Normal Operation

When the ignition switch is turned to the START position, the Body Control Module (BCM) and PCM receive a request to start the engine. When the PCM receives the correct coded key ID messages from the BCM and the correct input from the Transmission Range (TR) sensor that the gear selector is in PARK or NEUTRAL, voltage and ground is supplied to the starter relay coil. When the starter relay is energized the relay contacts close. Voltage is then supplied from Battery Junction Box (BJB) fuse 13 (30A) to the starter relay contacts which supplies voltage to the starter solenoid. The starter solenoid is grounded at the starter motor. Energizing the starter solenoid engages the starter drive into the ring gear and closes the starter solenoid contacts allowing voltage directly from the battery to the starter motor to crank the engine. The PCM disengages the starter once an RPM threshold is reached, a set crank time is exceeded or the ignition is turned OFF.

This pinpoint test is intended to diagnose the following: 

• Battery
• Battery cables
• Wiring, terminals or connectors
• Fuse
• Ignition switch
• PCM
• Starter motor
• Starter relay
• TR sensor
• Passive Anti-Theft System (PATS)
• BCM