What computer module depends on what other in a '91
Thread Starter
Melting Slicks
Joined: Dec 2008
Posts: 2,772
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From: Mystic CT
What computer module depends on what other in a '91
s far as I know I have the following computer modules but curious which one depends on what others.
ECM
CCM
C68
ABS
FX3
VATS seems to run through CCM unless missing something.
Looking to simplify things but without knowing what relies on what decisions are hard to make. With all 25 year old through hold circuit boards reliability is sort of a joke.
ECM
CCM
C68
ABS
FX3
VATS seems to run through CCM unless missing something.
Looking to simplify things but without knowing what relies on what decisions are hard to make. With all 25 year old through hold circuit boards reliability is sort of a joke.
Thread Starter
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
I have had much more trouble with thru hole in the after market auto electronics and zero with SMT. Vibration seems to shake the thru hole parts to failure in my experience. I always attributed to the distance from the part off the board and greater mass of the parts creating a longer lever arm to stress the solder joint.
Le Mans Master
Joined: Oct 2002
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From: Las Vegas - Just stop perpetuating myths please.
Not to sure what your are asking? Which module depends on another is a very broad question. Which ones communicate can be seen on the 1990-1991 engine wiring diagram and you can find one here: https://wiki.bentleypublishers.com/p...ageId=17989640.
Those modules will communicate w/serial data but not like the Ethernet packets, segments and frames. If want to intercept and interpret the serial data you can use some other application software like "Bit Shark" but i doubt you want to go there. What the logical diagrams (protocol/topology?) look like for each module you would have to ask general motors to provide them.
Now the software has been hacked as thats where all the tuner software came/comes from. But i imagine that would have to be your career specialty for enough expertise rather than a hobby. Best option is to use the diagnostic software from GM or aftermarket to find your problems.
I think your asking for something only the GM engineering department can provide.
Those modules will communicate w/serial data but not like the Ethernet packets, segments and frames. If want to intercept and interpret the serial data you can use some other application software like "Bit Shark" but i doubt you want to go there. What the logical diagrams (protocol/topology?) look like for each module you would have to ask general motors to provide them.
Now the software has been hacked as thats where all the tuner software came/comes from. But i imagine that would have to be your career specialty for enough expertise rather than a hobby. Best option is to use the diagnostic software from GM or aftermarket to find your problems.
I think your asking for something only the GM engineering department can provide.
Thread Starter
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
Not to sure what your are asking? Which module depends on another is a very broad question. Which ones communicate can be seen on the 1990-1991 engine wiring diagram and you can find one here: https://wiki.bentleypublishers.com/p...ageId=17989640.
Those modules will communicate w/serial data but not like the Ethernet packets, segments and frames. If want to intercept and interpret the serial data you can use some other application software like "Bit Shark" but i doubt you want to go there. What the logical diagrams (protocol/topology?) look like for each module you would have to ask general motors to provide them.
Now the software has been hacked as thats where all the tuner software came/comes from. But i imagine that would have to be your career specialty for enough expertise rather than a hobby. Best option is to use the diagnostic software from GM or aftermarket to find your problems.
I think your asking for something only the GM engineering department can provide.
Those modules will communicate w/serial data but not like the Ethernet packets, segments and frames. If want to intercept and interpret the serial data you can use some other application software like "Bit Shark" but i doubt you want to go there. What the logical diagrams (protocol/topology?) look like for each module you would have to ask general motors to provide them.
Now the software has been hacked as thats where all the tuner software came/comes from. But i imagine that would have to be your career specialty for enough expertise rather than a hobby. Best option is to use the diagnostic software from GM or aftermarket to find your problems.
I think your asking for something only the GM engineering department can provide.
Advanced
Joined: Jul 2013
Posts: 87
Likes: 13
From: Tampa Bay area Florida
I have had much more trouble with thru hole in the after market auto electronics and zero with SMT. Vibration seems to shake the thru hole parts to failure in my experience. I always attributed to the distance from the part off the board and greater mass of the parts creating a longer lever arm to stress the solder joint.
Thread Starter
Melting Slicks
Joined: Dec 2008
Posts: 2,772
Likes: 64
From: Mystic CT
<<<<< -- EE with over 40 years experience with the design of electronic assemblies and circuit boards for a major manufacturer of industrial control products. That included wire-to-wire, thru-hole, and SMT. I know the reliability factors, I was also the QA manager for 10 years. The problem you experienced are probably due to the "aftermarket" industry's lower standards.
Advanced
Joined: Jul 2013
Posts: 87
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From: Tampa Bay area Florida
As I understand it, it goes like this:
The CCM won't work without a handshake from the ECM at ignition-on time. The ECM works alone but depends on the CCM for VATS information. But that might be bypassed or substituted to eliminate the CCM. The ABS uses signals from the CCM to determine vehicle speed, so it can compare that with the individual wheel speeds. I don't think the suspension control module needs anything from the others because it gets vehicle speed directly from the transmission sensor. I think the HVAC module needs vehicle speed from the CCM but I don't know what happens if it isn't present.
The CCM won't work without a handshake from the ECM at ignition-on time. The ECM works alone but depends on the CCM for VATS information. But that might be bypassed or substituted to eliminate the CCM. The ABS uses signals from the CCM to determine vehicle speed, so it can compare that with the individual wheel speeds. I don't think the suspension control module needs anything from the others because it gets vehicle speed directly from the transmission sensor. I think the HVAC module needs vehicle speed from the CCM but I don't know what happens if it isn't present.
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The CCM does hold and retain the ODOMETER, the CCM also controls the entire LCD display in the cluster. Runs it? No I'd say but is responsible for the display and control. The VSS in '90+ cars first stop is the ECM with splices that directly go to SRCM - FX3 (if equipped), ECM data is sent simultaneously to the SCVC (radio), Cruise and CCM.
Last edited by WVZR-1; Sep 5, 2016 at 05:56 PM.
Thread Starter
Melting Slicks
Joined: Dec 2008
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From: Mystic CT
Does that make the ABS stand alone? If I understand the C68 and FX3 were options so can be safely deleted if needed. I have an after market radio that uses nothing from the original short of antenna so no issues there. Vats can be bypasses with programing and wiring changes.
It would seem the only way to get to ECM only and lose the CCM is to have a speedometer and fuel gauge solution along with vats programing or aftermarket ECM that has no VATS.
Or as usual am I missing something still?
It would seem the only way to get to ECM only and lose the CCM is to have a speedometer and fuel gauge solution along with vats programing or aftermarket ECM that has no VATS.
Or as usual am I missing something still?
Race Director
Joined: Mar 1999
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From: Bartlett Illinois
You can do VATs delete logic on the ECM (within the MEMCAL). That should suffice the ECM to start. I do know that the 91-90 EBCM (ABS ECM) is the same, I also know that the 89-90 ABS harness is the same (1991 changed due to front sensor redesign).
I can say that a 1991 ECM and 1991 CCM will work without the ABS Serial connection. When I converted my 89 to a 1991 dash, I used a 1991 CCM to get the cluster display to work correctly, but I left the 1989 EBCM in the car, without issues or code or anything being displayed and the ABS worked as designed.
I can say that a 1991 ECM and 1991 CCM will work without the ABS Serial connection. When I converted my 89 to a 1991 dash, I used a 1991 CCM to get the cluster display to work correctly, but I left the 1989 EBCM in the car, without issues or code or anything being displayed and the ABS worked as designed.
Thread Starter
Melting Slicks
Joined: Dec 2008
Posts: 2,772
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From: Mystic CT
Did you have C68 or was that not available in you car? If so did that work ok?
I would think a simple PIC or other computer could easily drive the LCD and Vats delete solves that. ABS seems like stand alone as does FX3 and C68.
My plan here digging through this is the fatal day the CCM goes belly up. They are rare expensive and require programming with tools long since packed away at dealers. I asked my local dealer about checking the ABS and cycling it for me and the reply was that stuff was packed away ages ago and there are few that even remember how to use it.
I would think a simple PIC or other computer could easily drive the LCD and Vats delete solves that. ABS seems like stand alone as does FX3 and C68.
My plan here digging through this is the fatal day the CCM goes belly up. They are rare expensive and require programming with tools long since packed away at dealers. I asked my local dealer about checking the ABS and cycling it for me and the reply was that stuff was packed away ages ago and there are few that even remember how to use it.
Race Director
Joined: Mar 1999
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From: Bartlett Illinois
I had C68.. it worked fine. I am not sure if the CCM does anything with the HVAC. my 1990 ZR-1 has C60, so I too expect that if the CCM goes belly up I could go to aftermarket gauges and call it good