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 DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - SYSTEM/COMPONENT TESTS - 1.9LEDIS SYSTEMPINPOINT TEST H
1991 Mercury Tracer Base, 4D Sedan, Automatic
Pinpoint Test H
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Pinpoint Test H
- Talk To Owner To Determine Symptoms View vehicle service history, including number of previous repairs and components replaced. If engine starts, go to step 2. If engine does not start, go to PINPOINT TEST A, Step 1.
- WIGGLE Test With engine at idle, raise hood, wiggle wiring harness and pull wires at ignition component connectors. If engine stalls, service harness and connectors as necessary. Check DIS mounting bolts. Rerun Quick Test. If engine does not stall or miss, proceed to step 2.
- Temperature Check With engine at idle and A/C on, leave blower on at medium speed and close hood. Allow engine to run for 15 minutes. If engine stalls, go to step 9. If engine does not stall, go to step 4.
- Hot Soak Check With engine off, hood closed, hot soak for 10 minutes. If engine restarts, go to step 5 If engine does not restart, go to PINPOINT TEST A, Step 1.
- WIGGLE Test After Heat Soak With engine at idle, raise hood, perform wiggle test on connectors of primary ignition components. If engine quits, service harness or connector. Rerun Quick Test. If engine does not quit, go to step 6.
- Road Test Road test vehicle. If engine quits, go to step 7. If engine does not quit, test is complete.
- Road Test WIGGLE Test Simulation Raise hood, wiggle wiring harness, pull wires at connectors. If engine quits, service or repair harness or connector. Separate and reconnect connectors for ignition components. Rerun Quick Test. If engine does not miss or falter, go to step 8.
- Check Sensor Shield With key off, measure the resistance between crankshaft sensor shield (find exposed shield in sensor cable) and negative terminal of battery. If resistance is less than 5 ohms, go to PINPOINT TEST A, Step 1. If resistance is 5 ohms or more, service or repair shield ground circuit.
NOTE:
Pin No. 7 (IGN GND OR IGND) is connected internally to the bottom 2 mounting holes at the base plate. This is the ignition ground circuit.
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.