Odometer storage
Thread Starter
Drifting
Joined: Mar 2004
Posts: 1,504
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From: Byron Center MI
Odometer storage
I'm looking at a '94 for a friend. I'm being told the sellers has all the legal documentation for an odometer swap. They are telling me the cluster was replaced at 77,000 miles back in 2003 and the car now has 88,000 on it. They are saying that the odometer was set to 0 miles when the cluster was changed and is now reading 11,000 miles. This does not add up in my mind. I worked at a Chevy dealer back in the late '80s when they first came out with digital cluster and if memory serves me right there was a chip in the cluster that stored the mileage and was to be put in the new cluster. Please fix my memory if it is wrong. I'm thinking this is a car to stay away from.
TIA Tim
TIA Tim
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
The later C4's had the mileage stored in the BCM (body control module). The display on the digital dash is simply an LCD; the data comes from the BCM.
The only way to alter the odometer in these later cars is by swapping out the BCM for a remanufactured version or installing one from another car.
Reman BCM's have the odometer reading set at 0 miles. You need a GM Tech I or II Scan Tool to change the odometer value to what was stored in the old BCM. And you can only do that before the new BCM records 100 miles after the install. After that point, the BCM cannot be updated to reflect true mileage.
The BCM also includes the vehicle VIN (which must be entered into the new BCM) and certain information about some options. For example if the car has the FX3 Selective Ride Control, the BCM is used to store and display FX3 trouble codes.
Also, vehicle titles do not have to have an odometer reading recorded once the car reaches 10 years old. You can check his documentation, but the dash cluster itself really doesn't have anything to do with whether or not the mileage displayed is correct.
Any shop with a scan tool can view the BCM VIN so I would check to insure it matches the windshield VIN plate.
The only way to alter the odometer in these later cars is by swapping out the BCM for a remanufactured version or installing one from another car.
Reman BCM's have the odometer reading set at 0 miles. You need a GM Tech I or II Scan Tool to change the odometer value to what was stored in the old BCM. And you can only do that before the new BCM records 100 miles after the install. After that point, the BCM cannot be updated to reflect true mileage.
The BCM also includes the vehicle VIN (which must be entered into the new BCM) and certain information about some options. For example if the car has the FX3 Selective Ride Control, the BCM is used to store and display FX3 trouble codes.
Also, vehicle titles do not have to have an odometer reading recorded once the car reaches 10 years old. You can check his documentation, but the dash cluster itself really doesn't have anything to do with whether or not the mileage displayed is correct.
Any shop with a scan tool can view the BCM VIN so I would check to insure it matches the windshield VIN plate.
Last edited by c4cruiser; Aug 27, 2007 at 07:20 PM.
Melting Slicks
Joined: Apr 2000
Posts: 2,408
Likes: 3
From: Bel Air Md
The later C4's had the mileage stored in the BCM (body control module). The display on the digital dash is simply an LCD; the data comes from the BCM.
The only way to alter the odometer in these later cars is by swapping out the BCM for a remanufactured version or installing one from another car.
Reman BCM's have the odometer reading set at 0 miles. You need a GM Tech I or II Scan Tool to change the odometer value to what was stored in the old BCM. And you can only do that before the new BCM records 100 miles after the install. After that point, the BCM cannot be updated to reflect true mileage.
The BCM also includes the vehicle VIN (which must be entered into the new BCM) and certain information about some options. For example if the car has the FX3 Selective Ride Control, the BCM is used to store and display FX3 trouble codes.
Also, vehicle titles do not have to have an odometer reading recorded once the car reaches 10 years old. You can check his documentation, but the dash cluster itself really doesn't have anything to do with whether or not the mileage displayed is correct.
Any shop with a scan tool can view the BCM VIN so I would check to insure it matches the windshield VIN plate.
The only way to alter the odometer in these later cars is by swapping out the BCM for a remanufactured version or installing one from another car.
Reman BCM's have the odometer reading set at 0 miles. You need a GM Tech I or II Scan Tool to change the odometer value to what was stored in the old BCM. And you can only do that before the new BCM records 100 miles after the install. After that point, the BCM cannot be updated to reflect true mileage.
The BCM also includes the vehicle VIN (which must be entered into the new BCM) and certain information about some options. For example if the car has the FX3 Selective Ride Control, the BCM is used to store and display FX3 trouble codes.
Also, vehicle titles do not have to have an odometer reading recorded once the car reaches 10 years old. You can check his documentation, but the dash cluster itself really doesn't have anything to do with whether or not the mileage displayed is correct.
Any shop with a scan tool can view the BCM VIN so I would check to insure it matches the windshield VIN plate.
