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Discussion Starter #1
Trouble with power loss light 1987 Lebaron Turbo burns up TPS

A friend is working on my 1987 Lebaron convertible ...39k actual.....finishing up the rebuild/install/tune and the TPS went "poof" ...a puff of smoke......he has worked on the wiring, ecm's...it even went to the electrical repair specialist for 3 weeks......it usually takes the specialist 2 days to find and fix.They have all pretty much given up

So power loss light is on because of the TPS and likely because the ecm(s) need to be repaired?...he has the factory service manuals and neither of them have been able to diagnose the problem.

Most "rebuilt" ecm's are no good (from what I am told) but I hear about a guy in Florida who used to rebuild for Chrysler Corporation and he is "supposed " to be THE guy to diagnose and repair ecm's.

Has anyone here heard of him? or can anyone reccommend someone of that caliber?..beating our heads against the wall with this one

2.2 turbo
new cylinder head
rings, bearings, pretty much if it was any kind of sensor under the hood its been replaced

Its a damn shame, I've had this car for over 2 years and haven't driven it yet.....blue, blue leather inside, white top

Any help would be appreciated///thanks!
 

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The TPS and other sensors run on a reduced 'low current' 5 or 8 volt supply from the ECM (PCM). Any short to ground or a high current draw will put the sensor power supply into protection.
If it actually smoked, then it is either wired wrong or the PCM is faulty and it is getting a full 12 volts. What voltage are you reading at the TPS power supply pin? Are the other sensors reading the correct voltages?


•   Charging system malfunction: Alternator defective or battery not fully 
charged. NOTE: In 1985 and later vehicles, the voltage regulator is
controlled by BOTH the Logic and Power modules. In many vehicles,
the voltage regulator is in the alternator.
•   Verify model year of vehicle electronics: Some 1987 P-bodies with 
turbocharged engines were built with 1986 logic modules. A 1986 logic
module can be identified by the MAP sensor mounted on the logic
module case, unless TSB #18-03-86 has been performed. Then,
the MAP sensor is separate. The 1987 logic modules used MAP 
sensors mounted in the engine compartment.
•   Intermittent grounds: Loose or corroded grounds may cause false 
sensor readings.
•   Loose or corroded pin connections: Water leakage through 
kick panel may cause logic module pins to corrode.
•   Manifold Absolute Pressure (MAP) and Throttle Position Sensor 
(TPS) voltages: Check voltage over the entire range, not just the
extremes. Verify minimum TPS voltage.
•   Auto-shutdown (ASD) relay operation: Verify distributor connections 
and proper voltages. Some aftermarket pickups have not worked
properly with Mopar engine controllers.
•   Automatic idle speed (AIS) motor: Shorted windings will set DTCs. 
Open circuits and intermittent connections will not.
•    Vacuum system: Contaminants or leaks in vacuum lines, notably 
in line connected to MAP sensor.
•    Excessive current on certain connector pins may damage the 
modules. Use of a test lamp or a short in the wiring harness of
the vehicle can cause this condition. Always use a DVM when
checking the unit/system.
•   Check Technical Service Bulletins applicable to model year and 
system malfunction.
 

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I agree, someone wired it wrong when they put it back together. There isn't enough current flowing through a normally-wired TPS to burn it up.
 

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21 Posts
Discussion Starter #4
ImperialCrown said:
The TPS and other sensors run on a reduced 'low current' 5 or 8 volt supply from the ECM (PCM). Any short to ground or a high current draw will put the sensor power supply into protection.
If it actually smoked, then it is either wired wrong or the PCM is faulty and it is getting a full 12 volts. What voltage are you reading at the TPS power supply pin? Are the other sensors reading the correct voltages?


•   Charging system malfunction: Alternator defective or battery not fully 
charged. NOTE: In 1985 and later vehicles, the voltage regulator is
controlled by BOTH the Logic and Power modules. In many vehicles,
the voltage regulator is in the alternator.
•   Verify model year of vehicle electronics: Some 1987 P-bodies with 
turbocharged engines were built with 1986 logic modules. A 1986 logic
module can be identified by the MAP sensor mounted on the logic
module case, unless TSB #18-03-86 has been performed. Then,
the MAP sensor is separate. The 1987 logic modules used MAP 
sensors mounted in the engine compartment.
•   Intermittent grounds: Loose or corroded grounds may cause false 
sensor readings.
•   Loose or corroded pin connections: Water leakage through 
kick panel may cause logic module pins to corrode.
•   Manifold Absolute Pressure (MAP) and Throttle Position Sensor 
(TPS) voltages: Check voltage over the entire range, not just the
extremes. Verify minimum TPS voltage.
•   Auto-shutdown (ASD) relay operation: Verify distributor connections 
and proper voltages. Some aftermarket pickups have not worked
properly with Mopar engine controllers.
•   Automatic idle speed (AIS) motor: Shorted windings will set DTCs. 
Open circuits and intermittent connections will not.
•    Vacuum system: Contaminants or leaks in vacuum lines, notably 
in line connected to MAP sensor.
•    Excessive current on certain connector pins may damage the 
modules. Use of a test lamp or a short in the wiring harness of
the vehicle can cause this condition. Always use a DVM when
checking the unit/system.
•   Check Technical Service Bulletins applicable to model year and 
system malfunction.
Thanks a lot for the info, the car is 800 miles away. Usually I would be working on this myself but since its at a friends shop he said he would do it for me (that was just over 2 years ago). One way or another it will be coming home with me at the end of October...either on a dolly or I will be driving it (preferably) thanks again!
 
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