Test Notes

Normal Operation
The air bag diagnostic monitor measures the resistance between pin 16 (circuit 613, DB/W) and pin 3 (diagnostic monitor reference ground). If the air bag diagnostic monitor measures a difference of more than 2.0 ohms between pin 16 and pin 3, it will flash out code 21 on the air bag indicator.

It is important to note that circuit 613 (DB/W) is riveted to the side of the rear air bag sensor and bracket case and the case of the rear air bag sensor and bracket is grounded to the vehicle. A good ground connection, at both the case and the vehicle body, is important to proper circuit operation.

Possible Causes
High resistance at pin 16 (circuit 613, DB/W) to ground can be caused by:

1. A poor connection due to loose mounting, dirt, or corrosion at the rear air bag sensor and bracket mounting surface.
2. An open or damaged wire in circuit 613 (DB/W) from pin 16 of the air bag diagnostic monitor connector to the rear air bag sensor and bracket.
3. An open wire or loose rivet inside the rear air bag sensor and bracket.