DTC 21: Safing Sensor Not Mounted to Vehicle Properly

Electrical Schematic:

Normal Operation
Circuit 940 ("GN") is riveted to the side of the safing sensor housing and the housing is grounded to the vehicle. A resistor inside the diagnostic monitor is connected to pin 16 (circuit 940 "GN") and a 5 volt reference voltage. If circuit 940 is properly grounded, the voltage at pin 16 will be 0 volts. If the voltage on circuit 940 is greater than 0.7 volts, the diagnostic monitor may flash a code 21, indicating that the safing sensor is not grounded properly to the vehicle.

If the voltage at both of these pins exceed 5 volts, the diagnostic monitor will flash a code 22.

Possible Causes
High voltage at pin 16 can be caused by:
1. A poor connection due to loose mounting, dirt, or corrosion at the safing sensor mounting surface.
2. An open or damaged wire in circuit 940 ("GN") from pin 16 of the diagnostic monitor connector to the safing sensor.
3. An open wire or loose rivet inside the safing sensor.

Pinpoint Test Steps:

21-1 - 21-4: