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 MANUALSFORD1991RANGER 4WD V6-245 4.0LREPAIR AND DIAGNOSISTRANSMISSION AND DRIVETRAINTRANSFER CASECONTROL MODULETESTING AND INSPECTION
1991 Ford Ranger 4WD V6-245 4.0L
Control Module: Testing and Inspection
1991 Ford Ranger 4WD V6-245 4.0LSECTION Testing and Inspection
The electronic control module has a diagnostic capability of its internal circuitry. Self test procedure is as follows:
1. Disconnect five-wire and eight wire connectors from electronic control module.
2. Turn ignition switch to the RUN position.
3. Activate the self test switch and note result:
NOTE: The self test switch and indicator light is located on the Electronic Control Module.
A FLASHING INDICATOR LAMP, (approximately one flash per second), indicates control module is functioning properly.
A STEADY INDICATOR LIGHT, indicates that control module is inoperative and must be replaced.
1. Disconnect five-wire and eight wire connectors from electronic control module.
2. Turn ignition switch to the RUN position.
3. Activate the self test switch and note result:
Control Module Self Test:
NOTE: The self test switch and indicator light is located on the Electronic Control Module.
A FLASHING INDICATOR LAMP, (approximately one flash per second), indicates control module is functioning properly.
A STEADY INDICATOR LIGHT, indicates that control module is inoperative and must be replaced.
RENDER: 1.0x
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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.