C5 Corvette will not start-requires resetting BCM
#1
C5 Corvette will not start-requires resetting BCM
Hi All,
If I leave my 1999 C5 Corvette off for a while after driving, it will not start. I get the Engine light on but when I turn the key to start all lights turn off and it does not crank. If I pull fuse 9 (BCM A) on the IP fuse box it will start again.
Any ideas?
I did recently change out all ignition cables and now I get high misfire counts in Torque test results (TID:$0c CID:$20 and TID: $0c CID:$30, all above 64,208 count, max is 234 for each). Bad ignition wire connections? Could this cause the BCM to refuse to allow the engine to start? I get no other ECU code or DTC codes.
Thanks.
Note: I do not recall seeing any of these test codes occurring before changing out the ignition cables.
If I leave my 1999 C5 Corvette off for a while after driving, it will not start. I get the Engine light on but when I turn the key to start all lights turn off and it does not crank. If I pull fuse 9 (BCM A) on the IP fuse box it will start again.
Any ideas?
I did recently change out all ignition cables and now I get high misfire counts in Torque test results (TID:$0c CID:$20 and TID: $0c CID:$30, all above 64,208 count, max is 234 for each). Bad ignition wire connections? Could this cause the BCM to refuse to allow the engine to start? I get no other ECU code or DTC codes.
Thanks.
Note: I do not recall seeing any of these test codes occurring before changing out the ignition cables.
Last edited by paultissue; 06-21-2019 at 01:01 AM. Reason: Add Torque Screen Capture
#2
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St. Jude Donor '08
This has happened to a few C5 owners and here is a very good post that describes what it is and how to overcome it: Its a BCM WAKE/SLEEP issue.
Last edited by Bill Curlee; 06-21-2019 at 12:01 PM.
#3
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St. Jude Donor '08
I couldn't get the post to cut and paste into the reply. Damn Forum! (*^*&%
Provide an e-mail and I will send it to you
Provide an e-mail and I will send it to you
#4
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St. Jude Donor '08
When ever you disconnect and reconnect the battery, the BCM/PCm and other modules can and will throw random DTCs Just clear them and monitor.
BC
BC
#5
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Location: Anthony TX
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St. Jude Donor '08
- BCM Wake/Sleep Issue: http://forums.corvetteforum.com/c5-t...ol-module.html http://forums.corvetteforum.com/c5-t...tible-bcm.html
HA!!!! Fixed it.. Check out this post.
HA!!!! Fixed it.. Check out this post.
#6
I am not sure if my issue is a "no-wake-up BCM" problem. I do get interior lights upon entry and trunk hatch release works with the key fob.
The only symptom is that it will not crank. Removing and then replacing IP fuse #9 allows it to crank. I will re-check the TDR.
Update: TDR is good. Engine has cranked and started several times since, including overnight. Testing ignition wires to see if there is a bad connection, high resistance, or moisture.
The only symptom is that it will not crank. Removing and then replacing IP fuse #9 allows it to crank. I will re-check the TDR.
Update: TDR is good. Engine has cranked and started several times since, including overnight. Testing ignition wires to see if there is a bad connection, high resistance, or moisture.
Last edited by paultissue; 06-22-2019 at 03:27 PM.
#7
Unfortunately, it will not crank or start again. :-( So this issue is intermittent.
DTC shows "A6-SCM NO COMM." and if I try a couple times more to get the DTCs, it shows 5 codes for A6-SCM:
B2605 Seat Front Vertical Position Sensor Failure
U1255 Serial Data Line Malfunction
U1016 Loss of Communications with PCM
U1160 Loss of Communications with LDCM
U1064 Loss of Communications with BCM
I do not get any other codes in the other categories.
So, It seems like bad comms/serial data issues. Could this be a symptom of the "Wake/Sleep" issue? Or is this just some bad connections somewhere? The trunk hatch release on the fob still works and the interior lights do light up on entry. Basically, I see no other symptoms besides these codes and the fact the engine will not crank/start. I have not reset the BCM.
Any thoughts?
Thanks.
Update: I created a switch for fuse #9 by taking a blown 10A fuse and soldering on some leads then adding some terminals to allow attachment of good 10A fuse and toggle switch. So, if I encounter this situation again I can toggle the switch for a moment to disconnect the circuit and then turn it back on. I'll post an update if this works and/or if I find I have to use this on fuse #25 instead. I am guessing that fuse #9 is a low power circuit for the BCM where #25 (and #22 and #23) may be higher power since they are labeled as related to ignition. The couple of times this "no crank" condition occurred, pulling #9 did the trick so I assume it is okay to use it for the "wake" trick. Note: I am able to start my C5 even with this toggled on (closed) or off (open). So I am not sure exactly what fuse #9 controls. But it does "wake" the BCM upon removal/reinsert.
Update #2: Toggling IP fuse #9 did not seem to work. So I connected the switch to IP fuse #25. It worked at first but subsequent times when the car would not start it did not work. If I waited a while (10 or 15 seconds between crank attempts) it did start again. So this may not be a sleep issue but some other intermittent problem. Maybe a bad solder connection on the BCM or a bad connection somewhere? I reset the DTC codes and will wait for another non-crank condition to see what new codes are thrown.
Update #3: The issue returned after a few weeks. Toggling fuse #25 had no effect. Wiggling connectors on BCM enabled it to start again.
Codes were:
U1096 Loss of Communications with IPC
U1064 Loss of Communications with BCM
U1016 Loss of Communications with PCM
DTC shows "A6-SCM NO COMM." and if I try a couple times more to get the DTCs, it shows 5 codes for A6-SCM:
B2605 Seat Front Vertical Position Sensor Failure
U1255 Serial Data Line Malfunction
U1016 Loss of Communications with PCM
U1160 Loss of Communications with LDCM
U1064 Loss of Communications with BCM
I do not get any other codes in the other categories.
So, It seems like bad comms/serial data issues. Could this be a symptom of the "Wake/Sleep" issue? Or is this just some bad connections somewhere? The trunk hatch release on the fob still works and the interior lights do light up on entry. Basically, I see no other symptoms besides these codes and the fact the engine will not crank/start. I have not reset the BCM.
Any thoughts?
Thanks.
Update: I created a switch for fuse #9 by taking a blown 10A fuse and soldering on some leads then adding some terminals to allow attachment of good 10A fuse and toggle switch. So, if I encounter this situation again I can toggle the switch for a moment to disconnect the circuit and then turn it back on. I'll post an update if this works and/or if I find I have to use this on fuse #25 instead. I am guessing that fuse #9 is a low power circuit for the BCM where #25 (and #22 and #23) may be higher power since they are labeled as related to ignition. The couple of times this "no crank" condition occurred, pulling #9 did the trick so I assume it is okay to use it for the "wake" trick. Note: I am able to start my C5 even with this toggled on (closed) or off (open). So I am not sure exactly what fuse #9 controls. But it does "wake" the BCM upon removal/reinsert.
Update #2: Toggling IP fuse #9 did not seem to work. So I connected the switch to IP fuse #25. It worked at first but subsequent times when the car would not start it did not work. If I waited a while (10 or 15 seconds between crank attempts) it did start again. So this may not be a sleep issue but some other intermittent problem. Maybe a bad solder connection on the BCM or a bad connection somewhere? I reset the DTC codes and will wait for another non-crank condition to see what new codes are thrown.
Update #3: The issue returned after a few weeks. Toggling fuse #25 had no effect. Wiggling connectors on BCM enabled it to start again.
Codes were:
U1096 Loss of Communications with IPC
U1064 Loss of Communications with BCM
U1016 Loss of Communications with PCM
Last edited by paultissue; 07-09-2019 at 04:49 PM. Reason: Update about IP fuse #25 not issue...loose connectors somewhere.