DTC 21: Safing Sensor Not Mounted to Vehicle Properly

Electrical Schematic:

Normal Operation
Circuit 951 ("GN/Y") is riveted to the side of the center cowl safing rear air bag sensor housing and the housing is grounded to the vehicle. A resistor inside the air bag diagnostic monitor is connected to Pin 16 (circuit 941 "R/GN") and a 5 volt reference voltage. If circuit 951 is properly grounded, the voltage at Pin 16 will be 0 volts. If the voltage on circuit 941 is greater than 0.7 volts, the air bag diagnostic monitor may flash a code 21, indicating that the center cowl safing rear air bag sensor is not grounded properly to the vehicle.

Possible Causes
High voltage at Pin 16 can be caused by:
1. A poor connection due to loose mounting, dirt, or corrosion at the center cowl safing rear air bag sensor mounting surface.
2. An open or damaged wire in circuit 941 ("R/GN") or 951 ("GN/Y") from Pin 16 of the air bag diagnostic monitor connector to the center cowl safing rear air bag sensor.
3. An open wire or loose rivet inside the center cowl safing rear air bag sensor.

Pinpoint Test Steps:

21-1 - 21-4: