D: LFC 21/DTC B1921 - RCM Bracket Ground Resistance High
Normal OperationWARNING: The tightening torque of the Restraints Control Module (RCM) retaining bolts is critical for proper air bag Supplemental Restraint System (SRS) operation.
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 one exists) on the air bag indicator.
Possible Causes
High resistance between the RCM housing ground and pin ground could 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 649 (BK/OG).
- RCM internal concern.
Pinpoint Test Steps:
D1:
D2-D3:
D4-D5:
D6-D7:
