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Normal Operation

The Belt Tension Sensor (BTS) operates in conjunction with the Occupant Classification Sensor (OCS) system. The OCS system interprets a variable voltage signal provided by the BTS to identify the possible presence of a child safety seat in the front passenger seat. The voltage output of the BTS 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 Occupant Classification System Module (OCSM) monitors the pressure sensor, BTS and all circuitry for faults. If the OCSM detects a fault on any of the BTS circuits, it will store DTC B2909 in memory and send a message to the Restraints Control Module (RCM), which will store DTC B00A0:09 in memory and send a message to the Instrument Cluster (IC) 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 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 BTS. If a new OCS system, OCS system component or seat cushion foam pad are needed, a new OCS system service kit must be installed as an assembly.

FAULT TRIGGER CONDITION CHART

Fault PIDs(1) Description Fault Trigger Condition
2909___29___OD and 2909___29___CM Front Passenger Side Belt Tension Sensor Short to Ground When the OCSM senses a short to ground on the BTS circuits, a fault will be indicated.
2909___31___OD and 2909___31___CM Front Passenger Side Belt Tension Sensor Circuit Fault When the OCSM senses a failure on the BTS circuits, a fault will be indicated.
2909___30___OD and 2909___30___CM Front Passenger Side Belt Tension Sensor Circuit Open When the OCSM senses an open on the BTS circuits, a fault will be indicated.
2909___28___OD and 2909___28___CM Front Passenger Side Belt Tension Sensor Circuit Short to Battery When the OCSM senses a short to voltage on the BTS VREF or signal circuits, a fault will be indicated.
(1) 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 memory status and are associated with continuous DTC B2909.

This pinpoint test is intended to diagnose the following: 

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