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 60 (ENGINE CONTROLS - SYSTEM/COMPONENT TESTS - EEC-IV (3.0L))IGNITION SYSTEMPINPOINT TEST G: NO CODES-INTERMITTENT DIAGNOSIS
1991 Mercury Tracer Base, 4D Sedan, Automatic
Pinpoint Test G: No Codes-Intermittent Diagnosis
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Pinpoint Test G: No Codes-Intermittent Diagnosis
WARNING: This page is about a different car, the 1994 Mercury Topaz, 1994 Mercury Sable, 1994 Ford Tempo, and 1994 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
- Talk to vehicle operator to determine symptoms. Review vehicle service history, including previous repairs and components replaced. If engine starts, go to next step. If engine does not start, go to PINPOINT TEST A.
- Wiggle Test With engine at idle, wiggle wiring harness and pull wires at ignition component connectors. If engine stalls, service harness and connectors as necessary. Check ICM mounting bolts. Repeat QUICK TEST, and service any codes present. If engine does not stall or miss, go to next step.
- Engine Warm Up Start engine and put A/C blower on medium. Close hood and allow engine to idle for 15 minutes. If engine stops, go to step 7). If engine does not stop, go to next step.
- Hot Restart Check Turn ignition off. Wait 10 minutes and attempt to restart engine. If engine does not restart, go to PINPOINT TEST A. If engine does restart, go to next step.
- Perform Wiggle Test With Engine Hot With engine at idle, raise hood, and perform wiggle test on connectors of primary ignition components. If engine quits, service wiring harness or connector as necessary. If engine does not quit, go to next step.
- Road Test Road test vehicle. If engine quits, go to next step. If engine does not quit, no problem is indicated at this time. Test is complete.
- Wiggle wiring harness, pull wires at connectors, separate and reconnect connectors for ignition components. If engine starts, repair or replace wiring harness and/or connector(s) as necessary. If engine does not start, go to next step.
- Check Sensor Shield Turn ignition off. Spray light mist of water on wiring harness and connectors. Measure resistance between sensor shield (find exposed shield in sensor cable) and negative battery terminal. If resistance is less than 5 ohms, go to PINPOINT TEST A. If resistance is 5 ohms or more, service or repair shield ground circuit.
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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.