Repair Pontiac Mid-size 1974-1983 Repair Guide

Seat Belt/Starter Interlock System


The seat belt/starter interlock system was used on 1974 and some 1975 cars. This system prevents the car from being started until the front seat occupants are seated and have fastened their seat belts. If the proper sequence is not followed, the engine will not start. If, after the car is started, the seat belts are unfastened, a warning buzzer and light will be activated.

The shoulder harness and lap belt are permanently fastened together, so that they must both be worn. The shoulder harness uses an inertia-lock reel to allow freedom of movement under normal driving conditions.

In case of system failure, an override switch is located under the hood. This is a "one-start" switch and must be reset each time it is used.


Since the requirement for the interlock system was dropped, the system may be legally disabled. The seat belt warning light is still required.

  1. Disconnect the negative battery cable.
  3. Locate the interlock harness connector which is on or near the fuse block. The connector has orange, yellow, and green leads running to it.
  5. Cut and tape the green lead on the body harness side of the interlock connector.
  7. If the car is equipped with heavy-duty cooling and the low coolant warning system, cut the yellow wire behind the connector and tape the ends.
  9. If the car is not equipped with heavy-duty cooling and the low coolant warning system, disconnect the buzzer from the fuse panel and remove it.
  11. Connect the battery cable. Check the system operation by starting the car with seat belt unfastened.