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Continuous Memory Code 18 Or 212 (IDM Missing)

  1. Ensure that SPARK OUTPUT CHECK has been performed. See IGNITION CHECKS in theF - BASIC TESTING article in the ENGINE PERFORMANCE Section. Turn ignition on.
  2. 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.
  3. Apply DI overlay on breakout box. Disconnect PCM. For CCD (Black module) equipped systems, go to step 6). For non-CCD (Gray module) equipped systems, set DVOM on DC scale. Disconnect ignition coil wiring harness connector. Turn ignition on.
  4. Measure voltage between J7 (B -) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If voltage is greater than 5.0 volts DC, repair IDM circuit short to power between PCM and IDM 22K resistor. If voltage is less than 5.0 volts DC, turn ignition off.
  5. Measure resistance between J7 (B -) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If resistance is less than 10,000 ohms, repair IDM circuit short to ground between PCM and IDM 22K resistor. If resistance is 10,000 ohms or more, measure resistance between J4 (COIL-) at breakout box and terminal No. 4 (IDM) at PCM wiring harness connector. If resistance is not 20,000-24,000 ohms, repair open or shorted IDM circuit.
  6. 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 voltage is greater than 1.0 volt AC, replace PCM. If voltage is not greater than 1.0 volt AC, turn ignition off.
  7. Disconnect diagnostic connector from ICM. Leave ICM wiring harness connector 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, repair short to power in IDM circuit between PCM and ICM wiring harness connector.
  8. If voltage is 0.5 volt or more, turn ignition off. Measure resistance between J7 (B-) and J23 (IDM). If resistance is less than 10,000 ohms, repair short to ground in IDM circuit between PCM and ICM wiring harness connector. If resistance is greater than 10,000 ohms, measure resistance between and J23 (IDM) and terminal No. 4 of PCM wiring harness connector. If resistance is 5 ohms or less, replace ICM. If resistance is greater than 5 ohms, repair open in IDM circuit between PCM and ICM wiring harness connector.
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