Diagnosis And Testing - Seat Belt Control Timer Module: Notes

The Seat Belt Control Timer Module (SCTM) is connected to the Body Control Module (BCM). Problems with the circuitry will be indicated by the seat belt warning indicator lamp.

When the G-Sensor is at rest, current flows to the solenoids holding them back. The seat belt is movable. When the sensor reacts to the force of impact, it stops current flow to the solenoids. The solenoids close in milliseconds, locking the seat belts.

The timer allows current to flow through the sensor and the solenoids for 30 minutes after the ignition is turned OFF. The 30 minute limit stops excessive battery drain while the engine is not running.

Connected to the Door Ajar switches, the timer closes the circuit when a door opens and holds for 30 minutes after the door closes with the ignition OFF. This is necessary so the seat belts can be managed after the ignition has been OFF for more than 30 minutes. Turning the key to the ACCESSORY, RUN or RUN/START position will also cause the timer to activate the solenoids.