SJB Protective Circuit Strategy

The SJB utilizes a protective circuit strategy for many outputs (for example, the headlamp output circuit). Output loads (current levels) are monitored for excessive current (typically short circuits) and are shutdown (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 on the component). When an excessive circuit load recurs several times, the module shuts down the output until the fault condition has been repaired and a successful on-demand self-test has been carried out. At the same time, the continuous DTC that was stored on the first failure does not clear by a command to clear continuous DTCs. The module only allows this code to be cleared or the circuit restored to normal when a successful on-demand self-test proves the fault has been repaired. After the on-demand self-test has successfully completed (no on-demand codes present), the continuous code will have been cleared and the circuit function returns.