Tests AR: LFC 21/DTC B1921 - RCM Bracket Ground Resistance High

Pinpoint Test AR1:

Pinpoint Test AR2:

Pinpoint Test AR3-AR4:

Pinpoint Test AR5-AR6:

Pinpoint Test AR7:

Pinpoint Test AR: LFC 21/DTC B1921 - RCM Bracket Ground Resistance High

Normal 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 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 1203 (BK/LB).
- an RCM internal concern.