GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Chevy C Cab/Chassis HD (GMT 400) 🢒 Brakes 🢒 Antilock Brake System 🢒 Seat Belt System Description and Operation

Seat Belt System

Caution: Restraint systems can be damaged in a collision. To help avoid injury and ensure that all parts in need of replacement are replaced:

   • Replace any seat belt system that was in use during the collision serious enough to deploy any automatic restraint device such as air bags and seat belt pretensioners. This not only includes seat belt systems in use by people of adult size, but seat belt systems used to secure child restraints, infant carriers and booster seats, including LATCH system and top tether anchorages.
   • Replace any seat belt system that has torn, worn, or damaged components. This not only includes adult seat belt systems, but built-in child restraints and LATCH system components, if any.
   • Replace any seat belt system if you observe the words "REPLACE" or "CAUTION", or if a yellow tag is visible. Do not replace a seat belt if only the child seat caution label is visible.
   • Replace any seat belt system if you are doubtful about its condition. This not only includes adult seat belt systems, but built-in child restraints, LATCH system components, and any restraint system used to secure infant carriers, child restraints, and booster seats.
Do NOT replace single seat belt system components in vehicles that have been in a collision as described above. Always replace the entire seat belt system with the buckle, guide and retractor assembly, which includes the latch and webbing material.

  1. The seat belt system includes a driver and\or passenger seat belt retractor and buckle.
  2. The driver's seat belt system, includes a seat belt switch in the driver seat belt buckle which sends a signal to the multifunction alarm module. When the driver seat belt is buckled, the driver's door is closed, and the ignition is ON, the following events will occur:
    3. • The multifunction alarm will not operate.
    • The fasten seat belt indicator will not operate.
  3. When the driver's seat belt is unbuckled, the driver's door is closed, and the ignition is ON, the following events will occur:
    4. •  The multifunction alarm will operate for 4 to 8 seconds and then go OFF.
    • The fasten seat belt indicator will operate for 20 seconds, until the driver seat belt is buckled.
    • The fasten seat belt indicator will flash for an additional 55 seconds before going OFF.
    • To diagnose a failure of the fasten seat belt indicator or audio alarm, refer to Symptoms - Seat Belts and Symptoms - Instrument Panel, Gages and Console in Instrument Panel, Gages and Console.

Seat Belt Indicator

The multifunction alarm module generates a fasten seat belt warning for 4 to 8 seconds and illuminates the fasten seat belt indicator when both of the following conditions occur:

    • The ignition is ON.
    • The driver seat belt is unbuckled.

When the ignition is ON, voltage is applied to the multifunction alarm module ignition 1 voltage input. With the driver seat belt unbuckled, ground is applied to the multifunction alarm module through the seat belt switch signal. The multifunction alarm module applies voltage to the instrument cluster to illuminate the fasten seat belt indicator. The fasten seat belt indicator remains ON for approximately 70 seconds or until the driver seat belt is buckled.

If the driver seat belt is buckled before the ignition is turned ON, the fasten seat belt indicator will not illuminate.