Seat Belt Systems: Description and Operation

CIRCUIT OPERATION
The passive restraint seat belt system is used on vehicle built for the U.S. market. It consists of a passive restraint relay, left and right door latch switches, and solenoids located in the vehicle doors.

When the operator opens the door, the door latch switch is momentarily grounded and the passive restraint relay is energized. This sends voltage to all the solenoids in the doors allowing the seat belts to move without locking.

Logic internal to the relay control the amount of time the solenoids remain energized.

Power for the passive restraint relay logic and contact side of the relay is supplied on circuit M1. This circuit is protected by a 20 Amp fuse located in cavity 15 of the fuse block and HOT at all times.

Power for the fuse is supplied on circuit A6. This circuit is protected by a fusible link located near the auxiliary jumper post on the left toe box.

When the contacts in the relay CLOSE, circuits M1 and M10 are connected. Circuit M10 connects from the relay to the solenoids located in the doors.

Grounding for the solenoids and the input on door position to the passive restraint relay is accomplished on circuits R2 and R3. Circuit R3 connects from the relay to the left door solenoids and door latch.

Circuit R2 connects from the right door latch switch and solenoids to the right door to body connector. At the right door to body connector circuit R2 switches to circuit R3 and connects to the passive restraint relay.

Ground for the door latch switches is supplied on circuit Z1.