J1850 GM Bench harness

This page documents a commercially-purchased bench flash harness for early GM vehicles. The original intended application was 99-02 F/Y body vehicles using the 12200411 PCM but it may work for others.

OBD2 port: 2: J1850 data (purple) 4: GND (black) 5: GND (black) 16: Unswitched +12V (orange)

ECU port: 19: Switched +12V (pink) 20: Unswitched +12V (orange) 59: J1850 data (purple) 60: GND (black)