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.
Chart C-12A, Cooling Fan Circuit Diagnosis (1 Of 4) 3.8L: Notes
Power for fan motor goes through a 40-amp fusible link to terminal "A" of fan relays. Fan relays are energized when a good ground circuit is completed through the Powertrain Control Module (PCM) quad-driver. PCM energizes puller relay through terminal "GC4", when coolant temperature reaches 212°F (100°C) or when A/C is requested. PCM energizes pusher relay if A/C refrigerant pressure reaches 210 psi (99°C) or coolant temperature reaches 226°F (108°C).
- Using Tech 1 miscellaneous tests, low speed fan control will cause PCM to ground circuit No. 335. Puller fan should operate.
- Using Tech 1 miscellaneous tests, high speed fan allows control of circuit No. 473. Pusher fan should operate.
- When jumpering coolant temperature sensor wires together, scan tester should display coolant temperature of 304°F (151°C). Both fans will operate when ignition is cycled from off to on.
- Opening A/C pressure switch will cause pusher fan to operate.
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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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