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.
Start (-2005)
The starter motor (6/25) is powered via the starter motor relay (2/35). The relay is controlled by the engine control module (ECM) (4/46). The start process is as follows:
- The ignition key is turned to start position (position III)
- A high signal from the ignition switch (3/1) is transmitted to the engine control module (ECM) and starter relay via the central electronic module (CEM) and integrated relay/fusebox in the engine compartment. The engine control module (ECM) interprets this high signal as a request to activate the starter motor.
- The engine control module (ECM) activates the starter motor solenoid by grounding the relay for the starter motor relay. The relay is powered by the ignition switch
- The relay closes the circuit between the starter motor solenoid and the fuse in the integrated relay/fusebox in the engine compartment, activating the starter motor
- The engine control module (ECM) activates the starter motor until the ignition key is released from the start position (position III).
The starter motor will not be activated if:
- the immobilizer function does not permit starting. The engine control module (ECM) receives a signal regarding whether the immobilizer is active or inactive from the central electronic module (CEM) via the control area network (CAN)
- the gear selector is not in position "P" or "N" (automatic transmissions). The engine control module (ECM) receives a signal indicating the position of the gear selector from the transmission control module (TCM) (4/28) via both the controller area network (CAN) and from a directly connected cable between the engine control module (ECM) and transmission control module (TCM).
- the clutch pedal is released (manual transmissions, certain markets). The engine control module (ECM) receives a signal indicating the position of the clutch pedal from the central electronic module (CEM) via the controller area network (CAN).
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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