Diagnostic Aids
WARNING: This page is about a different car, the 2000 Pontiac Firebird, 2000 Chevrolet Corvette, and 2000 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
Most likely cause of DTC P1626 is loss of serial data communication from BCM. Check for loss of power to BCM. Check serial data circuit for open, short to ground or short to voltage.