Body Control Systems: Description and Operation
MODULE CONTROLLED FUNCTIONSIf the vehicle is equipped with autolamps or the remote keyless entry (RKE) system (or both), it will be equipped with one multifunction electronic module: the vehicle security module.
Vehicle Security Module
The vehicle security module monitors the inputs and provides outputs and diagnostic information for the following systems:
- Autolamps
- RKE system
The vehicle security module also provides the instrument cluster with door ajar information over the universal asynchronous receiver-transmitter (UART) based protocol (UBP) communications network in order for the instrument cluster to close the interior lamps relay, providing power to the interior lamps and the running board lamps (if equipped). If the vehicle is not equipped with a vehicle security module, the door ajar switches are hardwired to the instrument cluster. If equipped, the vehicle security module grounds the horn relay when the panic function is commanded by using the RKE transmitter.
Upfitter System
The vehicle is also equipped with an upfitter system to allow aftermarket components to be added to the vehicle without adding unnecessary, extra circuitry.
The upfitter system consists of:
- Four upfitter relays
- Upfitter relay box
- Upfitter switch assembly
- Four blunt cut relay controlled voltage circuits
The 4 upfitter system switches are low current on/off latch switches that control 2-10A and 2-30A, fused, voltage at all times, relays. The upfitter switches are not designed to carry any significant loads. They are designed to allow the driver to manually close the relay coil circuit. When the relay coil circuit is completed the relay contacts close and provide voltage to added options. The upfitter relays are located above the glove box. The relay and relay contacts are designed to carry the actual load that is being added to the vehicle. The output circuits of the upfitter relays go to the interior of the vehicle and are blunt cut. The blunt cut ends are located behind the central junction box (CJB) and are accessed through the opening in the instrument panel when the instrument panel steering column cover is removed. The upfitter switches are located in the instrument panel center finish panel under the climate control assembly. The upfitter switches have individually lighted indicators that illuminate when the switch is in the on position. The indicator lights for the individual upfitter switches are not controlled by the headlamp switch. The upfitter switch backlighting is adjustable and is controlled by the headlamp switch.