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.
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HOMESERVICE MANUALSFORD2004EXPLORER 2WD V6-4.0L VIN EREPAIR AND DIAGNOSISWINDOWS AND GLASSWINDOWSTESTING AND INSPECTIONPINPOINT TESTSTEST M
2004 Ford Explorer 2WD V6-4.0L VIN E
Test M
2004 Ford Explorer 2WD V6-4.0L VIN ESECTION Test M
PINPOINT TEST M: THE DEFROST SYSTEM IS INOPERATIVE
Normal Operation
Under normal operation the heated backlight relay receives power from circuit 185 (BK) and central junction box fuse 10 (10A). When the rear window defrost switch is depressed on the temperature control module, a message is sent to the instrument cluster module (ICM) through the multiplex link system. Once the ICM receives the message to turn on the rear window defrost the ICM grounds circuit 1009 (OG/YE) to activate the heated backlight relay. Power is then sent to the rear window defrost grid through circuit 186 (BN/LB) from the heated backlight relay. The rear window defrost grid then receives ground through circuit 1205 (BK) to chassis ground.
Possible Causes
- Inoperative ICM.
- Inoperative temperature control module.
- Inoperative heated backlight relay.
- Multiplex communication error.
- Open in circuits 185 (BK), 186 (BN/LB), 1009 (OG/YE), or 1205 (BK).
Test M1-M2:
Test M2-M5:
Test M5-M7:
Normal Operation
Under normal operation the heated backlight relay receives power from circuit 185 (BK) and central junction box fuse 10 (10A). When the rear window defrost switch is depressed on the temperature control module, a message is sent to the instrument cluster module (ICM) through the multiplex link system. Once the ICM receives the message to turn on the rear window defrost the ICM grounds circuit 1009 (OG/YE) to activate the heated backlight relay. Power is then sent to the rear window defrost grid through circuit 186 (BN/LB) from the heated backlight relay. The rear window defrost grid then receives ground through circuit 1205 (BK) to chassis ground.
Possible Causes
- Inoperative ICM.
- Inoperative temperature control module.
- Inoperative heated backlight relay.
- Multiplex communication error.
- Open in circuits 185 (BK), 186 (BN/LB), 1009 (OG/YE), or 1205 (BK).
RENDER: 1.0x
NO RELATED
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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.