Normal Operation
When the ignition switch is turned to the START position, the PCM receives a starter motor request signal and signals from the digital Transmission Range (TR) sensor that the vehicle is in PARK or NEUTRAL and voltage from the Run/start relay. The PCM supplies voltage and ground to the BJB starter relay causing the coil to energize and the relay contacts to close. This allows voltage to be supplied from Battery Junction Box (BJB) fuse 89 (40A) to the relay contacts, which then flows to the starter solenoid. The solenoid is grounded at the starter motor. Energizing the starter solenoid engages the starter drive into the ring gear and closes the solenoid contacts allowing voltage directly from the battery to the starter motor to start the engine. The PCM will disengage the starter motor based on engine running (RPM threshold), a set crank time has been exceeded or the ignition switch has been turned to the OFF position.
This pinpoint test is intended to diagnose the following:
- Anti-theft system
- Battery
- Battery cables
- Wiring, terminals or connectors
- Ignition switch
- PCM
- Starter motor
- Starter motor relay
- Digital Transmission Range (TR) sensor