Circuit Operation

Resistor sensing contacts are located in the ignition key lock cylinder. These contacts read the resistor pellet value on the key and compare it with the value stored in the PASS-Key II module. If the resistor pellet has the wrong value, the module shuts down the Powertrain Control Module (PCM), de-energizes the starter enable relay, and turns the SECURITY indicator on. This is done by removing the ground from terminal A4 and the signal from terminal A3. This prevents the vehicle from starting for 3 minutes even if a key with the right resistance is inserted in the ignition switch. After the SECURITY indicator goes out and the module timer is reset, a key with the right resistance value can be used to start the engine.

If the ignition key lock cylinder contacts or wiring are faulty, or a defective key (invalid resistance value) is used to try to start the vehicle, the SECURITY indicator flashes and the vehicle does not start. This does not shut down the PCM or starter enable relay. If this condition develops while the engine is running, the SECURITY indicator lights and the PASS-Key II module is inactive (vehicle starts) until the fault is repaired. After clearing a fault, the SECURITY indicator will stay on for approximately 60 seconds.

If the PASS-Key II module must be replaced, the new module automatically programs itself to the resistance of the key used for its first ignition cycle. Using the interrogator will program the module to the value it is set at. A 5 second SECURITY lamp illumination indicates the new module has been programmed. If a defective key is used for the first cycle after replacement, the SECURITY lamp flashes, indicating that the module did not program itself. Once programmed, the module is not reprogrammable.