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Home >> Acura >> 1988 >> Legend Base, 4D Sedan, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Electronic Control System >> Testing >> Code 4, CRK/CYL Sensor
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Code 4, CRK/CYL Sensor

  1. Turn ignition off and disconnect alternator sense fuse in 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 engine off. Disconnect CRK/CYL sensor connector nearest the sensor. Measure resistance across Blue/Yellow and Blue/Green terminals at sensor. If reading is not 500-1000 ohms, replace sensor. If reading is within specification, proceed to next step.
  3. Check continuity between ground and sensor Blue/Yellow wire terminal. Check continuity between ground and sensor Blue/Green terminal. If continuity exists, sensor is shorted to ground. Replace sensor. If no continuity exists, proceed to next step.
  4. Reconnect sensor connector. Attach system checker harness to right side wire harness only, not to ECU. Check resistance between connector terminal B19 and B20. Resistance should be 500-1000 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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