Test Notes

Charging System Voltage:

Normal Operation
The air bag diagnostic monitor measures voltage at pins 11 (circuit 614, GY/O) and 12 (circuit 623, P/W). The voltage at these pins is controlled by two resistors inside the air bag diagnostic monitor and the voltage varies with charging system voltage (the expected voltages at pins 11 and 12 are shown in the chart). If the voltage at both of these pins exceeds 5 volts, the air bag diagnostic monitor will flash out code 22.

Possible Causes
High voltage at pins 11 and 12 can be caused by:

NOTE: The wiring harness leading to the rear air bag sensor and bracket carries higher voltage circuits that may short to circuits 614 and 623.

1. A short in wiring harness between circuits 614 (GY/O) or 623 (P/W) and another wire can cause high voltage on these circuits.
2. A short in the air bag sliding contact between circuit 614 and some of the horn or speed control wiring.

NOTE: The voltage on circuits 611 and 612 inside the rear air bag sensor and bracket is usually battery voltage or higher. There should be an open circuit across the contacts of the rear air bag sensor and bracket if the sensor is operating normally. If the sensor contacts are closed, the voltage on circuits 614 and 623 would be high (at least battery voltage).

3. A short across the normally open contacts of the rear air bag sensor and bracket.
4. Vehicle charging system voltage too high. If the alternator output voltage is too high (greater than 17 volts) it may cause a code 22 to occur.