Test D: LFC 21/DTC B1921-RCM Bracket Ground Resistance Hi

D1:

D2 - D3:

D4 - D5:

D6 - D7:

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 MODULE-RESTRAINTS CONTROL (RCM) FOR CORRECT TORQUE VALUES.

The Restraints Control Module (RCM) monitors the resistance between the ground connections at its housing and the reference ground at pin 21. If the RCM detects a resistance greater than 100 ohms, it will store a Diagnostic Trouble Code (DTC) B1921 in memory and flash a Lamp Fault Code (LFC) 21 (or higher priority code if DTC exists) on the air bag indicator.

Possible Causes
High resistance between the RCM housing ground and pin ground can be caused by:
^ incorrect seating of the RCM retaining bolts.
^ incorrect tightening torque of the RCM retaining bolts.
^ high resistance on RCM logic ground circuit 57 (BK).