Is any one familiar with the serial comm link between the PCM and Cluster and also the ABS/ASR modules?

I am trying to find out info on the comm language and if there communication is transmits only or transmit and receive from each component.

Thanks,
Victor

 

no one?

 

I'm not totally familiar with that particular circuity on the 96's as they have a different PCM and OBDII than my 93. However, you cannot really measure per say the communication between the modules. A FSM and a careful study of the comm. circuits and any info that might be in it will be your best bet.

I'm going to guess and say the PCM and Instrument Cluster (CCM) definitely talk back and forth. The ABS/ASR probably will to based upon how they work.

The comm. language I can only give you very general information. That is not something that any factory service manual will contain, regardless of manufacture. To the best of my knowledge. It is not something that is needed in the automotive repair field. That is mostly for engineering.

Older cars like C4 Corvette like the early C4's and such might use UART communications. This is very basic.

Early to Mid 90's cars use a Multi-Plex network. I believe from looking at the comm. circuitry for my 93 that it uses a combination of UART for things like the Keyless Entry Module and Multi-Plex for the ECM, CCM, ABS/ASR, and the A/C Programmer.

System communicates by applying 5v to he circuitry or applying ground making a square wave signature. In fact, now that I think of it if one had an oscilloscope you could view this comm.

These older systems are slow and have very limited data capabilities. Newer cars like starting mid 2000's have CAN (Car Area Network) with High Speed and Low Speed CAN, much, much higher data capabilities and speeds are very high.

That is the basics of what is going on. Why do you ask about this??
If you have a comm. problem verify continuity on the circuitry in question with all modules disconnected from it. If ok, hook them all back up and remove 1 at a time till you have communication. The last one you disconnected was the faulty module. Verify it has good power and ground, if so, you probably need a new one.

 

I am working on a aftermarket engine management and would like to look into being able to take the required data and send it out to the other modules to keep the functionality of the dash readouts.

You are correct, no fsm will discuss this level of detail, however as the years go on and people reverse engineer the electronics and info leaks out from various sources, sometimes the info become available. Once and a while I've ha the opportunity to speak to design engineer about various things of this nature.

I can run the car with an aftermarket ECM, however I need all the other functions as mentioned to work also to bea successful install.

Victor

 

Yeah, I hear ya. Not sure what to tell you on this one. Good Luck with your project. This is something the average back yard hot rodder just is not able to deal with easily. You need to find an engineer or at least someone familiar with what you are trying to accomplish.

 

Thanks for the reply I am hoping someone may know, it is an obscure peice off information beyond most DIY projects however with the time that has passed is nice the technology was used I am hoping it pops up.

Cheers