Need some input on CCM code 41
Thread Starter
Racer
Joined: Jul 2002
Posts: 285
Likes: 1
From: Edmond Oklahoma
Need some input on CCM code 41
92, LT1, Auto, 120K, about 3 K on rebuild.
Drove it home 2 weeks ago, everything fine. Went to move the car yesterday, and fired/immediately dies, with SYS displayed. Was able to "sort of" make it run (rough, terrible exhaust odor, security lamp flashing) by pumping accelerator, as I read in another thread.
Scanned for codes via jumpering A/G at ALDL and retrieved both current and history 41 from CCM
Using the FSM flow chart, ran through the tests (gotta LOVE the CCM location), and found no opens/shorts.
Car shows following symptoms:
Starts/immediately dies
C68 control head LED flashing, and unresponsive to eng/met toggling (though cluster ltr/gal and mph/kph display does switch)
Service ASR lamp illuminated
When polling CCM via A/G ALDL jumper, displays C41 and H41 in module 1, ERR in module 4, and ERR in module 9
Jumpering A/B at the ALDL retrieved only code 12 from ECM
Tried removing and reseating EPROM in ECM with no difference. Odd note here...when I removed the first screw from the access cover, there was a hissing that appeared to be air escaping from ECM...perhaps because it is 105 degrees?
I would make the assumption (I know
) that this indicates an ECM issue...which brings me to the following dilemma:
I (again) assume that since there were no codes when polling the ECM, that the EPROM/MEMCAL is not damaged? I gather that if it were, a DTC 51 would be set. How can one be sure that the ECM is the issue? And, can one assume there is some damage to the ECM internally, or is it more likely that there is another issue? Any way to rule in/out the EPROM?
Then of course, there's the whole "lack of 92/93 ECM availability" issue
I don't mind sending the ECM out for a rebuild, but would hate to spend the money/time if it's something else.
I think I have pretty well exhausted the info I found via search here, but perhaps I missed something.
Many thanks to anybody that can expand on this.
Drove it home 2 weeks ago, everything fine. Went to move the car yesterday, and fired/immediately dies, with SYS displayed. Was able to "sort of" make it run (rough, terrible exhaust odor, security lamp flashing) by pumping accelerator, as I read in another thread.
Scanned for codes via jumpering A/G at ALDL and retrieved both current and history 41 from CCM
Using the FSM flow chart, ran through the tests (gotta LOVE the CCM location), and found no opens/shorts.
Car shows following symptoms:
Starts/immediately dies
C68 control head LED flashing, and unresponsive to eng/met toggling (though cluster ltr/gal and mph/kph display does switch)
Service ASR lamp illuminated
When polling CCM via A/G ALDL jumper, displays C41 and H41 in module 1, ERR in module 4, and ERR in module 9
Jumpering A/B at the ALDL retrieved only code 12 from ECM
Tried removing and reseating EPROM in ECM with no difference. Odd note here...when I removed the first screw from the access cover, there was a hissing that appeared to be air escaping from ECM...perhaps because it is 105 degrees?
I would make the assumption (I know
) that this indicates an ECM issue...which brings me to the following dilemma:I (again) assume that since there were no codes when polling the ECM, that the EPROM/MEMCAL is not damaged? I gather that if it were, a DTC 51 would be set. How can one be sure that the ECM is the issue? And, can one assume there is some damage to the ECM internally, or is it more likely that there is another issue? Any way to rule in/out the EPROM?
Then of course, there's the whole "lack of 92/93 ECM availability" issue
I don't mind sending the ECM out for a rebuild, but would hate to spend the money/time if it's something else.
I think I have pretty well exhausted the info I found via search here, but perhaps I missed something.
Many thanks to anybody that can expand on this.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
If youre only getting 12 from the ECM, its not that, unless its the communication to the CCM part of the ECM.
Its been a long time since ive diagnosed this sort of issue, but there should be a serial connection there between the ECM and CCM?
Pull that CCM out and have a look at the condition of the internals, check the cable between there and the ECM ( seems like youve done this bit ), check the condition of the plugs and clean them all up, check all the fuses, and see what you come up with then.
When you look inside the ECM, what is the condition of the capacitors in there like? Have you got another friend with a 92 or 93 that you can test their ECM or CCM in your car?
Its been a long time since ive diagnosed this sort of issue, but there should be a serial connection there between the ECM and CCM?
Pull that CCM out and have a look at the condition of the internals, check the cable between there and the ECM ( seems like youve done this bit ), check the condition of the plugs and clean them all up, check all the fuses, and see what you come up with then.
When you look inside the ECM, what is the condition of the capacitors in there like? Have you got another friend with a 92 or 93 that you can test their ECM or CCM in your car?
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Found this earlier post, see rodj's post #4, seems to be several tips there for diagnosis, good luck.
http://forums.corvetteforum.com/c4-t...-no-start.html
http://forums.corvetteforum.com/c4-t...-no-start.html
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Thread Starter
Racer
Joined: Jul 2002
Posts: 285
Likes: 1
From: Edmond Oklahoma
Yes, I've read all those threads.
I had already checked all the fuses, I will have to recheck grounds at this point...although checking the main ground at the block will be interesting as the car is outside on a sloped driveway.
Case: yes there SHOULD be a serial connection, but the 41 indicates that it has been lost.
Guess I'll reinstall the CCM and see if the movement of the connectors has perhaps cleaned a film from the connections.
I had already checked all the fuses, I will have to recheck grounds at this point...although checking the main ground at the block will be interesting as the car is outside on a sloped driveway.
Case: yes there SHOULD be a serial connection, but the 41 indicates that it has been lost.
Guess I'll reinstall the CCM and see if the movement of the connectors has perhaps cleaned a film from the connections.
Last edited by a454corvette; Aug 6, 2011 at 10:32 AM.
Racer
Joined: Mar 2011
Posts: 304
Likes: 0
From: Victoria Australia
I am battling the exact same problem the SYS displaying every so often in my 1990 since I got it. My car starts and drives fine. Even during cruise the SYS will sometimes disappear for 15-20minutes but only to come back.
Problem is definitely intermittent. Very long process to diagnose, check grounds, check fuse and check wiring to cluster.
Problem is definitely intermittent. Very long process to diagnose, check grounds, check fuse and check wiring to cluster.
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Yes, I've read all those threads.
I had already checked all the fuses, I will have to recheck grounds at this point...although checking the main ground at the block will be interesting as the car is outside on a sloped driveway.
Case: yes there SHOULD be a serial connection, but the 41 indicates that it has been lost.
Guess I'll reinstall the CCM and see if the movement of the connectors has perhaps cleaned a film from the connections.
I had already checked all the fuses, I will have to recheck grounds at this point...although checking the main ground at the block will be interesting as the car is outside on a sloped driveway.
Case: yes there SHOULD be a serial connection, but the 41 indicates that it has been lost.
Guess I'll reinstall the CCM and see if the movement of the connectors has perhaps cleaned a film from the connections.
I am battling the exact same problem the SYS displaying every so often in my 1990 since I got it. My car starts and drives fine. Even during cruise the SYS will sometimes disappear for 15-20minutes but only to come back.
Problem is definitely intermittent. Very long process to diagnose, check grounds, check fuse and check wiring to cluster.
Problem is definitely intermittent. Very long process to diagnose, check grounds, check fuse and check wiring to cluster.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Yes, I've read all those threads.
I had already checked all the fuses, I will have to recheck grounds at this point...although checking the main ground at the block will be interesting as the car is outside on a sloped driveway.
Case: yes there SHOULD be a serial connection, but the 41 indicates that it has been lost.
Guess I'll reinstall the CCM and see if the movement of the connectors has perhaps cleaned a film from the connections.
I had already checked all the fuses, I will have to recheck grounds at this point...although checking the main ground at the block will be interesting as the car is outside on a sloped driveway.
Case: yes there SHOULD be a serial connection, but the 41 indicates that it has been lost.
Guess I'll reinstall the CCM and see if the movement of the connectors has perhaps cleaned a film from the connections.
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Thread Starter
Racer
Joined: Jul 2002
Posts: 285
Likes: 1
From: Edmond Oklahoma
Update
In the interest of assisting others down the line, here is where I am as of this morning
Later yesterday, as a cool front moved through, I began reassembling the car. I plugged and unplugged the CCM connectors several times, then made sure all ECM/CCM connectors were in place, Cranked the car, and fired right up and idled as though nothing ever had changed. It began to rain, so I called it a day.This morning, I disco'd the battery to clear codes, and reassembled the remainder of the removed parts. Checked for codes, and all were clear.
At this point the only conclusion I can draw is that after 18+ years, the connections became compromised by the film that typically builds up inside older cars on things like window switches, etc. I did find some sort of aftermarket antenna (I presume it was a paging type alarm antenna) stuffed up above the CCM, which has been removed. I'm guardedly optimistic that the issue has been resolved in light of the wiring harness passing the diagnostic process. Hoping the removing and reseating the various component connections established a better connection.
I would be remiss if I did not extend my thanks to those who have posted advice, those that have posted their prior experiences, and those who PM'd with generous offers of assistance. I truly appreciate every piece of input.
Thanks to all
Brian
In the interest of assisting others down the line, here is where I am as of this morning
Later yesterday, as a cool front moved through, I began reassembling the car. I plugged and unplugged the CCM connectors several times, then made sure all ECM/CCM connectors were in place, Cranked the car, and fired right up and idled as though nothing ever had changed. It began to rain, so I called it a day.This morning, I disco'd the battery to clear codes, and reassembled the remainder of the removed parts. Checked for codes, and all were clear.
At this point the only conclusion I can draw is that after 18+ years, the connections became compromised by the film that typically builds up inside older cars on things like window switches, etc. I did find some sort of aftermarket antenna (I presume it was a paging type alarm antenna) stuffed up above the CCM, which has been removed. I'm guardedly optimistic that the issue has been resolved in light of the wiring harness passing the diagnostic process. Hoping the removing and reseating the various component connections established a better connection.
I would be remiss if I did not extend my thanks to those who have posted advice, those that have posted their prior experiences, and those who PM'd with generous offers of assistance. I truly appreciate every piece of input.
Thanks to all
Brian
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Brian, its not a problem mate, happy to have helped.
Resistance is a big problem when dealing with extra low voltage DC connections, so i reckon if it happens again, it hit it with some good spray on contact cleaner.
Resistance is a big problem when dealing with extra low voltage DC connections, so i reckon if it happens again, it hit it with some good spray on contact cleaner.
