Test Notes

Normal Operation
The air bag diagnostic monitor measures the voltage at C209-2, C209-3, C209-4 and C209-5 of the air bag diagnostic monitor connector. The voltage at these pins is set by the air bag diagnostic monitor and varies with the 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 the DIAGNOSTIC TROUBLE CODE (DTC) B1913 and flash Lamp Fault Code (LFC) 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 LFC 13, it attempts to disarm the air bag system to prevent inadvertent deployment of the air bag(s) by blowing the battery fuse 2 (10 A) feeding the air bag diagnostic monitor C209-13 and C209-14. It attempts to blow the fuse by activating a solid state switch which shorts the battery feed at C209-13, circuit 937 (R/W), to sheet metal ground at the air bag diagnostic monitor 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 10 A battery fuse and thus removed battery positive voltage (B+) at C209-14, DTC B1867 will be stored. Refer to Pinpoint Test A, Normal Operation for further information.
- if the air bag diagnostic monitor attempts to blow the 10 A battery fuse three times and fails each time, DTC B1924 will be stored. Refer to Pinpoint Test Q, Normal Operation for further information.
- After the 10 A battery fuse is blown or three attempts to blow it fail, the air bag diagnostic monitor will not attempt to disarm again until DTC B1913 has been repaired and cleared by performing Pinpoint Test B.
- Should the short on pins C209-2, C209-3, C209-4 and C209-5 be intermittent or repaired, the air bag diagnostic monitor will flash a LFC 53 (or a higher priority LFC such as LFC 12 if one exists) on the next ignition switch cycle.

Possible Causes

WARNING: Repair of Lamp Fault Code (LFC) 13 (DTC B1913) will usually occur after the repair of LFC 12 (DTC B1867) has been completed. Do not under any circumstances substitute another fuse value for the 10 A battery fuse 2. Any fuse other than 10 A may cause disarming failure and may result in danger to the occupants of the vehicle. Do not attempt to replace the 10 A battery fuse 2 unless the air bag system first has been deactivated.

Air Bag Diagnostic Monitor Typical Pin Voltages With System Connected and Engine Running:

Low voltage at air bag diagnostic monitor C209-2, C209-3, C209-4 or C209-5 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 air bag 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.