I have the Chilton repair manual that covers my 1992 Dodge Ram. It has no useful information about the engine controller module. Is there any documentation explaining how the PCM works, what its inputs are and what voltage ranges they should be, what its outputs are, etc., that is available to the public? For instance, my Maintenance Required light stays on and the code is 45 which means short or open in the overdrive circuit. The Chiltons shows five circuits leaving the PCM and going to the transmission but truncates each circuit giving no information as to what components those five circuits go to. My transmission is the standard issue 3 speed auto and doesn't even have overdrive. If I knew which circuit is causing the code perhaps I could correct it and get rid of that perpetual idiot light. Then when it comes on I would know I have a new problem. Right now I have no way of knowing if the light is the same old same old or if something new has happened. The transmission is shifting fine so the code has to be some phantom issue but it could be effecting the PCM, performance, fuel economy, etc. Without any guidelines I'm wandering around in the dark.

 

do you know what transmisions you have? i think by 92 most transmisions being used had overdrive. the a-500 and a-518 have overdrive.

 

The Equipment Identification tag underneath the hood states: Code no. DGG 3SPD AUTO TRANS A998/A99. I have'nt found anything that states whether that unit has an overdrive but there is nothing on the indicator but L-2-D. Usually an overdrive scenario offers L-D-O or something like that.

 

A998 - 31RH:

3 --- 3 speed
1 --- relative torque capacity
R --- rear wheel drive
H --- hydraulic shift

Yep - its a 3 speed. No overdrive.

 

You will probably have to hit ebay and find a factory service manual.