Principles of Operation

PRINCIPLES OF OPERATION

Power Door Locks
The vehicle security module (VSM) controls the door locks, remote keyless entry (RKE) system, and the memory locking feature. The normal path of the actuators is to ground through the VSM. The door lock control switch locks and unlocks all doors by grounding the appropriate circuit to the VSM. The VSM then supplies power to the appropriate common actuator circuit to lock or unlock all the doors.

NOTE: For vehicles equipped with E-Guard Cargo Protection System(TM), the side and rear cargo doors will not unlock electronically or from the interior door lock rod.

The sliding door memory lock feature locks the sliding door in the event that a lock command was issued by the operator while the sliding door was open. Since the door lock actuators are located in the sliding door, power is supplied to the actuators through the contact plate. When the sliding door is opened, the circuit is also opened. If a lock command is issued through the RKE transmitter or door lock control switches and the sliding door is opened, the memory lock feature stores the command and issues the lock signal to the door lock actuators once the sliding door is closed.

Remote Keyless Entry (RKE)
The RKE transmitter sends a frequency that is received by the VSM internal antenna. Depending on the frequency received, the VSM locks all the doors or unlocks the driver door. If the unlock frequency is received again within 3 seconds of the first unlock, the VSM unlocks all the doors.

If the frequency received is for the PANIC button, the VSM cycles ground to the horn relay and voltage to the parking lamps. The parking lamps and the horn continue to cycle until the PANIC button is pressed again or the ignition switch is turned to the ON position. The operating range of the RKE transmitter may be affected by aftermarket systems, dealer installed options, high power devices, or TV/radio transmission towers.

Field-Effect Transistor (FET) Protection
The VSM utilizes a FET protective circuit strategy for only one of its outputs (horn). 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 a customer demand of the function (switching the component on). 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.

Each circuit has 3 predefined levels of short circuit tolerance established in the module based on each circuit's 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 B106F sets along with the associated continuous DTC. This DTC cannot be cleared and the module must be replaced.

The horn circuit 1 (DB) is the only FET protected circuit.