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 blowing battery fuse 4 (10 A) feeding air bag diagnostic monitor C232-13 and C232-14. It attempts to blow fuse 4 (10 A) by activating an internal solid state switch which shorts the battery feed at C232-13 to sheet metal ground at the air bag diagnostic monitor bracket.

WARNING: Do not under any circumstances substitute another fuse value for the 10 A battery fuse 4. 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 4 unless the air bag system first has been deactivated.

The air bag diagnostic monitor will make up to three attempts to blow this fuse, spaced at one minute apart. If the air bag diagnostic monitor has blown the fuse and thus removed battery voltage at C232-14, a DTC B1867 will be stored. If the air bag diagnostic monitor attempts to blow fuse 4 (10 A) three times and fails each time, a DTC B1924 will be stored. After battery fuse 4 (10 A) is blown or three attempts to blow it fail, the air bag diagnostic monitor will not attempt to disarm again until DTC B1924 or B1913 has been repaired and cleared.

The air bag diagnostic monitor also performs several self-tests every time the ignition switch is turned to the RUN position. If any of these tests fail, the air bag diagnostic monitor will flash Lamp Fault Code (LFC) 24. If any of these conditions later resumes normal operation, the DTC B1924 will be stored in 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 the 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
System disarm failure or internal diagnostic failure can be caused by:
- An improper fuse value in the battery circuit feeding air bag diagnostic monitor C232-13 and C232-14.
- 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 C232-13, the 10 A battery fuse 4 terminal, or elsewhere in the battery feed circuit.
- A vehicle charging system concern preventing the air bag diagnostic monitor from drawing enough current to perform its disarm.
- An internal air bag diagnostic monitor failure of on-board diagnostic or system disarm.
- Resistance to ground in the normally open air bag sensor feed circuits 617 (PK/O), 619 (PK/W), 624 (Y/W), and 625 (Y/LG).