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Home >> Lincoln >> 2010 >> MKZ AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1014 (Supplemental Inflatable Restraint System) >> Diagnostic Tests >> Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) >> Pinpoint Test - Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS) >> Pinpoint Test Q: DTC B2909 - Belt Tension Sensor Fault >> Normal Operation

Normal Operation

WARNING: This page is about a different car, the 2008 Mercury Mariner and 2008 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

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 occupant classification system module (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 (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 occupant classification system module [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.

Fault PIDsa Description Fault Trigger Condition
2909_29_OD and 2909_29_CM Front Passenger Side Belt Tension Sensor Short to Ground When the occupant classification system module (OCSM) senses a short to ground on the belt tension sensor 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 belt tension sensor 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 belt tension sensor 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 either of the belt tension sensor circuits, a fault will be indicated.

a 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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