If you have suffered water damage to your BCM, you may decide to replace it with a used unit. If you do so, the odometer on the instrument cluster will post an inaccurate mileage and stop working. To resolve this you need to reprogram the 93C56 chip on the cluster control board to zero miles. Along with that, you need to program the BCM eeprom chip to the correct mileage for your vehicle.

Then, when you start the Hummer, the speedo will query the BCM for the mileage and the correct mileage will display on the Speedo odometer, and.. the odometer will start to function again.

After finding no comprehensive resource that illustrates how to do this without expensive equipment I did some digging to find out how and have produced a video that shows how to do it using the CH341A programmer (about $30) and TachoSoft odometer software (about $50). The link is attached. You will need to know how to solder, you should have access to a hot air station for removing the chip, need a computer or laptop with a USB port, and should have some mechanical skill.

 

Thank you. Good stuff.

 

I hope I never need this..... Thanks for sharing.

 

U r welcome