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 B: CONTINUOUS MEMORY CODE 212
1991 Mercury Tracer Base, 4D Sedan, Automatic
Pinpoint Test B: Continuous Memory Code 212
1991 Mercury Tracer Base, 4D Sedan, AutomaticSECTION Pinpoint Test B: Continuous Memory Code 212
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.
- Connect Test Equipment Turn ignition off. Connect DI Diagnostic Cable (007-00097) to EEC-IV Breakout Box (T83L-50-EECIV), negative battery terminal and ICM. See Figure . Leave B+ lead disconnected. Ensure PIP OPEN/NORMAL/SPOUT OPEN switch is in NORMAL position. Use DI overlay on breakout box. Disconnect PCM and go to next step.
- Check IDM Signal At PCM Turn ignition off. Set DVOM on AC scale. Crank engine while measuring voltage between J7 (B -) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If AC voltage is more than 1.0 volt, replace PCM. If AC voltage is 1.0 volt or less, go to next step.
- Check For Short To Power In IDM Turn ignition off. Disconnect diagnostic connector from ICM. Leave ICM wiring harness connected to diagnostic cable. Set DVOM on DC scale. Turn ignition on. Measure voltage between J7 (B -) and J23 (IDM). If voltage is less than 0.5 volt, go to next step. If voltage is 0.5 volt or more, repair short to power in IDM circuit between PCM and ICM wiring harness connector.
- Check For Short To Ground In IDM Turn ignition off. Measure resistance between J7 (B -) and J23 (IDM). If resistance is 10,000 ohms or less, repair short to ground in IDM circuit between PCM and ICM wiring harness connector. If resistance is more than 10,000 ohms, go to next step.
- Check For Open IDM Measure resistance between and J23 (IDM) and terminal No. 4 of PCM wiring harness connector. If resistance is less than 5 ohms, replace ICM. If resistance is 5 ohms or more, repair open in IDM circuit between PCM and ICM wiring harness connector.
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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.