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Maintenance

Discussion in 'Dakota, 1998-2013 Durango and Aspen' started by Scrounge, Jan 21, 2016.

  1. Scrounge

    Scrounge Well-Known Member

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    After repairing a vacuum leak, my '92 Dakota V6 had consistently been returning about 21 freeway mpg. But when I drove it to Michigan last month, it's mileage was 19 mpg at best. I changed the spark plugs in Texas last week, replacing Bosh Platinums with Champion RC12YC Copper Plus plugs, but while performance improved, gas mileage didn't. I also replaced the driver's side valve cover gasket because the mechanic who replaced the rear freeze plug said it was leaking oil. The old gasket wasn't cracked anywhere, but gasket glue had accumulated around the bolt hole near the #5 plug. Maybe the oil stopped leaking, but it's still losing a quart about every 1500 miles. Time to replace the PCV valve again? The cruise control had been going flaky, occasionally cutting out and even not setting, but after the plug and gasket replacements, only resume won't work, which seems to be a switch problem. I squirted electrical spray cleaner into it, but no improvement.

    A glitch developed: when the speedometer is on 70 and showing 2200 rpm, the truck is actually going about 67 mph. However, driving through Arkansas, I noticed that the tach read 2400 rpm at 70 mph. A quick calculation (48 seconds between mile markers divided into 3600 seconds in an hour) determined that 70 was actually 75. This returned to its normal reading of 67 for 70 after I stopped for gas, but rose again after another stop. Don't know what this problem is, but I'm leaning toward greasing the speedometer cable, even though it's not making any noise.

    Another glitch seems to be related to very cold weather, as it's only occurred in Michigan. The shift point from 1st to 2nd gear is usually around 15 mph or less, but here, it occasionally goes to 20 mph, and well above 2000 rpm, before shifting. A mechanic said that this could happen if the fluid in the torque converter isn't warm enough. I'd like to change the trans fluid and filter soon, as it's now over 45K miles since the last change. The cheapest ATF+4 I've seen is around $4.25/quart at Wal-Mart. Do any retailers sell ATF+4 in gallon jugs for less than $17? Also, how can I tell exactly what transmission I have? From what I've read, 3 separate automatics were available with the Dakota V6 in the early '90s.

    On the way back home 2 weeks ago, the headlights cut out twice at night, though they came back on soon afterward. I replaced the headlight switch with one from a junkyard, and so far, that problem hasn't recurred.

    Yesterday, I cleaned the crankcase breather. According to the shop manual, it should first be soaked in kerosene, but I didn't have any, so I used gas. It didn't say how long the soaking should last, so I left it for about an hour. After that, it said to fill the breather from the bottom side with straight 30W, then tip it to let it flow out, but again, I had to use a substitute, 10W-30. The breather didn't seem very dirty. I also added a small can of fuel injector cleaner yesterday. Too early to tell if that will improve gas mileage.
     
  2. valiant67

    valiant67 Rich Corinthian Leather
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    Was it a Mopar PCV valve? I've had others increase oil use in my Dakota.
    I'm not sure you have a speedometer cable. it may be electronic from a speed sensor.
    In 1992, there shoudl have only been two automatics, the A500 (42RH) and A518 (46RH). The mid-level transmission (44RE) didn't come until later. The way to ID is by the shape of the transmission pan. A500 pan is shaped like a 904 pan, A5018 pan is shaped liek a 727 pan. Most aftermarket kits include both gaskets and the filter is the same.
     
  3. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    OK, so:

    Gas mileage variation from 21 to 19 is nothing unusual. Changes in temperature, traffic, slopes that you are climbing, all affect gas mileage enough to account for this. Tire pressure as well.
    I found, like others, that my oil consumption in my Daytona was cut in half just by changing from aftermarket to MoPar brand. Since my Dakota used to go 8,000 miles a quart and now only goes 2,000, I'm going to go OEM on my truck's PCV valve, also.
    Tach - these tach drive boards are garbage and often fluctuate in reading. I've found mine reading over 2000 when I know it should be 1800 at 65 mph. I've dug into the circuit design on this board, and it runs hot. So don't worry about it. And the speedo generally reads about 2 mph higher than actual, on my truck. This is normal error. There is no speedometer cable, as I recall. It's all electronic.
    My transmission often shifts a few mph late in really cold weather. Sounds like yours is normal, and I would not service it just for this reason.
    You have the A500 (42RH) transmission with the V-6 engine. It's a combination of A904 and A727 parts, with an electric overdrive unit bolted to the back for 4th gear.
    If the breather was not really, really clogged, it will make no measurable difference in gas mileage. But it's good to do all recommended maintenance.
     
    Scrounge likes this.
  4. Scrounge

    Scrounge Well-Known Member

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    It's a Napa PCV valve. The Mopar dealers closest to me in Texas didn't stock that OEM part. I'll check the one near here, but it will probably be harder to find in Michigan, since vehicles don't last as long here due to rust, which makes parts suppliers ship parts for older vehicles to the south and west.

    I probably should have added that I replaced the air filter about 1 1/2 years ago. While no longer new, it's still relatively clean; a flashlight shines through it all the way around. I've not detected any vacuum leaks, and the truck runs like it doesn't have any.

    Glad you mentioned tire pressure, Bob. I bought new ones over the summer, and had ignored them since then, but when I just checked them, 3 were 5 psi low. I'll fill them after posting this. It may be a few weeks before I know whether and/or how much it affected mileage, but they're certainly a drag when they're low. As for traffic and slopes, it's the same route I normally take. If temperature is a factor, it should be more so up here than during the first half of the trip where the climate is milder. This time, though, there were some stiff crosswinds.

    My tach is reading higher when the speed actually is higher, so it should be ok. Were the speed the same, I'd suspect it. Not only did I calculate a higher speed at 70 during those intervals, radar signs in construction zones indicated that I was going 49 when my speedometer showed 45. Where is the speed sensor located? I've not found it in the FSM: in fact, it states that it has "a cable driven speedometer". It's been a while since I've had the entire cluster off, but I think I had to disconnect a cable from the speedometer to completely remove it. I may have greased it then, but again, I don't remember. If it has a sensor, I'd like to find one in a junkyard and see if it helps. I don't have a problem with it reading 2 or 3 mph higher than actual speed, but when it reads lower, no speed cop will accept that as an excuse.

    Thanks for telling me what transmission it has. According to the FSM, the automatic transmission drain & refill interval should be 37,500 miles for a light duty cycle under normal usage. This is the longest interval recommended, and tells me that I'm overdue. Also according to the FSM, the fuel filter should be replaced "as necessary". According to the previous owner's cousin (who performed the truck's maintenance), it was replaced within the year before I bought it, but that would also make it more than 45,000 miles ago. And it recommends that the oxygen sensor be replaced at 82,500 miles. I don't know if it ever was, but even so, it's due for another one.
     
  5. Scrounge

    Scrounge Well-Known Member

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    The local Dodge dealer wanted more than $12 for a PCV valve, and it wouldn't arrive for more than a week. I instead bought an Echlin valve at Napa for $4.29 plus tax. This time, they actually charged the online price in the store.

    All of the tires were down, so I aired them up to 32 psi. It'll be a week or so before I head back to Texas, when I'll check freeway gas mileage again.
     
  6. Scrounge

    Scrounge Well-Known Member

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    Back in Texas. Only 2 freeway mileage readings, the first was 19.0 mpg with lots of stops, the next was 20.4 mpg, about half freeway and half through smaller towns about 15 to 30 miles apart. Correct tire pressure probably helped, but after filling up in Arkansas, the speedometer consistently read 3 mph faster than actual speed. It occasionally read 4 mph slower until then. It's possible that when I don't catch it in time, the faster speeds will use more fuel. I read a bit more about the speedometer in the FSM. It shows a "distance sensor" between the cable and the transmission. It describes how to replace it, but under diagnosing, it states, "For testing of the distance sensor and related components refer to the Vehicle Diagnostics Test Procedure Manual." Aggravating. If it's the problem, does it always have to be replaced, or might it operate properly after a good cleaning, and if so, with what kind of cleaner?

    After arriving home, the oil level was a quart low. This covered a bit more than 1300 miles. The new Napa PCV valve made little, if any, difference. Time to scrounge around for the OEM part.

    The cruise control resume function doesn't work on either the junkyard unit or the original switch, though set works fine on both. It's possible that both switches are bad, but might the servo be the culprit? Or something else?
     
  7. AllanC

    AllanC Well-Known Member

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    Since your cruise control will operate and hold a speed when the SET button is depressed, the distance sensor is functioning properly. If the distance sensor was not sending a proper signal to the PCM (powertrain control module) the cruise control would not engage and hold a steady speed. So you do not need to do any further testing on the distance sensor.

    The speedometer is a mechanical unit, not electrically driven so the distance sensor has no effect on the speedometer. So if the speedometer needle varies I would suggest you remove the speedometer cable from its sheath and lubricate it with engine oil and then reinstall.

    You indicate that you can press the SET button and the cruise control will hold the desired speed? But after traveling with the cruise control engaged, you press the brake pedal, the cruise control disengages, the vehicle slows but will not resume the previous set speed when the RESUME button is depressed?

    If this is the situation try this test. On the open road set a speed such as 45 mph. After traveling a short distance press the brake pedal to temporarily release the cruise control and allow the vehicle to slow to 40 mph. Then press the accelerator and bring the vehicle back to 45 mph. With the vehicle moving at 45 mph (your previously set speed) press the RESUME button. If the cruise control will now hold the speed, the problem is with the cruise servo. The internal solenoid controlled valves that pulse and vary vacuum to the unit are leaking. If it will not resume and hold the 45 mph speed, you will have to check the wiring and make sure there is battery voltage on the resume control wire that originates at the resume switch and travels to the PCM.

    Section 8 of the FSM should have a subsection that details wiring diagrams and a test procedure for the cruise control. Look at the table of contest on page 8A -1 and it should be listed.
     
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  8. NYBo

    Level III Supporter

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    Are the cruise control switches on the steering wheel? Bad clockspring.
     
  9. Scrounge

    Scrounge Well-Known Member

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    NyBo: yes, they're on the steering wheel, to either side of the horn. My understanding is that this type of switch was only used during the '92 and '93 model years, I think across all models.

    Allan: Thanks for eliminating the distance sensor. I'd previously used grease on the speedometer cable, but if motor oil will work, I'll use that. Right, SET engages whenever I hit it, but RESUME doesn't. I'd not previously tried to resume at exactly the same speed; I'll check that tomorrow, when I head out of town.
     
  10. Scrounge

    Scrounge Well-Known Member

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    I tried RESUME at the same speed as SET several times over about 25 miles, and it never worked. It's possible that both switches are bad, since resume is used more often than the others, but the clockspring could be the culprit, or anything electrical in that circuit. I'll check the FSM when I return home. I also started what became a long thread on this topic about a year or so ago; I'll look that up, too.
     
  11. ImperialCrown

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    Speed control electrical tests are covered in chapter 8H. You don't need a scan tool, just a volt-ohmmeter should do.
    Test the switch resistances through the clockspring further down the column if you suspect that the clockspring might be open.
    Remember that the brake pedal switch is 3 switches-in-one and just because the rear brake lights work OK doesn't mean that the rest of the switch is good or adjusted correctly.
    I have had some speed controls start working by lifting up on the brake pedal with my toe.
     
  12. AllanC

    AllanC Well-Known Member

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    On the 1992 Dakota the cruise control switches were NOT multiplexed such that as each steering wheel switch is operated, a unique voltage is passed through to the PCM. On this model operating a cruise switch results in full battery voltage appearing on the various cruise wiring circuits.

    I looked at the diagram for a 1991 Dakota and it very well might be different for a 1992 - 93 model. There are 4 wires that go through the clockspring wiring mechanism for the cruise switches. A red / light blue tracer provides fused, switched power to the switches. A yellow / red tracer indicates ON / OFF to the cruise circuitry at the PCM. A brown / red tracer wire has momentary battery voltage when the SET button is depressed. A white / light green tracer wire has momentary battery voltage when the RESUME / ACCEL button is depressed.

    Since the SET function of the cruise control functions properly, you know that the brake sense switch on the pedal is operating properly. If this brake switch were misadjusted or broken then the cruise SET function would not work and hold the desired speed.
     
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  13. Scrounge

    Scrounge Well-Known Member

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    IC and Allan, thanks for the additional info. I didn't have time to look last night, and am on my way back to Michigan after posting this. I'm bringing the FSM, so I'll check it there the first chance I get. Allan, is your switch underneath the horn? Other than the switch, the wiring diagram might be similar, though we'd have to compare manuals to see. The key dance only returned code 55 (end of sequence). I think 15 would have indicated a problem with the distance sensor.
     
  14. AllanC

    AllanC Well-Known Member

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    The steering wheel between a 1991 and 1992 Dakota is different. On the 1991 model, the cruise control switches (ON / OFF, SET, RESUME / ACCEL) are at the bottom horizontal spoke of the wheel. If you have the service manual, look in section 8H and you should find a troubleshooting section that details how to check the switches. Section 8W will have the wiring diagram and compare with what I have outlined in a previous post.

    You are correct. If there was a problem with the distance sensor, diagnostic code 15 would be present.
     
  15. Scrounge

    Scrounge Well-Known Member

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    I tried one additional test en route: the RESUME switch won't accelerate, either. It doesn't affect the speed when the cruise control is set.

    Looking at the FSM, the cruise control wiring diagram is AN 23 and AN 24. The wiring is the same as the '91, except that the fused switched power wire is white/red on mine. On the switch side of the clock spring, that wire shows DB/WT (dark blue or dark brown?), and the RESUME wire is only white. The others are the same.

    At the moment, it's 15 degrees and windy outside. I'll start electric tests when it warms up to at least above freezing here.
     
  16. AllanC

    AllanC Well-Known Member

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    Since the cruise control operates and will hold a set speed, your troublehooting of the cruise control is simplified. I would suggest you look at the connector pinout for the electrical connector at the PCM. Find the receptacle cavity that is the RESUME wire (white as you indicated) at the PCM connector. Back probe the connector by inserting a metal paper clip or T pin in the connector. You can use this back probe to test if battery voltage appears on this RESUME wire at the PCM when the resume steering wheel switch is depressed with ignition in the RUN position.
     
  17. Scrounge

    Scrounge Well-Known Member

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    Thanks, Allan, I'll run that test first.

    Keep forgetting to mention, I also replaced the positive battery terminal last month. I replaced the original one last year, but it corroded early and often. I found one of those felt pads in the garage, and put it on first. So far, no corrosion.
     
  18. Scrounge

    Scrounge Well-Known Member

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    The weather finally warmed up enough so that I could wash the salt off the truck and change its transmission fluid. Five quarts wasn't enough, but six was too much. It's about 1/8" above the full line.

    According to the shop manual, Page 8H-6, there are 2 tests for Resume. Step 6 reads, "Touch the positive lead of the voltmeter to the terminal in cavity number 50. The voltmeter should read 0 volts with the speed control switch in either the OFF or ON position. With switch in either RESUME or SET position, the voltmeter should read battery voltage." Step 7 reads, "Touch the positive lead of the voltmeter to the terminal in cavity number 49. The voltmeter should read 0 volts with the switch in the OFF position. With the switch in the ON position the voltmeter should read battery voltage. The voltmeter will continue to read battery voltage when either the SET or RESUME switch is pressed." Well, it reads battery voltage whenever the RESUME switch is pressed in both cavities. In Step 6, however, it reads battery voltage with the speed control switch on. Also, when I bolted the connector back in and tightened it, the bolt hole in the PCM came out of its slot. Might this have caused a loose connection? I put it back in, and screwed the bolt snug, but not torqued. I'll epoxy it when I return home. I've yet to test the RESUME switch with the cruise on, and might not do so for a few days -- it's difficult to find a freeway with light traffic around here.

    It used a quart of oil in about 1500 miles. When the engine is on, there's sort of a buzzing sound coming from the PCV valve. Is this normal?
     
  19. AllanC

    AllanC Well-Known Member

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    Go to wiring diagram AN 21 and AN 22 to follow my description. There is 1 input circuit and 3 output circuits on the cruise control switch. The input circuit connects ignition switched fused battery power to the cruise control switch. Ignition switch must be in ON / RUN position and fuse must be good for any of these tests to be valid.

    Cavity 49 at the PCM is the ON / OFF sense from the cruise switch. When the ON / OFF button is depressed and stays down, battery voltage will appear at cavity 49. The SET switch connected to cavity 48 is normally closed until pushed. So with the ON / OFF button depressed and cruise system activated / turned on, cavity 48 will have power. If you depress the SET button battery voltage is interrupted at cavity 48. The SET function works properly so further checking is not needed on that circuit. Since there is power at the cavity 49 and 50 you know the ON / OFF switch is functioning properly.


    Cavity 50 at the PCM is the RESUME / ACCEL sense from the cruise switch.It is normally open. Cavity 50 will have battery voltage when the RESUME button is depressed and will revert to 0 volts when the RESUME button is released. The service manual description can be misleading but you have proven that the 3 outputs from the switch are functioning properly and there is no problem with the cruise control switch.


    I believe you mean the threaded receptacle that mates with the attaching bolt has loosened in the body of the PCM. Most definitely a loose connection can cause this issue. Secure it as you have outlined and test the RESUME feature.

    My 1991 Dakota with 5.2 V8 has an oil consumption of about 1 quart per 1500 miles. I owned a Dodge Dart from 1973 - 77 with the 5.2 / 318 V8 and its oil consumption was about the same. I am thinking the V6 is the same V8 design with pistons and rings. The V8 dates from the 1960s. Engines from these older designs did not have modern day close tolerances and some oil consumption should be expected. Maybe others with these engines will comment about typical oil consumption.
     
    #19 AllanC, Feb 29, 2016
    Last edited: Feb 29, 2016
  20. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    My 3.9 V-6 Dakota was going up to 8000 miles a quart when I bought it from my brother in 2004. Lately it has gone down to about 2500 miles per quart. Might be because I experimented with a K&N drop-in filter for 30K miles, or because it's an aftermarket PCV valve. I have a Mopar PCV ready to go in, and it's due for an oil change soon.
     

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