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Home >> Honda >> 1989 >> Prelude S, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Tests W/Codes - Fuel Injected >> Testing - Trouble Code Tests >> Code 6: Coolant Temp Sensor

Code 6: Coolant Temp Sensor

  1. Turn ignition off. Remove clock fuse in the under-hood relay box for 10 seconds to reset ECU. Start engine and observe "CHECK ENGINE" light. If light is off, problem is intermittent. Test drive and check again.
  2. If light is on, warm engine to normal operating temperature (cooling fan comes on). Disconnect 2-wire coolant sensor connector. Measure resistance across sensor terminals.
  3. If resistance is not 200-400 ohms, replace TW sensor. If resistance is within specification, turn ignition switch on. Measure voltage between ground and Yellow/Green wire sensor harness. If reading is about 5 volts, go to step 4). If reading is not about 5 volts, go to step 5).
  4. Measure voltage between Yellow/Green wire and Green/White wire of TW sensor. If reading is about 5 volts, substitute a known good ECU and recheck. If condition is rectified, replace original ECU. If voltage reading is not as specified, repair open Green/White wire between ECU terminal C12 and TW sensor.
  5. If voltage between ground and Yellow/Green wire of sensor harness did not read 5 volts in step 3), turn ignition off. Connect ECU test harness between ECU and ECU connector. Turn ignition on. Measure voltage between ECU terminals C6 (pos.) and C12 (neg.) If voltage reading is about 5 volts, repair open Yellow/Green wire between ECU terminal C6 and TW sensor.
  6. If reading is not about 5 volts, disconnect connector "C" from main wire harness side only. Measure voltage between terminals C6 (pos.) and C12 (neg.). If reading is not about 5 volts, go to next step. If voltage reading is about 5 volts, repair short in Yellow/Green wire between ECU terminal C6 and sensor or repair short in Yellow/Green wire between TW sensor and A/T control unit.
  7. If voltage reading is still not about 5 volts, substitute a known good ECU and recheck. If specified voltage is now available, replace original ECU.
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