1994 corvette CCM issue
Thread Starter
Heel & Toe
Joined: Oct 2023
Posts: 15
Likes: 1
1994 corvette CCM issue
Hello I have a problem that was intermittent and now has become permanent and the car is stranded, the car used to start and drive and sometimes the car security system used to stay on and the car dies after few seconds of running, I could hear the gas pump working when I pass the switch, we checked for codes and got H51 which I think is ccm prom, I do not know what to do with this car nobody seems to know what's going on. any suggestions to where can I send the ccm to have it repaired and remove the vat?
Racer
Joined: Jul 2022
Posts: 495
Likes: 163
From: Wilmington,Delaware
Hello I have a problem that was intermittent and now has become permanent and the car is stranded, the car used to start and drive and sometimes the car security system used to stay on and the car dies after few seconds of running, I could hear the gas pump working when I pass the switch, we checked for codes and got H51 which I think is ccm prom, I do not know what to do with this car nobody seems to know what's going on. any suggestions to where can I send the ccm to have it repaired and remove the vat?
May want to see if someone on the board has a spare one for sale. You could have it sent out to PCM FOR LESS for trouble shooting. I had them turn the VATS off on my 96.
Racer
Joined: Jul 2022
Posts: 495
Likes: 163
From: Wilmington,Delaware
Safety Car
Joined: Jun 2010
Posts: 4,564
Likes: 1,676
It is not the CCM that is having issues, it is the PCM. The only other time I have seen this failure was in a Camaro. The fix is a replacement PCM.
You are correct, there is no “New” only new to you. Hopefully your current programming can be copied, but no big deal if it can’t be. It can be recreated. Try to find a PCM that the seller can flash for you. So it arrives ready to go.
You are correct, there is no “New” only new to you. Hopefully your current programming can be copied, but no big deal if it can’t be. It can be recreated. Try to find a PCM that the seller can flash for you. So it arrives ready to go.
Safety Car
Joined: Jun 2010
Posts: 4,564
Likes: 1,676
Code H51 can be present in both the CCM and the PCM. Using the onboard diagnostics, the CCM is module 1 and the PCM is Module 4. It is important to know which module H51 is in. (In this case, Code H51 is most likely in Module 1, the CCM.)
The CCM H51 means "incorrect key resistance detected". When this happens the engine will not crank, and it will not run because the PCM does not allow fuel injection.
If the CCM detects "incorrect key resistance" while the engine is running, the SECURITY light is illuminated solid-on.
The key cylinder has contacts that connect the resistor pellet in the key to the wiring in the car. There are two little wires from the key cylinder that are 'flexed' every time the cyl is rotated. These wires can become intermittent, and eventually sever entirely.
The OP's symptoms highlighted in blue above suggest that the wires for the key cyl have broken. He can replace the cyl assembly, or use a resistor bypass at the base of the steering column.
The CCM H51 means "incorrect key resistance detected". When this happens the engine will not crank, and it will not run because the PCM does not allow fuel injection.
If the CCM detects "incorrect key resistance" while the engine is running, the SECURITY light is illuminated solid-on.
The key cylinder has contacts that connect the resistor pellet in the key to the wiring in the car. There are two little wires from the key cylinder that are 'flexed' every time the cyl is rotated. These wires can become intermittent, and eventually sever entirely.
The OP's symptoms highlighted in blue above suggest that the wires for the key cyl have broken. He can replace the cyl assembly, or use a resistor bypass at the base of the steering column.
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Thread Starter
Heel & Toe
Joined: Oct 2023
Posts: 15
Likes: 1
the car cranks,engine starts and then shut off after few seconds and the security lights sometimes is solid and sometimes blinks, so if it was not detecting the key would not crank that what I was told,right or wrong?
Thread Starter
Heel & Toe
Joined: Oct 2023
Posts: 15
Likes: 1
and update see if it helps to figure out what's going on?the car started today and engine ran cut engine off and again turning the ignition switch the security blinked and when started the engine the security light stayed solid and engine shut off after few second, we opened the compartment under the steering and moved around some cables removed the fuse on the aftermarket alarm and when we put the fuse back something click on the doors and the cars started fine, the fault happened in different episodes but the was no way to replicate it in a way that we could pin oint the issue.
again I bridge connector for retrieving the codes and show H51 on module. if the wires in the ignition switch were the broken as suggested by chumpvette it should have started again i guess. Now can I send the ECM PCM te have the VAT disabled? I am back to square one but the car starts sometimes.
again I bridge connector for retrieving the codes and show H51 on module. if the wires in the ignition switch were the broken as suggested by chumpvette it should have started again i guess. Now can I send the ECM PCM te have the VAT disabled? I am back to square one but the car starts sometimes.