Computer controls

[THuebner]

I did not know where else to post this question, so here goes:

What was the first model year that there is a computer affixed to either the engine or transmission for the Dodge Cummins turbo-diesel pickup trucks?

I am thinking of buying another truck as a project vehicle and would prefer that everything be contolled without a computer chip.

Thanks.

Tom

 

[Beast2B]

the ECM started with the first 24-valve trucks in 1998 (called 98. 5 around here as they made 12- and 24-valve trucks called 98s). The PCM started with the change from the 47rh to the 47re auto trans (96 was the first year... someone chime in)

 

[Joe G.]

The PCM also was used to control OD and torque convertor lockup in the '94 and '95. I think, but not sure, that a PCM was also used for the '89 thru '93 for OD.

 

[PToombs]

PCM started in 91. 5, along with the OD trans.

You can go up to early '98s if you run a manual trans. You don't need a computer to run the grids, or most of the other stuff, 1 wire alternator for charging, etc.

 

[THuebner]

Thanks for replying.

It looks like my truck is the latest model that did NOT come with a computer to control either the (automatic) trans or engine.

That is somthing because part of my interest in another truck was to have overdrive, but it looks like all trucks with an automatic overdrive transmission will have a computer to control the transmission. (I really want to stick with an automatic transmission)

It is also interesting that no 12 valve engines have a computer for engine control but all the 24 valve engines do have a computer.

What is the difference between a PCM and an ECM?

Let me try this: If I want a truck with automatic overdrive and a minimal ammount of computer control "stuff", a 47RH transmission instead of a 518, I should find a '94 or 95 model year truck?

Thanks again.

Tom

 

[LandShark]

I believe you will find 94 and 95 to be the same. I replaced my PCM last year, so learned a few things about them. I was able to drive the truck for 2 weeks with a bad PCM, but it's a pain. Most of the functions of the PCM can be bypassed with a bit of wiring. I only bypassed alternator control and trans lockup. Some other things the PCM controls are: Tach, cruise control, AC, overdrive, grid heaters, water in fuel light and wait to start light.

 

[Joe G.]

I agree with LandShark. The '94 and '95 have the least computer control of the drive train and still has OD. I have mine set up so I control most of the OD and lockup functions with switches. That works pretty good. I am working on an electronic controller to make it shift the way I want without using the PCM and having to control it with switches.

 

[THuebner]

Hi Landshark and Joe G,

Thanks for confirming my thoughts regarding the 94-95 model years having the least computer stuff to deal with in the drive train.

Would someone please fill me in on what PCMs and ECMs are and what the difference between them is? I suppose If I am going to buy a 94 or 95 I should start finding out about what they have on them.

Thanks to all for replying.

Tom

 

[Joe G.]

The PCM is the Powertrain Control Module. All it does is run the transmission and, if it's a gasser, some engine stuff. It also controls things like the alternator and the instrument panel.



The ECM is the Electronic Control Module. It does a lot more stuff in addition to what the PCM does.



I don't think there is a precise definition for either device.

 

[THuebner]

Hi Joe,

Thank you for sending the info.

I have not been able to decuce if the PCM is an actual computer or a electronic switching device of some sort.

Either way it seem some of you fellas have found ways to perform the function(s) of the PCM when they are missing or disabled.

Tom

 

[LandShark]

Hi Joe,
Thank you for sending the info.
I have not been able to decuce if the PCM is an actual computer or a electronic switching device of some sort.
Either way it seem some of you fellas have found ways to perform the function(s) of the PCM when they are missing or disabled.
Tom

I'm also not sure if it's strictly correct to call a PCM a computer (and I have a BS in computer science). The PCM does have logic circuits and solid state switches and some parts of it can to changed (programmed). What does it matter what you call it? The important thing is that it controls a bunch of stuff and it costs about $500 to replace.