Vehicles With Key Transponder Module (KTM)
Key transponder module is part of engine immobilizer system. An engine immobilizing device is located in the plastic head of the ignition key. Engine immobilization occurs automatically when the ignition key is turned to (0) position.
Engine cranking is controlled by ignition switch, Engine Control Module (ECM), Body Processor Module (BPM), Key Transponder Module (KTM), ignition key transponder exciter, ignition key transponder, park/neutral switch, and not-in-park switch at gear selector. See Fig 1. The KTM receives signal from ignition switch as key is turned to ON position (II). The KTM energizes reader/exciter and key transponder broadcasts security code.
If code matches the KTM code, the KTM outputs an okay to start signal to ECM. The ECM enables fuel and ignition. The ECM outputs security signal to BCM. The BCM receives park signal from not-in-park switch at gear selector and enables cranking if security system has been disarmed. With ignition switch in START position (III), crank signal is received by BCM. The BCM grounds starter relay coil to energize starter. The ECM receives starter relay coil signal and sets engine starting values.