Test Notes

NORMAL OPERATION
When the air bag diagnostic monitor detects a Diagnostic Trouble Code (DTC) B1913 or B1914 failure, it attempts to disarm the air bag system to prevent inadvertent deployment of the air bag(s) by opening Fuse K (10 A) feeding air bag diagnostic monitor Pins C276-13 and C276-14. It attempts to open Fuse K (10 A) by activating an internal solid state switch which shorts the battery feed at Pin C276-13 to sheet metal ground at the air bag diagnostic monitor bracket.

WARNING: Under no circumstances should another fuse value be substituted for the 10 A fuse. 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 fuse unless the air bag system first has been deactivated.

The air bag diagnostic monitor will make up to three attempts to open this fuse, spaced at one minute apart. If the air bag diagnostic monitor has opened the fuse and thus removed battery voltage at Pin C276-14, a DTC B1867 will be stored. If the air bag diagnostic monitor attempts to open Fuse K (10 A) three times and fails each time, a DTC B1924 will be stored. After Fuse K (10 A) is opened or three attempts to open it fail, the air bag diagnostic monitor will not attempt to disarm again until DTC B1924 or B1913 has been serviced and cleared.

The air bag diagnostic monitor also performs several self tests every time the ignition switch is turned to RUN position. If any of these tests fail, the air bag diagnostic monitor will flash lamp fault code 24. If any of these conditions later resumes normal operation, the DTC B1924 will be stored in background memory.

The failure will either generate a DTC B1924 or B1342, depending on the cause of the failure. DTC B1342 is a special case DTC that will only be retrieved as a result of running on-demand self test from a tester. An intermittent B1342 cannot exist due to this fact. This DTC indicates that an internal microprocessor fault exists in the air bag diagnostic monitor. DTC B1924 covers the other internal air bag diagnostic monitor faults and is handled like any other DTC.

POSSIBLE CAUSES

WARNING: The fuse must be replaced with a 10 A fuse. under no circumstances substitute another fuse value for the 10 A fuse. 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 fuse unless the air bag system first has been deactivated.

System disarm failure or internal diagnostic failure can be caused by:
- an improper fuse value in the battery circuit feeding air bag diagnostic monitor Pins C276-13 and C276-14.
- excessive resistance or opens in the battery feed circuit due to corrosion, poor crimps, etc. The excess resistance could occur in the wiring at the air bag diagnostic monitor harness Pin C276-13, the 10 A fuse terminal or elsewhere in the battery feed circuit.
- a vehicle charging system concern could prevent the air bag diagnostic monitor from drawing enough current to perform its disarm.
- an internal air bag diagnostic monitor failure on on-board diagnostic or system disarm.
- resistance to ground in the normally open primary crash sensor feed Circuits 617 (PK/O), 619 (PK/W), 624 (Y/W) and 625 (Y/LG).