B2909
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PINPOINT TEST 17: DTC B2909 - BELT TENSION SENSOR FAULT
Normal Operation
The belt tension sensor operates in conjunction with 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 OCSM monitors the pressure sensor and circuitry for faults. If the OCSM detects a fault on any of the belt tension sensor circuits, it will store DTC B2909 in memory and send a message to the restraints control module (RCM), which will store DTC B2290 in memory and send a message to the instrument cluster module to illuminate the air bag warning indicator.The OCS system components (seat wiring harness, seat cushion frame, 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, seat wiring harness and OCSM) must be installed as an assembly.
- Fault PIDs that end in OD indicate an on-demand status and are associated with on-demand DTC B2909. Fault PIDs that end in CM indicate continuous monitor status and are associated with continuous DTC B2909.
Possible Causes
- Wiring, terminals or connectors
- Belt tension sensor
- OCSM
Diagnostic Procedure
WARNING: Always wear eye protection when servicing a vehicle. Failure to follow this instruction may result in serious personal injury.
WARNING: Do not handle, move or change the original horizontal mounting position of the restraints control module (RCM) while the RCM is connected and the ignition switch is ON. Failure to follow this instruction may result in the accidental deployment of the safety canopy and cause serious personal injury or death.
WARNING: Never probe the electrical connectors on air bag, safety canopy or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.
WARNING: Never probe the electrical connectors on safety belt buckle/retractor pretensioners or adaptive load limiting retractors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners or adaptive load limiting retractors, which increases the risk of serious personal injury or death.
CAUTION: Use the correct probe adapter(s) when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: The supplemental restraint system (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.
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