1991 Acura Legend Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Code 54: Crank/CYL Sensor

NOTE: For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section. For vacuum diagrams, see VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section.
  1. Turn ignition off. Remove ACG fuse in underdash fuse box for 10 seconds to reset ECU. Start engine, and jumper diagnostic connector. Observe CHECK ENGINE light. If light is not flashing, problem is intermittent. Check for poor and loose connections at CRANK/CYL sensor connector and connector C353 at right shock tower. Test drive, and check again.
  2. If CHECK ENGINE light is flashing Code 54, turn ignition off. Disconnect 8-pin CRANK/CYL sensor connector nearest sensor. Measure resistance across Green/White and Black/White terminals at sensor. See Figure . If reading is not 650-900 ohms, replace sensor. If reading is within specification, go to next step.
  3. Check continuity between ground and sensor Green/White wire terminal. Check continuity between ground and sensor Black/White terminal. If continuity exists, sensor is shorted to ground. Replace sensor. If no continuity exists, go to next step.
  4. Reconnect sensor connector. Attach ECU test harness to main wire harness side only. Measure resistance between harness terminals B13 and B14. See Figure . Resistance should be 650-900 ohms.
  5. If resistance is not within specification, repair open in Green/White and/or Black/White wire. If resistance is within specification, check continuity of harness terminal B13 to ground. If continuity is not present, substitute a known good ECU. If condition goes away, replace ECU.
  6. If continuity exists, repair short to ground in Black/White wire between harness terminal B13 and 8-pin CRANK/CYL sensor 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.

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