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.
Ignition Switch
The ignition switch powers certain functions in the engine control module (ECM) via fuses in the front integrated relay/fusebox and central electronic module (CEM). The ignition switch also supplies the engine control module (ECM) with signals such as:
- wake up" signal
- start signal.
wake up" signal
The ignition switch transmits a high signal to the engine control module (ECM) via the central electronic module (CEM) indicating that the ignition switch is in position I or II. The system prepares for start-up (for example by temporarily activating the fuel pump (FP) relay).
Start signal
The ignition switch transmits a high signal to the engine control module (ECM) when the ignition switch is in position III.
The engine control module (ECM) activates the starter motor relay. The relay in turn activates the starter motor.
The fuse in the front integrated relay/fusebox supplies current to the ignition switch.
The central electronic module (CEM) has diagnostics for the ignition switch.
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:
- • 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.
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