I recently bought a 91. Here is the problem. I have some CCM communication issues. I have a brand new in the box CCM but before I go to the dealer I thought I would see about "flashing" the one that is in there. The service manual says I am out of luck because the car has been driven for more than 100 miles. how should I proceed???

Thanks. (be kind to the new guy!)

 

Corvette Central can flash that CCM. I think the 91 and 94 are the same. Where did you get that brand new CCM? I had to buy a used one off ebay and have it flashed.

 

The guy I bought the car from had it. He said he had a hard time finding one but found it online from a dealer in Califoria a couple of years ago. I have talked to the local dealer (waste of time) and 2 speedo shops. No one seems to know 100% what is wrong.

 

New CCM's have to be programmed (flashed) by the dealer when they are installed. New CCM's allow for driving the car for up to 100 miles after installation. After that they cannot be flashed by the dealer as they lock themselves up. The flashing process also requires that the existing miles be known; with a fire, it sounds like there was no way to retrieve the actual miles at the time of the fire.

CCM's also hold information about certain options like FX3 and the C68 Climate Control System. Error codes for FX3 are stored there. IIRC, the CCM also handles ABS error codes. The CCM also holds the vehicle's VIN.

Flashing a replacement unused CCM should not be a problem for a dealer. Many cars have their odometer readings and other information stored in a CCM or similar box. But if the insurance company had the car repaired at some auto repair shop, there would be no way for them to do the flash. And the insurance company either didn't care to have a dealer do the work at extra cost or didn't understand what had to be done.

The Certificate of Title should show that the mileage is not correct at the time of sale. There's a place for odometer readings and typically some place to note the "odometer" has been replaced and mileage info is not known or correct.

 

Thanks C4Cruiser. you are confirming my suspisions. I have a GM approved specialty shop looking into it. I'll post their ideas when I hear from them on Monday. Untill I bought it, the car had not been driven much. But I did not have any trouble getting it on the road with the screwy dash.
Could it be anything else? The service advisor at the dealer said I needed a new cluster!

 

I am getting no where fast with this. I have been told to leave it becasue I could cause more trouble trying to fix it.

 

If a new (or reman) CCM was installed without flashing the miles that were stored in the old CCM, the odometer should have shown actual miles driven from the time it was installed. In effect, thjat would be from "0" to the number of miles driven since the CCM wa installed.

The fact that the trip odometer is working probably means the CCM is working as it should even though the trip odometer can be reset to 0 at any time. It also means that the speed sensor in the tranny is working.

It's possible that the odometer display itself is not working properly or that something does not have a good connection. The trip odometer is really a different "display" although it uses the same part of the dash display.

As far as flashing a new CCM, the old one doesn't need to be present. What is needed is a current mileage value that's either known to be right or a good guesstimate to enter into the new CCM, the vehicle VIN and whatever options are on the car that the CCM needs to know about. That can be taken off the RPO sticker.

I see no reason why a Chevy dealer cannot find out how to install or troubleshoot a CCM issue. They should have a service manual in house or they should be able to find diagnostic and repair information online through a secure GM tech database. All Chevy dealers have access to repair info for their cars.

Not sure what specific piece of tech equipment is used to "flash" a new CCM, but if the car has been driven more than 100 miles since the CCM was installed, the dealer will not be able to flash it in-house. Chances are a specialty shop won't be able to do it either.

A bad cluster, or at least the portion where the odometer display is is something else. And the chances are slim that a dealer would be able to come up with individual pieces or even a replacement cluster.

 

Thanks for that information George. I was particularly interested in the fact that the odometer should not be 0 but rather the mileage since the CCM was changed. Is there anyway to access the info directly from the CCM? That would tell me that the issue is either the cluster or the communication to the cluster. Does the CCM have to recognize the cluster I.E. does the cluster store the mileage or VIN and it needs to match the CCM? The cluster may or may not have been changed. In the sevice manual it states that the if the instrument cluster is removed or repaired and cannot register the same mileage as before it was removed, the replacement odometer must be set to 0.... and a label attached to the door frame. The instrument needed to programm the CCM is a tech 1 or CAMS. Thanks for your thoughts.

 

bottom line: If the dealer or other authorized service center CANNOT verify actual miles (had seen the car with the OLD ccm in and working and displaying actual miles) then they CANNOT program the replacement ccm with a guestimate mileage...thats illegal. The ccm that you have in there now cannot be reprogrammed after driving more than 100 miles by anyone without replacing internal programming (basically remanufacturing the entire unit).

 

it DOESNT have mileage stored, its NOT a communication issue, the ccm is now non programmable as stated earlier unless its rebuilt and a verification of actual mileage can be obtained. If it was communication , its would say "err"

 

but again, not to beat a dead horse but, it doesnt matter if you know about what the mileage SHOULD be, unless it can be documented..i.e. your working old ccm, then no reputable dealer will program a new ccm with stated mileage only, thats illegal. They CAN program it to work from zero and count mileage thereafter.

 

What is the name of the shop, CSI Miami?

 

So i just replaced the ccm in a flood damaged car,i know the actual mileage as it was on a dealers lot when flooded(katrinia)it has 94k and i need it programmed before i ruin the new ccm.Anyone have a tech 1 or know who can do this for me?Do they need to do it in car or?

any suggestions?

 

Quite a few guys on the forum have Tech 1's including myself, but the CCM does need to be in the car to program and you are far from close to me. Hopefully a member near you will respond and help you out.
If not my best suggestion would be to find an OLD Chevy dealer who might still have the tool. They now use entirely different tools and it is my understanding that the Tech 2 cannot program the CCM.

 

My buddy has a tech 2 with the obd1 adaptor,i am in east indiana,near indy/cincy/dayton.I would pay good to have this done-anyone local have one?

 

I could be wrong but I don't think the Tech 2 has the programming software for the CCM, at least that is what I've been told.
Since you own your own shop and a Vette, you may want to have your own tool. Here is a link,and others show up on Ebay fairly often.

http://cgi.ebay.com/ebaymotors/ws/eB...SS%3AUS%3A1123

Just noticed where you are located, try sending a PM to Johnnymo63, he is in Greenwood. If he does not have a Tech 1 he may know someone who does and if all else fails I would consider sending my tool to him.

 

Id really hate to fork out $400 or so on a tool ill just use once.If anyone has one they want to "rent me" ill gladly pay for it.If you need i can post pics of my shop/sign,give my phone number,ect-ill only need it for a day so you would have it right back,pm me if you want to help a guy out.

Ill pm him,thanks

 

Jim, you are correct. A Tech2 can not reprogram a C4 CCM.

The big issue here is he is still trying to get a guesstimate on mileage, which is completely unverifiable. Any dealership or shop is opening themselves up to a fraud charge with an oddometer rollback if they perform this service.

 

The title is actual w/94k,the oil change sticker says 94,451 so id say around 95-thats a heck of alot better than 0,I just want my car to work correctly,im not going to be selling it anyways,even if its a few hundred off its really not going to matter on value,1990 c4's arnt bringing enough money for tampering with anyways.Shame on those guys that do it!

 

Thanks for the clarification on the Tech 2. No argument from me concerning odometer tampering, doing so is a felony. I was taking the poster at his word that he could verify the mileage, but since the display is inoperative obviously that is subject to interpretation.
If he purchases his own Tech 1, he can handle this using his own discretion and any liability he might incur.
I hesitate to loan my tool to a new member who claims to run a speed shop and own his own C4 yet feels buying a Tech 1 would be a one use purchase............ I must be missing something.