B1921

PINPOINT TEST 8: DTC B1921 - AIR BAG DIAGNOSTIC MONITOR CIRCUIT OPEN

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. See RESTRAINTS CONTROL MODULE (RCM), for correct torque values. Failure to follow these instructions may result in personal injury.

NOTE: A resistance difference as low as 10 Ohms can set the lamp fault code (LFC).

The RCM monitors the resistance between the ground connections at the mounting bracket and the reference ground at 0810-101 pin 16, circuit (B/LB). If the RCM detects a difference in resistance, it will store diagnostic trouble code (DTC) B1921 in memory and flash LFC 14 (or higher priority code if one exists) on the air bag indicator.

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

WARNING: Restraint system diagnostic tools are for service only. Tools must be removed prior to operating the vehicle over the road. Failure to remove restraint system diagnostic tools could result in injury and possible violation of vehicle safety standards.

WARNING: Do not handle, move or change the original horizontal mounting position of the RCM while the RCM is connected and the ignition switch is ON. Failure to follow these instructions may result in the inadvertent deployment of the safety canopy and risk of personal injury.

WARNING: Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.

WARNING: The safety belt pretensioner is a pyrotechnic device. Always wear safety glasses when repairing an air bag equipped vehicle and when handling a safety belt buckle pretensioner or safety belt retractor pretensioner. Never probe a pretensioner electrical connector. Doing so could result in pretensioner or air bag deployment and could result in personal injury.

WARNING: Never probe the electrical connector on a safety canopy module. Doing so can result in safety canopy deployment and could result In personal injury.

NOTE: After diagnosing or repairing a supplemental restraint system (SRS), the restraint system diagnostic tools must be removed before operating the vehicle over the road.

NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test.

NOTE: If a seat equipped with a SRS component is being serviced, the SRS must be depowered.

CAUTION: When installing a new RCM, always make sure the correct RCM is being installed. The RCM 40-pin connector is keyed differently for vehicles with safety canopies and side air bags than the 40-pin connector for vehicles without safety canopies and side air bags. Do not force the 40-pin connector onto the RCM. If the connector is forced onto the RCM, damage to the RCM and/or connector will occur.

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