Trailer Lamps

PRINCIPLES OF OPERATION

The trailer parking and reversing lamps share the vehicle lighting outputs controlled by the smart junction box (SJB). The SJB uses existing inputs to determine if voltage needs to be supplied to the individual trailer stop/turn lamps.

The SJB utilizes a protective circuit strategy for many of its outputs (for example, the headlamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault is detected. A continuous DTC is stored at that time for the fault. The circuit will then reset after an ignition cycle or customer demand of the function (switching the component on, 30-minute battery saver being energized). When an excessive circuit load occurs several times, the module shuts down the output until a repair procedure is carried out. At the same time, the continuous DTC that was stored on the first failure will not clear by a command to clear the continuous DTCs. The module will not allow this code to be cleared or the circuit restored to normal until a successful on-demand self-test proves that the fault has been repaired. After the on-demand self-test has successfully completed (no on-demand DTCs present), the continuous DTC will have been cleared and the circuit function will return.

The vehicle is supplied with wiring to support an aftermarket trailer brake control module.

The trailer tow battery charging is controlled by a relay. When the ignition switch is in the RUN or ACC position, the trailer tow battery charge relay is energized, which routes voltage to the trailer tow connector.