Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Starting System
The starting system consists of the:
- starter motor.
- starter switch, part of the ignition switch.
- transmission range (TR) sensor.
- starter motor relay.
- starter solenoid.
- starter drive.
The starter motor:
- is a permanent magnet, gear reduction, 12V DC motor.
- has an integral starter solenoid.
- has an overrunning clutch in the starter drive.
The starter drive:
- is operated by the starter solenoid.
- engages the flywheel to turn the engine.
- has an internal overrunning clutch to disengage the starter motor when the engine starts.
The starter solenoid:
- is an electromagnet.
- engages the starter drive to the flywheel.
- when energized, contacts close, connecting the battery to the starter motor and causing the starter motor to turn the starter drive.
- is kept in the energized condition by a hold-in winding until the starter switch is released.
The starter motor relay, located in the battery junction box (BJB):
- controls current to the starter solenoid.
- is engaged by the ignition switch.
When the ignition switch is turned to the START position, the starter motor is energized, connecting the battery to the starter solenoid. The starter solenoid moves the drive lever to engage the starter drive with the flywheel ring gear and connects the battery to the starter motor.
The TR sensor prevents starter motor engagement unless the transmission is in the NEUTRAL or PARK position. Refer to AUTOMATIC TRANSAXLE/TRANSMISSION - 4R70E/4R75E article or AUTOMATIC TRANSAXLE/TRANSMISSION - TORQSHIFT article.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.