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.
Engine Start-Up Mode
This is an Open Loop mode. The following actions occur when the starter motor is engaged.
The PCM receives inputs from:
- Direct Battery voltage
- Accelerator Pedal Position Sensor (APPS)
- Engine Coolant Temperature (ECT) sensor
- Crankshaft Position (CKP) sensor
- Intake Manifold Air Temperature (IMAT) sensor
- Manifold absolute pressure (MAP) sensor
- Throttle position sensors (TPS)
- Camshaft Position Sensor (CPS) signal
The PCM monitors the crankshaft position sensor. If the PCM does not receive a crankshaft position sensor signal within approximately 3 seconds of cranking the engine, it will shut down the fuel injection system.
The fuel pump is activated by the PCM through the fuel pump relay located in the front Power Distribution Center (PDC).
Voltage is applied to the fuel injectors with the ASD relay via the PCM. The PCM will then control the injection sequence and injector pulse width by actuating ground circuit to each individual injector on and off.
The PCM determines the proper ignition timing according to input received from the crankshaft position sensor.
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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