Principles of Operation

Driver Door Module (DDM)

Principles of Operation

NOTE: The Smart Junction Box (SJB) is also known as the Generic Electronic Module (GEM).

The Driver Door Module (DDM) allows the driver to program a personalized seat position that can be recalled using the memory set switch or a Remote Keyless Entry (RKE) transmitter (part of the Integrated Keyhead Transmitter (IKT) [Passive Anti-Theft System (PATS) only] key or part of the Intelligent Access (IA) [PATS with push button start] key). In addition to the position of the driver exterior mirror, the DDM also controls the position of the passenger exterior mirror and the adjustable pedals. The DDM is hardwired to the power mirror switch, driver exterior mirror, memory set switch and sends messages over the Medium Speed Controller Area Network (MS-CAN) to the Driver Seat Module (DSM) to adjust the passenger exterior mirror. Refer to Hydraulic System, Brakes &/or Brake Pedal Assy for information on the adjustable pedals. Refer to Mirrors for information on the exterior mirrors.

Field-Effect Transistor (FET) Protection

The SJB utilizes a Field-Effect Transistor (FET) 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 of the fault. The circuit then resets after a customer demand of the function (switching the component on, 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 cannot be cleared by a command to clear the continuous DTCs. The module does not allow this code to be cleared or the circuit restored to normal operation 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 clears and the circuit function returns.

Each circuit has 3 predefined levels of short circuit tolerance established in the module based on each circuits' capability. When the first or second level is reached, the continuous DTC associated with the circuit sets along with DTC B106E. These DTCs may be cleared using the Clear DTC operation on the scan tool as long as the fault itself has been corrected. If any of the circuits are shorted past the third level, then DTCs B106F and B1342 set along with the associated continuous DTC. This DTC cannot be cleared and the module must be replaced.