Another CCM 41 code
Thread Starter
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
Another CCM 41 code
I have searched quite a bit, but no exact matches. Here goes:
Drove the 92 (bone stock 6spd) hard for about 45 minutes testing brakes suspension and accel. Temps seemed fine. Next day crank but no start. Symptoms:
Sys and security lights flash simultaneously when switched on.
CCM code C41 and H41 (cleared codes via buttons, disconnect batt, fuse) and same codes came back. NO FEDS disable code (51 or 54 iirc)
Module 4(ECM) Err
Module 9(EBCM) Err
C68 climate control code 10 and blinking light.
E/M button doesn't convert.
Service ride control light on.
Service ABS light on.
Readout of ECM codes directly ALDL pins A&B: nothing but code 12
ECM, CCM, A/C and any other fuses I thought might be related tested good.
VATS has been bypassed (spare key without resistor pellet works fine)
The closest search results all mention the FEDS disable code, but not mine. I'm thinking the most likely culprits are:
1. Serial comm wire shorted
2. Dead ECM
3. Dead CCM
Anyone have any suggestions? Or Should I just keep following the FSM steps?
Thanks
Drove the 92 (bone stock 6spd) hard for about 45 minutes testing brakes suspension and accel. Temps seemed fine. Next day crank but no start. Symptoms:
Sys and security lights flash simultaneously when switched on.
CCM code C41 and H41 (cleared codes via buttons, disconnect batt, fuse) and same codes came back. NO FEDS disable code (51 or 54 iirc)
Module 4(ECM) Err
Module 9(EBCM) Err
C68 climate control code 10 and blinking light.
E/M button doesn't convert.
Service ride control light on.
Service ABS light on.
Readout of ECM codes directly ALDL pins A&B: nothing but code 12
ECM, CCM, A/C and any other fuses I thought might be related tested good.
VATS has been bypassed (spare key without resistor pellet works fine)
The closest search results all mention the FEDS disable code, but not mine. I'm thinking the most likely culprits are:
1. Serial comm wire shorted
2. Dead ECM
3. Dead CCM
Anyone have any suggestions? Or Should I just keep following the FSM steps?
Thanks
Le Mans Master
Joined: Jul 2009
Posts: 6,381
Likes: 66
From: SF bay area C.A.
C4 of the Year Finalist
To check codes on a 92 jump A to G and get your readouts on the speedo display. Code 41 is a cylinder select error which is a MEM-CAL error. Check for proper pin contact for MEM-CAL and ECM and make sure locking tabs are secure. You will get all kinds of codes if they are not.
Last edited by kimmer; Sep 7, 2012 at 08:33 AM.
Thread Starter
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
A&G is what gives me code C41 and H41 on module 1(CCM) and Err for both module 4(ECM) and module 9(EBCM). By jumping pins A&B (ECM directly) the CEL flashes nothing but code 12s. I did check and reseat the MEM-CAL and it is secure. I am only getting CCM code 41- loss of serial communication.
By the way, my service ABS light is NOT on, but rather the Service ASR is lit up (my mix-up).
By the way, my service ABS light is NOT on, but rather the Service ASR is lit up (my mix-up).
Intermediate
Joined: Aug 2012
Posts: 26
Likes: 1
Sounds like I am chasing the same problem you are. You say you unplugged the ebcm and the ecm? I just unpluged the ebcm. The car still would not start. I have about decided to replace my ecm. I did this after talking to a mechanic, he told me to unplug just the ebcm to see if problem went away.
Thread Starter
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
If the EBCM wasn't showing Err also, I would probably suspect and replace the ECM. What I don't know is this:
if the CCM can't communicate with the ECM, would that also prevent the CCM from communicating with the EBCM?
Also, if you can jump terms A&B and read ECM codes 12, does that really indicate an ECM is functioning properly?
Would a Tech1 be able to determine?
Is there a way to test the serial comm link without tearing into the dash?
if the CCM can't communicate with the ECM, would that also prevent the CCM from communicating with the EBCM?
Also, if you can jump terms A&B and read ECM codes 12, does that really indicate an ECM is functioning properly?
Would a Tech1 be able to determine?
Is there a way to test the serial comm link without tearing into the dash?
Intermediate
Joined: Aug 2012
Posts: 26
Likes: 1
Wish I could be of more help c4. I just got my manuals yesterday and am trying to figure out this stuff too. I work as a Industrial Electrician,troubleshooting equipment, but this vette is so far blowing me away. Just takes time to understand the way everything works together I guess.
But as to your problem, when you have multple problems in a complicated system it almost always goes back to one simple problem. Finding that is the trick. Our cars have well known issues with the ECM. Sorry I cant be of more help right now.
But as to your problem, when you have multple problems in a complicated system it almost always goes back to one simple problem. Finding that is the trick. Our cars have well known issues with the ECM. Sorry I cant be of more help right now.
Melting Slicks
Joined: Jul 1999
Posts: 3,214
Likes: 101
From: Decatur, Alabama
After you check the obvious, there is a junction on top of dash near under defrost vent that connect the 5.0 volt signal (its a data line not a 12 volt on off) that gets corrided and can cause a code .
pull upper dash pad at last resort and visually inspect the junction. It a LITTLE closter to passenger side near windshield
pull upper dash pad at last resort and visually inspect the junction. It a LITTLE closter to passenger side near windshield
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Thread Starter
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
So, it appears the FSM has the CCM green connector orientation pictured incorrectly (8A-202-17). I do have a short to ground on CKT 800 (serial line). One thing I also just noticed: the AC fuse under hood (under the coolant reservoir on the pass side) blows. I noticed it was blown, replaced it, and now it's blown again. I don't know when it originally blew, because I found it after the last time the car ran.
So in short, I'm dealing with circuit 800 (serial comm line) shorted to ground, and the under-hood AC fuse keeps blowing. Thoughts on where to start looking for the short?????
So in short, I'm dealing with circuit 800 (serial comm line) shorted to ground, and the under-hood AC fuse keeps blowing. Thoughts on where to start looking for the short?????
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
According to this site, you should be shorting A to G to show error codes:
http://corvettephotographs.com/c4vettes/codes.htm
Your numbers and their interpretation don't match this list:
http://forums.corvetteforum.com/1576116036-post35.html
http://corvettephotographs.com/c4vettes/codes.htm
Your numbers and their interpretation don't match this list:
http://forums.corvetteforum.com/1576116036-post35.html
Thread Starter
Pro
Joined: Dec 2000
Posts: 555
Likes: 2
From: RDU NC
According to this site, you should be shorting A to G to show error codes:
http://corvettephotographs.com/c4vettes/codes.htm
Your numbers and their interpretation don't match this list:
http://forums.corvetteforum.com/1576116036-post35.html
http://corvettephotographs.com/c4vettes/codes.htm
Your numbers and their interpretation don't match this list:
http://forums.corvetteforum.com/1576116036-post35.html
One of the first things I did months ago per your advice was check the grounds, and they all were tight and clean.
I followed the diag chart for CCM Error code 41 and came to the conclusion of CKT 800 (serial data lines) shorted to ground. I found the short last night! I haven't put it all back together again yet, but it was blatantly obvious and no more short to ground [see pic]. I'm going to write up a final sequence of events/troubleshooting etc when this is all over! This was the wire bundle to/from the C68 AC programmer under the driver side dash, and they seem to have been pinched somewhere along steering column:
