Pinpoint Test 16: DTC B2909 - Belt Tension Sensor Fault
PINPOINT TEST 16: DTC B2909 - BELT TENSION SENSOR FAULTNormal Operation
The belt tension sensor operates in conjunction with the occupant classification sensor (OCS) system. The occupant classification system module (OCSM) 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 checks the belt tension sensor circuits for faults. If the OCSM detects one of the following faults on any of the belt tension sensor circuits, it reports the failure to the restraints control module (RCM). The RCM stores diagnostic trouble code (DTC) B2909 in memory and illuminates the air bag warning indicator.
The OCS system components (seat wiring harness, seat cushion frame, seat cushion foam pad, bladder with pressure sensor and OCSM) 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.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Belt tension sensor (BTS)
- OCS system
WARNING:
- Remove restraint system diagnostic tools from the vehicle prior to road testing. If tools are not removed, the supplemental restraint system (SRS) device may not deploy in a crash. Failure to follow this instruction may result in serious personal injury or death in a crash and possibly violate vehicle safety standards.
- 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 SRS must be fully operational and free of faults before releasing the vehicle to the customer.
- Supplemental restraint system (SRS) components should only be disconnected or reconnected when instructed to do so within a pinpoint test step. Failure to follow this instruction may result in incorrect diagnosis of the SRS.
- To identify between a production OCS system and an OCS system service kit, inspect the OCSM electrical connector.
A production OCS system allows the disconnect of the electrical connector from the OCSM.
An OCS system service kit has the OCSM electrical connector glued to the module. It cannot and should not be disconnected or altered.
- 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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