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.
Circuit/System Description
The engine control module (ECM) sends a pulse width modulated (PWM) signal of 0-12 volts via the cooling fan clutch control circuit to the cooling fan relay. The ECM monitors the cooling fan clutch control circuit during vehicle operation. When the cooling fan clutch is commanded ON, the control circuit is at a low voltage. When the fan clutch is commanded OFF, the control circuit is near battery voltage. The ECM uses this PWM signal to control the position of the oil control solenoid valve, located inside the cooling fan clutch.
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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.