Test H: DTC B1921 - Air Bag Diagnostic Monitor Ground Circuit Open

PINPOINT TEST H: B1921 - AIR BAG DIAGNOSTIC MONITOR GROUND CIRCUIT OPEN

H1-H4:

H4-H7:

Lamp Fault Codes (LFCs)







The lamp fault code (LFC) indicate the specific fault associated with diagnostic trouble code (DTC) B1921:

WARNING: The tightening torque of the restraints control module (RCM) retaining bolts is critical for correct air bag supplemental restraint system (SRS) operation. Refer to Restraints Control Module (RCM) for correct torque values.

NOTE: A resistance difference as low as 10 ohms may set the LFC.

Normal Operation
The restraints control module (RCM) monitors the resistance between the ground connections at the mounting bracket and the reference ground at C310a pin 16, circuit 676 (PK/OG).

If the RCM detects a difference in resistance, it will store DTC B1921 in memory and flash LFC 1-4 on the air bag indicator.

Possible Causes
A resistance difference between the RCM bracket ground and harness ground can be caused by:
- wiring, terminals or connectors.
- RCM bracket not securely mounted.
- a faulted RCM.