Test Notes

WARNING: SERVICING A LAMP FAULT CODE 13 (DTC B1913) WILL USUALLY OCCUR AFTER SERVICING OF A LAMP FAULT CODE 12 (DTC B1867) HAS BEEN COMPLETED. UNDER NO CIRCUMSTANCES SUBSTITUTE ANOTHER FUSE VALUE FOR THE 10A BATTERY FUSE. ANY FUSE OTHER THAN 10A MAY CAUSE DISARMING FAILURE AND MAY RESULT IN DANGER TO THE OCCUPANTS OF THE VEHICLE. DO NOT ATTEMPT TO REPLACE THE 10A BATTERY FUSE UNLESS THE AIR BAG SYSTEM FIRST HAS BEEN DEACTIVATED (SEE DEACTIVATION PROCEDURE FOR DETAILS).






NORMAL OPERATION
The air bag diagnostic monitor measures the voltage at Pins C1-2, C1-3, C1-4 and C1-5 of the air bag diagnostic monitor connector. The voltage at these pins is set by the air bag diagnostic monitor and varies with charging system voltage (the expected voltages are shown in the following table). If the air bag diagnostic monitor detects low voltage on any of these pins, the air bag diagnostic monitor will store in memory DTC B1913 and flash lamp fault code 13 on the air bag indicator to indicate a possible short to ground on these circuits.

At the same time the air bag diagnostic monitor begins flashing lamp fault code 13, it attempts to disarm the air bag system to prevent inadvertent deployment of the air bag(s) by blowing the 4 (10A) battery fuse feeding air bag diagnostic monitor Pins C1-13 and C1-14. It attempts to blow the fuse by activating a solid state switch which shorts the battery feed at Pin C1-13, Circuit 937 (R/W) to sheet metal ground at the air bag diagnostic monitor's bracket.

The air bag diagnostic monitor will make up to three attempts to blow this fuse, spaced one minute apart. If the air bag diagnostic monitor has blown the fuse and thus removed battery positive voltage (B+) at Pin C1-14, a DTC B1867 will be stored.

If the air bag diagnostic monitor attempts to blow the 10A battery fuse three times and fails each time, a DTC B1924 will be stored. After the 10A fuse is blown or three attempts to blow it fail, the air bag diagnostic monitor will not attempt to disarm again until the DTC B1913 has been serviced and cleared by performing DTC B1913.

Should the short on Pins C1-2, C1-3, C1-4 and C1-5 be intermittent or repaired, the air bag diagnostic monitor will flash a lamp fault code 53 (or a higher priority DTC such as lamp fault code 12 if one exists) on the next ignition switch cycle.

POSSIBLE CAUSES

Low Voltage at Air Bag Diagnostic Monitor Pins C1-2, C1-3, C1-4 or C1-5 Can Be Caused By:

- A short to ground on Circuits 607 (LB/O), 614 (GY/O), 615 (GY/W), or 616 (PK/BK) causing the diagnostic voltage to drop.

- Resistance to ground on Circuits 617 (PK/O), 619 (PK/W), 624 (Y/W), 625 (Y/LG) or internal resistance to ground in either of the primary crash sensors may activate an air bag diagnostic monitor circuit which may cause the voltage to drop.

- An internal short to ground within the air bag sliding contact causing the driver side air bag circuit(s) to be shorted to ground.

- An internal short to ground within the driver side air bag module or passenger side air bag module.