Engine/Transmission (1994 - 1998) PCM Question

[CToney]

Will a PCM off of a '95 5sp work on a '97 5sp. My pcm seems to be giving me grief charging my alternator. Sometimes it charges up right away other times I have to drive a long ways. New batteries, recent bearings and brushes in alternator, tach and cruise works, good batt connections. I think my pcm may have gotten wet with the holes in my cowl. I have access to a '95 pcm so I hope it will work?



Thanks

CR Toney

 

[JoeBioDiesel]

Before I switched the PCM I would just wire the alternator to an old style regulator. It will work just fine that way. But, before I did that I'd have it checked by someone with a scanner. See what the desired charge voltage is. Maybe it is not charging the battery because of a failed input, like a crank sensor, battery temp sensor, something like that.



Joe

 

[Howard Durand]

If I am not mistaken, the 95 has a single module PCM where the 97 has three. Before changing it I would pull the plug on the existing one first and douse the connectors and connections with a good electronic cleaner. Also check the wiring for damage or bad connections. Any water that has gotten to the PCM should only affect the connectors. I doubt if any can actually get into the PCM itself. If you can't find anything try Joe's remedy.

 

[SCosgriff]

95 is a single plug connection and the 97 has 3 plug connections. Also they are running two different transmissions 47RH verses 47RE. 95 PCM probably doesn't have enough electronics to control the electronic trans properly.

 

[Lightman]

95 is a single plug connection and the 97 has 3 plug connections. Also they are running two different transmissions 47RH verses 47RE. 95 PCM probably doesn't have enough electronics to control the electronic trans properly.

In his case they arent running 2 different transmissions 5 speed vs. 5speed same transmission. That being said a 1995 computer will not work because of the above mentioned wiring connections and other wiring differences, the 95 is not obd 2 compliant and the 97 is. A 96 would plug in to a 97 but would not charge correctly. A 97 would plug into a 1996 and charge correctly. A 98 12 valve will not work in anything but a 1998. I have spent many hours studying wiring diagrams and inner changing computers between 1996-1998. You can make some very minor wiring changes to make a 1996 work in a 1997 though.

 

[Ahopper]

not trying to steal the thread but i had a few questions also. my governer pressure siliniod keepes going out in my trannie. i called dtt and they said it is the PCM buring it up does anybody have any experiance with this. it seems gradual. the last couple of days i have been having to let off the throttle for it to shift ito second or third. and also from the last thread i take it that if you have a 97 the easiest way to replace one is to find another 97 to put it in?

 

[tlgdiesel]

Your best bet is just to replace it with the same year computer, you are correct in that statement.

 

[Dave M]

I have a PCM from the dealer for my 97 5spd that I bought for about $600 but it turned out to be the Engine Speed Senser (Crank Position Senser).



Here is the thread I posted:



https://www.turbodieselregister.com...ons/184945-electrical-woes-maybe-bad-pcm.html



I used it for 5 minutes and figured out it was the crank senser. The crank Senser cost about $100 so now I'm out $600+ for a PCM I don't need. I still have the original box and install instructions that came with it. If you are interested in buying it let me know.



Dave