Principles of Operation

The SJB is a multifunction control module that controls many of the vehicle systems. Several SJB functions utilize hardwired inputs and/or outputs. The SJB controls the following hardwired functions, using the corresponding inputs and outputs:

In addition, the SJB is involved in other vehicle systems through communication over the controller area network (CAN). For a detailed list of SJB network inputs and outputs, refer to MODULE CONFIGURATION article.

Some SJB parameters are programmable. Two types of programmable parameters are available: vehicle configuration and customer preference. Refer to MODULE CONFIGURATION article for additional information on programmable parameters.

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 service procedure is performed. 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.

DTC B106E sets when the SJB has disabled a circuit due to a repetitive fault causing a circuit overload. A corresponding DTC for the circuit in question will also be set as follows:

• DTC B1034 - Audio unit start circuit short to B+
• DTC B1218 - Horn relay circuit short to B+
• DTC B1304 - Accessory delay relay circuit short to B+
• DTC B1316 - Battery saver relay coil circuit short to B+
• DTC B1349 - Rear window defroster relay circuit short to B+
• DTC B1474 - Battery saver power relay circuit short to B+
• DTC B1502 - Left turn signal lamp output circuit short to ground
• DTC B1506 - Right turn signal lamp output circuit short to ground
• DTC B1626 - Keyless entry keypad output circuit short to B+
• DTC B2070 - Trailer tow relay circuit short to ground
• DTC B2501 - Left headlamp low beam circuit short to B+ or ground
• DTC B2503 - Right headlamp low beam circuit short to B+ or ground
• DTC B2505 - Left headlamp high beam circuit short to B+ or ground
• DTC B2507 - Right headlamp high beam circuit short to B+ or ground
• DTC B2512 - Fog lamp relay circuit short to B+
• DTC C1788 - Stoplamp relay output circuit short to ground
• DTC C1961 - Park lamp relay circuit short to ground
• DTC P0930 - Gear shift lock solenoid circuit short to ground