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Home >> Honda >> 1987 >> Prelude Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> PGM-FI Electronic Control System >> Testing >> Code 4, TDC/Crank Sensor
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Code 4, TDC/Crank Sensor

  1. Turn ignition off. Remove clock fuse in the under-hood relay box for 10 seconds to reset ECU. Start engine and observe PGM-FI warning light. If light is off, problem is intermittent. Test drive and check again.
  2. If light is on, turn ignition off. Disconnect TDC/CRANK sensor connector nearest the sensor. Measure resistance across terminals "C" and "D" at sensor. If reading is not 700-1000 ohms, replace distributor assembly. If reading is within specification, proceed to next step.
  3. Check continuity between ground and sensor terminals "C" and "D". If continuity exists, sensor is shorted to ground. Replace distributor assembly. If no continuity exists, proceed to next step.
  4. Reconnect sensor connector. Attach system checker harness to main harness only, not to ECU. Check resistance between connector terminals B10 and B12. Resistance should be 700-1000 ohms.
  5. If resistance is not within specification, repair open in Blue/Yellow and/or Blue/Green wire. If resistance is within specification, substitute a known good ECU. If condition is rectified, replace original ECU.
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