
To provide long battery life, starting capability at -20*F (-30*C),
and protection against excessive discharge during storage, the standard
battery with all V-6 engines is rated at 500 CCA (cold cranking amps).
With the 2.4-liter 4-cylinder engine, a 600 CCA battery is required.
Both are maintenance free and protected from life-shortening engine-
compartment heat by a molded plastic Thermoguard. With the optional
heavy-duty trailer towing package, which places added demands on the
electrical system, the battery is rated at 685 CCA. The battery tray is
made of strong, corrosion-resistant structural composite material.
A 1.6 hp (1.2 kW) reduction-gear starter is used with all engines.
A lightweight, compact 90 ampere generator is standard with all
engines. It is driven at 2.9 times engine speed to minimize weight while
producing the required output. A 120 ampere generator is included with
optional heavy-duty trailer towing package, rear air conditioning or fog
lights.

Chassis

Suspension
General Information
Based on customer inputs, the suspension system features a good ride
with low harshness and noise. It also provides outstanding stability on
two-lane highways. Ride and handling qualities begin with a rigid body
structure which allows the suspension to work without being affected by
body deflections. Ride and handling are refined to complement the
characteristics of the structure through attention to detail in the
calibration of suspension, steering and tires.
See also Body Structure in the Body Exterior section.

Standard Front-Wheel Drive Suspension
The standard suspension is designed to provide ride and handling
characteristics suitable for all load and driving conditions. Front
suspension is by rubber-isolated MacPherson struts. It is similar in
concept to that on previous models with added features to improve
isolation and revised geometry. The upper strut mount is larger to
provide increased vertical travel and increased fore-and-aft compliance
to reduce harshness. A patent was granted for the increased vertical
travel feature of the strut mount. The standard 1 inch (25 mm)
stabilizer bar is connected to the struts through spherical-jointed
links that minimize friction and harshness. Toe and camber
specifications were fine tuned during development to provide excellent
directional stability over bumps. Ductile nodular cast iron lower
control arms have in line rubber isolation bushings to minimize
friction. Arm design is asymmetrical, having one bushing opposite the
lower ball joint to resist lateral load and the other rearward to
cushion impact bumps. Urethane jounce bumpers enhance ride when fully
loaded or when negotiating bumps that require full suspension travel.
A rubber-isolated cast-aluminum front suspension cross member is
the largest major structural member of cast aluminum in a US production
vehicle. It weighs about 20 pounds (9 kg) less than a similar design in
steel. The isolators are tuned in three axes to control vibration and
damp out harshness and noise before it reaches the passenger
compartment. The casting has a hat-shaped cross section to which a
steel base plate is bolted.
The cross member has the natural corrosion protection of aluminum.
The base plate is isolated from the aluminum and protected against
corrosion by galvanizing and a thick layer of electro-coat paint.
Corrosion-resistant fasteners attach the base plate to the casting.
On front-wheel drive models, the rear suspension has high strength-
to-weight tapered, single leaf springs and a tubular beam axle with
track bar. Rubber biscuits isolate the springs from the axle. The track
bar increases lateral stiffness to provide a steady ride in the rear
seating positions. The short - 27.5 inch (700 mm) - track bar
supplements the lateral stiffness of the rubber-isolated leaf springs.
Front and rear track are both wider than on prior models,
contributing to handling stability. Front track is 63 inches (1600 mm)
- 3 inches (78 mm) wider; rear track is 64 inches (1626 mm) - 2 inches
(50 mm) wider.

Heavy Load/Firm Ride Suspension
A Heavy Load/Firm Ride Suspension is available for front-wheel drive
customers who consistently carry heavy loads and/or those who desire a
firmer ride than the standard suspension. This suspension has 15%
higher front spring rates and 18% higher rear spring rates than the
standard suspension. Front strut damping on long wheelbase models and
rear shock absorber damping on both wheelbases is also increased for
ride control. The rear suspension also includes urethane jounce bumpers
to enhance ride quality when fully loaded or when encountering bumps
that require full travel to absorb.
Sport Handling Package
A Sport Handling Package is available on front wheel drive models.
It includes the same springs, struts and jounce bumpers as the Heavy
Load/Firm Ride Suspension. The rear suspension also includes a 0.75
inch (19 mm) link-type stabilizer bar to improve handling. 215/65R16
Michelin MX4 "touring" tires and cast aluminum wheels are also included.
See also Tires and Wheels elsewhere in this section.
Load-Leveling Suspension
Load-Leveling Suspension - self-leveling rear suspension shock
absorbers - is standard on all-wheel drive models and optional on front-
wheel drive models in premium or luxury equipment levels. Load-Leveling
Suspension is available with or without Heavy Load/Firm Ride Suspension.
Lower rate springs work with the self leveling shock absorbers to
provide the same rate as vehicles without this feature to assure a
smooth fully-loaded ride and a "normal" attitude. Vehicle appearance is
also enhanced when fully loaded. The new minivans are the first US-
built vehicles to use this system. When passengers or cargo are added,
these units use normal ride motions that occur during driving, even on
very smooth roads, to raise the rear of the vehicle within 0.8-1.0 inch
(20-25 mm) of curb height. When the load is removed, the vehicle
returns immediately to its unloaded height. Operation of the system is
noiseless, simple, highly reliable and requires no driver attention.
The Load Leveling Suspension units are self-contained. There are no
external sensors, plumbing or wiring. Load Leveling Suspension will be
introduced as a running change.

All-Wheel Drive SuspensionAll-Wheel Drive front suspension is the
same as the Heavy Load/Firm Ride front suspension. Design features
affected by this commonization include the tall front cross member that
provides for a high-mounted steering rack to clear the rear drive shaft
and raised steering arm location on the steering knuckle. The steering
rack and steering arms are 2 inches (50 mm) higher than on the previous
front-wheel drive minivan. A unique combination of rear suspension
components are used with all-wheel drive, including non-isolated multi-
leaf rear springs, a unique shock absorber calibration and Load-Leveling
Suspension. Increased lateral stiffness of the multi-leaf springs makes
a track bar unnecessary. There are no suspension options with all-wheel
drive. All-Wheel Drive will be introduced as a running change.

Steering
A precision, ground-edge valve is used in the rack and pinion
steering gear to minimize steering valve hydraulic noise during parking
and low-speed maneuvering. The valve also helps give the steering a
crisp on-center feel. Steering effort is fine-tuned to balance steering
characteristics with vehicle response characteristics. Wider front
track allows a sharper turning angle resulting in a 3.4 foot (1.04 m)
reduction in long-wheelbase turning circle and 3.0 ft. (0.92 m) in short-
wheelbase turning circle compared to 1995 models. Long-wheelbase models
now turn in less space than previous short-wheelbase models and new
short-wheelbase models are even more maneuverable.

Tires and Wheels
Tires are larger and wheels are wider than those on 1995 minivans at
all equipment levels to improve appearance and handling. The larger
tires are consistent with market demand and contribute to car-like
appearance. Standard tires with base equipment level are size
P205/75R14 mounted on 6.0-inch rims. Most other models ride on newly
available P215/65R15 tires with 6.5-inch rims. New 215/65R16 touring
tires on 6.5-inch rims are available exclusively on Chrysler vehicles in
the minivan market. They are standard on Chrysler Town & Country with
LX and LXi equipment levels and are included in the Sport Handling
Package. Touring tires have construction, tread design and rubber
compounding features that favor handling over ride. Tire construction
and tread pattern detail refinements for all tires reduce road noise in
keeping with customer requirements.

Spare Tire and Jack
A full-size spare tire is standard on Town & Country LXi and
optional on all other models, which have a compact spare tire as
standard equipment. The spare tire is stowed under the cargo floor in
both front-wheel drive and all-wheel drive configurations. Under-floor
tire stowage is new for all-wheel drive models. A winch operated by the
tire lug wrench raises and lowers the tire. The compact scissors-type
jack and tire changing tools are stowed in a compartment in the left
rear corner of the vehicle for easy access. Brackets to hold the jack
are welded to the body structure. The compartment has a latching cover
identified by a printed jack symbol. A jacking instruction label is on
the back of the cover.

Brakes

Four-Wheel Anti-Lock Brakes
Four-wheel anti-lock brakes (ABS) are standard on all models and
equipment levels. The hydraulic unit is further simplified from
previous units but provides the same performance and pedal feedback
characteristics. Wheel sensors are the same and electronic controls are
similar to those used in 1995. To reduce ABS operating noise
transmission to the passenger compartment and thereby provide a
perception of smoother operation, the hydraulic unit with its motor,
pump, solenoids and valves is rubber-isolated from its lightweight cast
magnesium bracket which in turn is attached to the rubber-isolated front
suspension cross member.
The magnesium bracket has a corrosion resistant coating for long
life in the hostile underhood environment.

Front Brakes
Disc brakes with sliding, single piston calipers are standard on all
models. Models with 15 or 16-inch wheels have 11.1 x 0.95-inch (281 x
24-mm) rotors; models with 14-inch wheels have 10.2 x 0.95-inch (258 x
24-mm) rotor. All rotors are made from damped cast iron for quiet
operation and vented for heat dissipation. Caliper size is common to
both applications, only the mounting location changes. Calipers slide
on machined guides that are integral with the steering knuckles for
light weight.
Rear Brakes
Rear drum brakes have dual-mode actuation that provides both smooth,
consistent dynamic operation and a parking brake with powerful static
holding ability. Under dynamic conditions, leading and trailing shoe
actuation provides smooth consistent operation. The patented parking
brake linkage provides added engagement action similar to that of a duo-
servo brake to hold the vehicle on a grade with very low pedal travel
and low effort. The cast iron drums are larger o 9.8 x 2.17-inches (250
x 55-mm) o than on prior models with transverse fins and flared inboard
flanges to increase their heat capacity. The mechanisms are self
adjusting.
See also Parking Brake, below.

Brake System Actuation
A "zero lost travel" power brake booster increases customer
confidence in the brake system by minimizing the amount of pedal travel
required to achieve brake actuation. This feature had its first
Chrysler use in the Dodge Viper sports car.
The brake pedal height relative to the accelerator pedal - 2.3
inches (58 mm) - is ergonomically correct for easy transition without
allowing the accelerator to be pressed during braking. The pedal pivots
on a lightweight magnesium bracket.
A conventional tandem master cylinder is recessed in the face of the
booster to reduce its underhood space requirement. The master cylinder
has one fluid reservoir for both front and rear brakes. A neck on the
reservoir makes the yellow filler cap readily accessible. The reservoir
includes a sensor that warns the driver if fluid level is low by means
of a light in the instrument panel information center. The hydraulic
system is split diagonally to provide stopping ability in the unlikely
event that one of the two hydraulic systems loses pressure.

Parking Brake
The parking brake is pedal actuated as in the past, but the pedal is
repositioned outboard and forward of the location on prior models to
provide more driver foot space for ingress/egress and more room for the
driver's left foot when driving. Forward mounting of the pedal is made
possible by new parking brake linkage in the rear brakes, and by design
of the pedal linkage which reduces pedal travel by 50% yet requires less
effort than the 1995 system. A ratchet and pawl mechanism keeps the
brake on; a pull handle on the instrument panel releases the brake.
Contributing to low pedal travel and pedal height, is a separate ratchet
and pawl operated by a torsion spring that automatically adjusts the
cable by removing slack each time the brake is released. The new
parking brake linkage also allows the use of lighter, less costly
cables.

Fuel Supply
The fuel supply system uses the same 20 gallon (76 L) molded plastic
tank for both FWD and AWD applications - an increase of 2 gallons (7.5
L) for the AWD model. The tank is mounted in essentially the same
location as on the previous AWD model - under the cargo floor toward
the left side of the vehicle. The filler cap is located forward of the
left rear wheel A one-piece molded plastic door with integral hinge
covers the tethered filler cap. The hinge has a detent to hold the door
open while refueling. A fueling interlock is included with the optional
second sliding door. It prevents the sliding door from opening when the
fuel door is open. Fuel is delivered from the filler neck to the tank
through a hose that is clamped to connecting nipples at each end.
See also Sliding Doors under Door
Systems in the Body Systems section.
In keeping with current corporate practice, the fuel supply system
is returnless, reducing the amount of fuel vapor that the evaporative
emission control system is required to handle. A five-function fuel
pump module is installed in the tank. This module includes the electric
pump, fuel pressure regulator, fuel reservoir, fuel level sensor for the
fuel gauge and a filter "sock". A large capacity main fuel filter is
mounted forward of the tank has a conductive plastic housing for long
life. It is designed to last the life of the vehicle.

Cooling System
General Information
The standard cross-flow radiator core has a mechanically assembled
tube and fin aluminum core with mechanically attached plastic end tanks.
This results in a very lightweight cooling module that is resistant to
corrosion. A transmission oil cooler is mounted in the left end tank.
With heavy-duty trailer towing package, the radiator has brass tubes and
copper fins for added cooling capacity. This radiator also includes a
higher-capacity in-tank transmission oil cooler.
Two fans are used to provide full coverage of the low, wide radiator
and air conditioning condenser. The motors are lighter and less costly
than previous two-speed units which required additional wiring to
provide the second speed. Motor speed is controlled by the PCM
(Powertrain Control Module). A molded plastic fan shroud guides
incoming air through the full face of the radiator. All system
variations includes a conventional remote-mounted recovery bottle. An
air dam below the front fascia helps direct cooling air into the
radiator.
The coolant pressure cap is located on the radiator. The thermostat
is vented so that trapped air can escape when the engine is not running.
This makes refilling easier than with an unvented thermostat. All
coolant hoses are peroxide-cured for longer life.

Variable Speed Fans
Cooling system fan speed is continuously variable so that fan speed
is no higher than required to maintain proper cooling, minimizing fan
noise. The lowest operating speed is lower than that provided by
previous two-speed fan systems. To vary the speed, electrical power is
supplied in pulses of varying width which is modulated by the PCM. In
addition, fan speed at startup is increased gradually for a more
esthetically pleasing sound.

Exhaust System
With all engines, the exhaust pipe and manifold are flanged and
sealed with a gasket for quieter operation than the spherical "doughnut"
used on previous models. A bellows-type flexible coupling in the exhaust
pipe allows relative motion between the engine and the pipe. This
connecting system provides life-of-the-vehicle durability.
The exhaust system uses stainless steel for all pipes, the catalytic
converter housing, muffler and resonator in common with other corporate
vehicles. Extensive development and tuning of the systems along with
tighter control of production tolerances has produced quieter, more
pleasant sounds with approximately 15% less back pressure than prior
systems. Exhaust system mounting follows the concept used on prior
models.


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