Belt Tension Sensor Fault
Table of contents
B2909 MERCURY Possible Causes
- Faulty Belt Tension Sensor
- Belt Tension Sensor harness is open or shorted
- Belt Tension Sensor circuit poor electrical connection
- Faulty Restraints Control Module (RCM)
How do I fix code B2909 MERCURY?
Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins.
Cost of diagnosing the B2909 MERCURY code
The cost of diagnosing the B2909 MERCURY code is 1.0 hour of labor. The auto repair labor rates vary by location, your vehicle’s make and model, and even your engine type. Most auto repairs shops charge between $75 and $150 per hour.
Possible Symptoms
- Air Bag Warning Light ON
B2909 MERCURY Description
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 will report the failure to the Restraints Control Module (RCM). The RCM will store DTC B2909 in memory and flash either LFC 16 (or higher priority code if one exists) on 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 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 OCSM) must be installed as an assembly.