Test F: LFC 14/DTC B1921 - Air Bag Diagnostic Monitor Circuit Open

F1:

F1 - F2:

F2 - F3:

F4 - F5:

F5 - F6:

Normal Operation

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 AIR BAG CONTROL MODULE FOR CORRECT TORQUE VALUES.

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

The restraints control module (RCM) monitors the resistance between the ground connections at the mounting bolts and the reference ground at C310a pin 16, circuit 1203 (BK/LB). If the RCM detects a difference in resistance, it will store Diagnostic Trouble Code (DTC) B1921 in memory and flash Lamp Fault Code (LFC) 14 (or higher priority code if one exists) on the air bag indicator.

Possible Causes
A resistance difference between the RCM mounting bolts ground and harness ground can be caused by:
^ Wiring, terminals, or connectors.
^ RCM not securely mounted.
^ RCM is faulted.