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 MANUALSMERCURY1991TRACER BASE, 4D SEDAN, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 3 (ENGINE CONTROLS - TESTS W/CODES - EEC)CIRCUIT TESTSCIRCUIT TEST STP - SWITCH TO POWERSWITCH PERFORMANCE CHECK
1991 Mercury Tracer Base, 4D Sedan, Automatic
Switch Performance Check
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Switch Performance Check
WARNING: This page is about a different car, the 1992 Mercury Tracer, 1992 Ford Probe, and 1992 Ford Escort. However, it is still accessible from the selected car via links, so may be relevant.
Switch must be checked in ON and OFF positions. Switch should function as follows:
- BOO Switch is closed when brake pedal is applied.
- FAN Switch is closed when coolant temperature switch is grounded.
- DEF Switch is closed when rear defroster is on.
- HLDT Switch is closed when headlights is on.
- VST Switch is closed when engine is cranking.
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.