bac22

I have a 96 LT-4 Coupe and I have a feeling my CCM is going bad from a damn mouse that got into the dash a few years back.

I understand you need to have them re-programmed, but didn't know if this was done by a dealer now a days or it needed to be sent off?

Otherwise I realize the mileage and key resistor value would change...prefer to keep my current mileage rather then though in a used CCM that didn't match up.

I've seen some used ones on ebay. I haven't dug into the problem too much, it's possible just some bad wires, just doing my homework ahead of time before I dig into it further this spring.

bac22

Hhhhmmmm...no one has replaced a BCM before?

WVZR-1

I've done maybe 3, but all when they were available through GM or ACD Cluster exchange. I keep a spare for my '90 but have only used it for some diagnostics after confirming the VIN, VATS and mileage in it. I've no idea if available through a dealer exchange anymore or not. I would ask. Programming (VIN & ODO) even though a '96 I believe requires a Tech1 or 1a with MASS STORAGE. I have a Tech1 and had no issues with ODO/VIN on what I've done.

I do believe there are 3d party repair facilities but I'd be reluctant. For diagnostics a used if purchased right might be an option. I don't believe there's any RPO/OPTION CONTENT in the Corvette BCM in '96 but I've not looked. I have a FSM for a '96 - I might check.

What specific issues? Mice don't generally devour aluminum components so I'd think if mice/rodent damage it would be wiring related between components.

bac22

One headlight grinds for about 10 seconds, thought it was worn gears, but still did it after I replaced the gears. Further trouble shooting using the FSM now indicates a BCM problem.

Other symptom is my voltage is jumping all over the place which just started from 13v to 15V while driving. Alternator seems to be okay, battery is a bit old, but I believe the BCM also helps to regulate voltage...although I haven't had a chance yet to fully troubleshoot this problem.

I agree it's probably wiring, but suspect the bastards shorted something that is now causing issues with my BCM. Already had to replace the PKE and RTD module in the car.

How hard is it to replace the BCM? Do you need to pull the dash apart?

WVZR-1

Everything you mention I'd think can't be linked "directly" to a CCM/BCM issue - my thoughts anyway. A '96 should have the same capability through the DIC to do nearly all diagnostics.

Do you have the FSM? If you do spend a couple hours in the 8D-1 through whatever and toggling, checking etc is covered quite well. It might take a couple reads but it's certainly a shortcut to your thoughts cincerning a potential CCM/BCM.

If you get no codes, it communicates with all controlled components and doesn't display ERR or --- in the LCD then I'd think certainly no reason to just do a CCM/BCM/

It's not fun to replace !!!!!!!!!!!!!!!!!

bac22

Thanks, I do have the FSM but haven't yet dug into them to resolve this issue and always find tribal corvette forum knowledge to be invaluable.

I guess my main question really was that if I had to get a used BCM, is the dealer able to reprogram for my mileage, vin, key or do I need to find another source?

Not sure what a Tech1 or 1a is but I would purchase that if need be...unless they are ridiculously expensive.

jmgtp

My 94 did the headlight grind for 10 seconds. The gears were fine, it was the plastic pins that needed replacing.

As for the voltage jumping around, the alternator has an internal voltage regulator that sounds like it may be failing. Have you verified the voltage spikes you are seeing on the dash with a digital multimeter on the alternator? If the meter reads the same spikes I'd suspect the alternator. If it doesn't, only then would I consider looking elsewhere. Even if you've had the alternator bench tested they can still do strange things when heat soaked.

A year or so ago I thought my alternator was failing. In fact it turned out that the + wire lug on the alternator had deteriorated. Just something to check.

WVZR-1

A USED CCM/BCM requires clearing of information "on the bench" - there's nothing that can be done using a Tech1, 1a or any other device to remove information OR reprogram a used!!

I doubt you need a BCM/CCM - sure doesn't sound like it. You've got the FSM and I believe you READ - not all years do the same and what Joe, John, Jim or Tom might pass on from their '90 or '92 or what ever isn't necessarily relevant for your '96.

bac22

If I switch connectors the grind goes to the other headlight while the original stops, I seem to recall reading in the FSM that it points to an issue with the BCM, but I do need to dig into a bit more.

Good tip, my car lives outside under a cover so waiting for winter to give up a little before jumping into this a bit more, but will be digging out my FSM's this weekend for some reading.

bac22

You're right, after digging into the FSM this weekend, my headlight problem is most likely related to a bad "Headlamp Door Actuator Control Module".

My initial info came from a prior question in which a forum member here told me the issue was with the CCM...just need to remember that while the wealth of info we all get from forum members is invaluable, once shouldn't always take it verbatim .

Also FSM doesn't use BCM, it's CCM which I corrected in my initial post.

Thanks for the help everyone, a bit of a relief that the issue might not be related to the CCM. At least the Headlight Control Module is easy to change out and my problem seems to be common with the C5 guys (same module).

As for my voltage problem will be checking grounds and alternator as that doesn't seem to be CCM related too.

Now if it will freaking warm up here in New England so I can get her ready for spring!!!!

jmgtp

Goodluck! We're expecting 12+" snow tomorrow in CT! That's ok, more time to wrench and I need it!