PCM problems

[tmarti96]

I am having problems with my transmission shifting gears, 3rd to 4th. Sometimes just won't shift. I have new TPS, new Crankshaft position sensor, and now my dealer tells me the PCM is faulty. Before when my shifting problems happened, the AC quit and alternator quit charging!! lThese problems are not constant. Sometimes it will run fine for two or three weeks then all hell brakes loose again. Does anyone know where I can get an aftermarket PCM or a rebuilt one? Dealer wants 550. 00 for new one!! Any help is appreciated.

 

[Strick-9]

I had some PCM problems several months ago. Much like you describe, I lost AC and my alternator wouldn't charge. This happened because my crank position sensor wasn't signaling my truck's PCM that it was now running. It turned out to be a weak PCM ground. It was the same ground that is used for the crank position sensor. Thus causing the problem.



I tapped into the ground wire at the PCM and grounded it to the fender where the passenger side battery also grounds. No more problems since.



Question: Does your tach still read properly when the AC quits and the alternator won't charge? I believe mine goes to zero when everything else fails.



If you have a Haynes manual or a service manual for your truck locate the ground wire that also goes to the crank sensor and ground it.



It can't hurt to try.



-Chris

 

[tmarti96]

Chris, thanks for the reply and suggestions. When this problem first surfaced, my tach became quite erratic and sometimes quit along with the AC and alternator. I replced crank position sensor, cleaned all the battery cables, replaced the TSP and the problem went away. Then it reappeared, with the same symptoms except the tach. I works OK. I will try the ground check you outlined. thanks a lot.

 

[Bugman]

When I finally broke down & bought a new PCM, I bought it from Longhorn Dodge, Fort Worth. It was a rebuilt one and cost about $250.



Be very carefull you get the correct one. I was given the wrong one to start with, they back ordered the correct one, and quess what, the original part # wasn't even mentioned anywhere... ... . go figure.



Now it even shifts to overdrive without my manual switch.



Bugman.

 

[tmarti96]

Bugman, How do you know when you have the right PCM? All I can do is give them the serial number of the vehicle and hope they send me the right one, I guess. Longhorn Dodge, Ft. Worth, huh. Maybe I will give them a call. Thanks for the info.

 

[Bugman]

Originally posted by tmarti96

Bugman, How do you know when you have the right PCM? All I can do is give them the serial number of the vehicle and hope they send me the right one, I guess. Longhorn Dodge, Ft. Worth, huh. Maybe I will give them a call. Thanks for the info.

Martin, sorry for the delay in answering, I've been out of town. From what I recall, it went like this:



They back ordered the PCM for my truck and it took about 3 weeks. This PCM matched the one in their computer.



When I got home I went over the instruction book. I found an extensive list of PCM part #'s and applications. The one I was about to install was for a 96, NOT a 1995.



I called the dealer and asked for the part # in the book that probably was written by the rebuilding company. 2 more weeks. .



..... installed the correct one.



Was packing my original PCM to return for the core deposit and noticed that it's part number was different from any of them.



It's part number (will post if I find r'cpt) was 'unknown' to the Dodge parts Database. My truck was built in Mexico I think.



How do you know when you have the right PCM?







I don't really know for sure but mine works just fine.



Bugman.

 

[tmarti96]

rebuilt PCM

Bugman, do you have any contacts or friends at Longhorn Dodge I could talk to? I am from Georgia and yu know how long distance transactions are when you are dealing with a total stranger. thanks.

 

[Bugman]

Longhorn Dodge 1-800-772-2744 and ask for parts, I have the initials as KT on the invoice. He was very helpful. I think his name was Keith.



Part # R6028336... ... ... ... ... ... ... 137. 34 approx

Freight... ... ... ... ... ... ... ... ... ... ... ... ... . 40. 00 "

Tax... ... ... ... ... ... ... ... ... ... ... ... ... ... ..... 12. 00 or so



Bugman.