1stgendodge

Does anyone know where I can buy a pcm for my 1993 w250 Cummins automatic? I think I norowed my overdrive issues down to that. The only place I could find anything about a pcm for that truck was SIA Electronics, which I would have to ship my pcm to, to get tested/repaired leaving me without a drivable truck. The other option I found was to get one out of a salvage yard, but there is no garantee that it will work.

I am either looking for a pcm that is new, or is used and guaranteed to work.

Thanks in advance

oliver foster

I have one or two auto '92/'93 PCMs left from trucks that I drove so I know they work.
PM if you like.

eljefedavies

Have you checked your crank sensor? I was told my PCM was bad and after replacing it I still had the problem, it turned out to be just the crank sensor. Everyone said the crank sensor works or doesn't, well mine was intermittent so it was hard to verify. I finally just replaced it and my problems disappeared. I then did the TPS bypass and had no problems for the past 10 years.

1stgendodge

yes, in my other thread I was having issues with my tps. The truck will only shift into OD when the tps reads 0 volts at idle and WOT. Wiring looks ok, which leads me to believe the pcm is bad

j_martin

Take his advice and check the CPS. I believe it is a hall effect proximity sensor, so you can check it out with a volt meter. The connector (Right on top at the front of the engine) should hav 8V on one terminal, ground on another, and the third terminal toggles between near ground and about 5V as the gap passes the sensor. A flakey CPS looks like a bad PCM. Been there, done that, got the T shirt.

edwinsmith

Just for grins for those of us with more than idle curiosity into electronic magic here's how the Hall Effect works.

https://en.wikipedia.org/wiki/Hall_effect

Edwin

1stgendodge

Ok, thanks for the info. I don’t have time to test it tonight, but I will test it tomorrow. Any other suggestions would be appreciated.




The info about the issues with the truck is in my thread called 1993 dodge w250 overdrive issues.

If anyone has any other ideas, let me know before I end up having to start throwing parts at it. 👍

Stover93

I just bought a pcm from mymoparparts.com. $200 plus $125 core return. Fixed all of the issues I was having. The main issue was no voltage reg.

edwinsmith

Just out of curiosity, what kind of PCM is on the 89? What kind of problems could I expect if it went haywire. Should I have a spare for the future?

Inquiring minds want to know.

Edwin

oliver foster

Edwin,
You don't have a PCM in that '89. You have a voltage regulator and a little black box roughly under your steering column on the firewall that controls the grid heaters.
I wouldn't worry about it much. You got a Mopar V.R. if I remember so you should be good for a while.

edwinsmith

Thanks Oliver. I DO have the Mopar VR after going through 2 O'Reilly ones that crapped out. I plan to move back to colder climates eventually when the wife retires so I think having the grid heaters is a good thing. If the controller goes out could I wire them up with a push button? Has anyone ever done this?

Do you have a good spare? Are new ones available? I hate not having access to a spare when stuff is becoming unobtanium.

Thanks again.

Edwin

oliver foster

Edwin,
I don't think those black boxes are available new and I doubt the aftermarket with ever "re pop" them as they only used them in '89, '90 and 91.0. By 91.5 they go to the PCM.

Yeah I have spare "black boxes" if you ever need one.
The Mopar VR are the way to go, unless you can find an old OEM VR and even then you should keep a spare in the glove box. The new auto parts store ones are total junk.

Sorry for the slight derail of this useful thread. I am glad you [Stover93] had good luck with a rebuilt PCM as I usually hear horror stories about people you get their PCMs rebuilt. Everything from never getting it back at all, to getting back one in worse shape then the one they sent it.

1stgendodge

Is a ecm the same as a pcm on these trucks?

oliver foster

There is no ECM [Engine Control Module] on the Cummins trucks until the 24V is '98.5.
The 24V have 2 major computers, one on the firewall [PCM] and one [ECM] on the engine behind the injection pump

1stgendodge

On in my truck there is a computer on the left front fender and one behind the glove box. Any idea what the one behind the glove box is?

is the computer on moparparts listed as a ecm, the pcm?