12/01/2005


Mr. Watson - we have your vehicle running - when it is cut off hot it will not restart - we are
losing communication with the ccm you provided (when hot).Greg has a couple more test to
confirm that this is the failing part.

 

lets think about this for a moment... once these things start, the CCM does nothing. Heat has no effect on the CCM, cause it's inside the dash, away from engine heat.

I am not buying this for one moment.

some more thoughts...

1) What about the ignition control module - it's the box under the coil that amplifies the voltage so the coil can fire. JetJockey93 had a killer problem, much like this, due to a bad connector to the module.

2) The prom chip. That would be more prone to heat related problems than the CCM.

3) Has the circuit that connects the ECM to the CCM been tested?

4) back to the computers... what happens if the ECM or CCM are cooled - a shot of cold air from a duster can sprayed on the boards?

I know I am late to this problem, and I don't remember all that has been done, but these are my thoughts... if they are dupes, sorry.

 

These guys are giving me the shaft because of the stink I raised yesterday, I will probably obtain the car and fight this battle in court later. The service manager from the above post threatened me when he responded to my e-mail stating my issues with the treatment I had recieved, with 6-16 hours worth of labor $85 a hr just to determine the resistance of the replacement CCM I sent them. MY SERVICE REP TOLD ME IF YOU CAN FIND A PART THAT WILL WORK BY ALL MEANS BRING IT IN IT WILL HELP SPEED THIS UP INSTEAD OF WAITING UNTIL 4/06. These guys dont understand I am not just going to roll over.

 

I know your steaming and I would be too but you get more flies with honey than vinegar.Not many people have reported good experiences with dealers and you still took it there.Unless they sell lotsa Vettes they may be ignorant.Ignorance is curable stupidity is not.A firm but polite demeanor goes a long way toward getting what you want.Everyone wants a little respect.

 

I think it's gone way beyond that. As Bogus said CCM has nothing to do with the engine once it is running. The ECM can become heat soaked and cause issues, but not the CCM it's tucked comfy behind the radio head. Point is either the service manager is just giving him a bunch of BS or he hasn't a clue what he's talking about. Most likely a combination of each. But he obviously doesn't want his business at this point. Any further I think they're just sucking you for money and making you more angry.

Do you have ability to do some of your own work? If so, I'd get the vehicle back. It depends on your resources.

I think we've discussed this to some degree before. There are a couple area's you can look at that would cause this problem. Assuming it's as described; engine dies when it hits op temp or above but seems fine when its a cold start.

If they wanted to solve this it shouldn't have taken them more than about 4 hrs or so, especially that have the fancy tech 1 computers/analyzers rather than us weekend warriors reading codes and then analyzing the diagnostic procedures to isolate the cause(s).

Depending on what codes and what modules the DTC's appear and if the symptoms of what I presumed, I'd be looking at a couple items. The tach filter, coil and ignition coil module, and the ECM. If there are serial data link errors I'd also look at the connector on the ignition coil module.

Tom Piper knows the procedure to by-pass the tach filter to isolate it and I just can't remember how he said to do it.

Sometimes these problems come in groups, and you may need to isolate one at a time. Faulty tach filter can cause lots of issues such as wildly jumping tach reading, multiple new ign coil modules to not fire the ignition but still allow the old module to fire it. The coil/ignition coil module must have the proper heat sink grease applied to its plate before mounting to the engine. If not it cooks a coil module, and dielectric grease is not the proper product (ask me how I know). When I pulled mine which was probably the only time it's ever been pulled all the heat sink compound was gone from over time. If they had this module off and didn't put heat sink compound you can be asssured it doesn't take no time to cook an ign coil module.

But I think what your getting is a heat soak ECM or a failing connection to the ECM due to heat causing a bad connection.

It'd be real interesting to see what codes it's throwing when it dies.

 

I am leaning toward just getting the car back an checking ICM AND ECM FOR POSSIBLE ISSUES,My CCM is probably good and this has just been a ride from hell. I will see what dealer tells me early on tommorrow. Car starts and runs so that tells me the salvage CCM is doing its job.

 

I had a bad ignition module, it'd open up like clockwork when the engine heated up and kill spark. Wouldnt restart until letting motor cool for 1/2 hour at least.

Um, what's a CCM and what car are we talking about?

 

I believe the computer shuts off the fuel pump if it no longer sees reference pulses from the distributor.

 

Exactly. And that symptoms sounds exactly what I went through. Once I replaced the ECM it was fine. While swapping the PROM I noticed a strong scent of burned silicone or electrical components so I knew then it was a heat soak failing component.

By the way if one ever has to take the CCM out it does help to spend a little extra time to remove the radio head which also means the console and radio trim. But it gives you so much more leaverage with the unit and protecting its connectors which are on the bottom that you just can't get by just trying to remove it from the side. I doubt your CCM is causing any issues here. I think if you swap out the ECM your problems may be over.

 

Looks like you're getting more help here on the forum than at the dealership. From my experience of knowing personally many GM technicians, they would rather work on a bicycle that has been run over by a bulldozer than work on a customers Corvette, and it has absoutely nothing to do with the Corvette.

 

Well guys they called today and said come get it we cant fix it NO CHARGE, this is after 8-weeks of crap so they did get it to a running condition only when you shut it down after its operating temperture it wont Crank back up. hopefully I will be able drive it home and it not die. Another forum member 95BHAM is going to Gordons class this weekend so I will have it home may be we can do what the dealer could not.

 

CC - The CCM is the Central Control Module. It's kinda like the master brain. It also contains the VATS data that sends info to the ECM to allow it to start.

Once the engine is started, the CCM acts only as a traffic cop, guiding data from the ECM to the dash and to the EBCM - brake computer.

The CCM first appeared in 1990.

Kryptonite - CONGRATS!!!!!!!!!!!!! That's GREAT!!!!!!!!