DTC B1007: Checksum Value Error: Description
WARNING: This page is about a different car, the 2002 GMC Savana, 2002 Chevrolet Chevy Express, 2001 GMC Savana, and 2001 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
Passlock(tm) module calculates a checksum for contents of EEPROM when voltage is first applied. This calculated checksum is compared with checksum value stored in EEPROM. A history DTC will clear after 100 consecutive ignition cycles occur without a fault. Use Scan Tool to clear history and current.