B2909

PINPOINT TEST 21: DTC B2909 - BELT TENSION SENSOR FAULT

Normal Operation

NOTE: Lamp fault code (LFC) 16 is shared between DTC B2290 and DTC B2909.

The belt tension sensor is part of the occupant classification sensor (OCS) system. The OCS system interprets a variable voltage signal provided by the safety belt tension sensor to identify, the possible presence of a child safety seat in the front passenger seat. The voltage output of the belt tension sensor is proportional to the amount of tension applied to the sensor by the belt, no tension low voltage (approximately 0.95 volt), high tension high voltage (approximately 3.8 volts).

The OCS system checks the belt tension sensor circuits for faults. If the OCS detects one of the following faults on any of the belt tension sensor circuits, it will report the failure to the RCM. The RCM will store diagnostic trouble code (DTC) B2909 in memory and flash either LFC 16 (or higher priority code if one exists) on the air bag indicator.

The OCS system components (seat cushion foam pad, bladder with pressure sensor and electronic control unit) are calibrated to each other and are serviced as an assembly. The OCS system components are not to be installed separately with the exception of the belt tension sensor. If a new OCS system, OCS system component or seat cushion foam pad are needed, a new OCS system service kit (seat cushion foam pad, bladder with pressure sensor and electronic control unit) must be installed as an assembly.

Possible Causes
- damaged wiring, terminals or connectors.
- a faulted belt tension sensor.
- a faulted OCS ECU.

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.

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough Inspection and Verification before proceeding with the Pinpoint Test.

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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