DTC B2502, Park Relay (BTSI) Shorted To Ground: Notes
WARNING: This page is about a different car, the 1997 Cadillac Seville, 1997 Cadillac Eldorado, and 1997 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
When transaxle is in Park, PZM controls park relay output low to enable Brake Transaxle Shift Interlock (BTSI). PZM will continuously monitor this voltage. DTC B2502 will set when park relay output is not active, IGN-1 input exists, and PZM determines output is low for 2 consecutive monitoring cycles. DTC B2502 will clear when park relay output is not active, IGN-1 input exists, and PZM determines output is high for one monitoring cycle.