GMC specific DTC OBD2 code: P1639 5 Volt Reference 2 Circuit
GMC specific DTC OBD2 code: P1640 Driver 1-Input High Voltage
GMC specific DTC OBD2 code: P1641 FC Relay 1 Control Circuit
GMC specific DTC OBD2 code: P1642 FC Relay 2 And 3 Control Circuit
GMC specific DTC OBD2 code: P1643 Engine Speed Output Circuit
GMC specific DTC OBD2 code: P1644 TP Output Circuit
GMC specific DTC OBD2 code: P1652 Powertrain Induced Chassis Pitch Output Circuit
GMC specific DTC OBD2 code: P1653 Oil Level Lamp Control Circuit
GMC specific DTC OBD2 code: P1654 Service Throttle Soon Lamp Control Circuit
GMC specific DTC OBD2 code: P1655 EVAP Purge Solenoid Control Circuit