Engine/Transmission (1994 - 1998) No tach, no charging, no a/c, no hair left

[ctfxr3]

Julie,

Glad I stumbled upon your post, as yours is the first in which I have seen my exact same symptoms. I have only experienced the issue once as I just purchased it two weeks ago, however I was made well aware of the issue by the previous owner. He had replaced the CPS(ESS) as well as the alternator with no positive result. There are a few minor differences but my issues occur as follows:

1) Check engine light will flash and then die out
2) At the same time the tach will bounce and then die
3) Cruise control dies
4)Volts drop wayyy off
5) And of course the OD is dead

Like yours this only occurs when it is hot enough, primarily the outside temp not the truck itself. The previous owner spoke to a diesel mechanic who suggested the pcm be replaced, but like Julie I want to pinpoint it to the PCM before shelling out the $$$ for a new one. Anyone have any advice on this?

Also* he said the AC was weak but maybe it is because of whatever issue is going on here? There is also a manual lockup switch in the cab which will lock it into 3rd when this issue occurs.

 

[1workinman]

this may or may not help. When the problems occur REMOVE the pcm place it in the freezer for a length of time to cool of the unit, reinstall the pcm and see if the truck returns to normal functions . If so that would to me indicate the problem is in the pcm

 

[Julie]

I took a weekend and went thru the wiring harness. I did this with a friend who is more anal than I am ( and I am pretty bad.) We could not find anything amiss with the wiring. Put all together, drove truck, same issues. Talked with 2 shops that do only electrical problems and both felt it was pointing to the PCM. Called two places that remanufactur the units. I did not have a good feeling about either. Went down to the Dodge dealer and ordered a unit. After telling me I could not have the part number in my truck that was in my truck per my vin, they said they would have to order a diff unit(newer). Could not be sure I would get my core $. When I took the unit in they told me I would get a diff unit (older). When the unit showed up it was my part number. Go figure. Right hand, left hand and nothing in the middle. They told me I would need to have the unit flashed...... I put the unit in and so far all as been fine.

I waited to post my results because without the same amount of heat as before I was not comfortable with my testing of the newer PCM. I put my camper on and waited for a warm day, 80, and could not get any issues to appear. I guess I won't feel really good until next summer. Thank you all for your help. Just for reference, the bill from Dodge was $650.00. $125 more if my core was not acceptable. I find the last part interesting. The PCM is no good....why is the part number such a big deal. That unit was the original PCM even though Dodge said it did not match my VIN #.

 

[1workinman]

Julie I bought the pcm from a Dodge dealer in Florida , found the on line discount number on the net. I believe the price was around 380 plus core. There is so tired of the bs happing on my truck that the price did not bother me after a few weekends of the drama . The part number on the pcm is on the net also along with the reflash . I was told that the tools to do so is probably not at the dealer anymore long since gone . My friend in Dallas told me to avoid the aftermarket rebuilt pcm and he told me what he paid for it unit from dodge . The 650 is a price that was quoted from on dealer also. I thought if I had taken the truck to a dealer to fix they would have charged me list price and parts changed until the got it fixed. Not a pretty picture and when I got the bill I would have been told its an old truck. Glad you got it fixed Jim

 

[Missouri Mule]

Glad you got fixed!

 

[ctfxr3]

Julie,

Do you mind sharing the part number on your replacement ECU/PCM....I dont care what its called at this point, I just want one that works. Thanks

 

[ctfxr3]

New symptoms to add to the bunch now the truck is not holding a charge. Left a phone charger plugged in for a little over a week like a dumba** while it was parked in my garage (fixing rust, painting rockers, etc.) batteries dead. Jumped it ran fine now once the ECM/OD/Whatever issue I have going on kicked in the batteries are dead. Can jump the truck but while running the voltage meter is basically showing that the truck is off, along with tach, OD, cruise, and also had the wait to start flash while driving yesterday. Got to be the ECM ....anyone? Alt has been replaced as well as the ESS and no improvement.

 

[GAmes]

You need to post the year and transmission type of your pickup. Almost every year is different and autos use different PCMs than manuals.

 

[ctfxr3]

I am aware of the differences, good call on posting the info though I forgot to do that. Prob would help you guys be able to point me in the right direction


I have a pcm I am going to try today, it was out of the same truck as mine and put in to fix the same issues. Hopefully this does the trick.

1995 12v auto (47rh)

 

[ctfxr3]

New ECM/PCM (don't care what its called) is in and so far so good. Fingers crossed.