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ECT Sensor Circuit Troubleshooting.

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2004 Honda Odyssey, 2003 Honda Odyssey, 2002 Honda Odyssey, 2001 Honda Odyssey, and 2000 Honda Odyssey. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Before performing symptom troubleshooting check for powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).
  1. Check the malfunction indicator lamp (MIL)

    Does the malfunction indicator lamp come on? 

    1. YES  - Refer to the powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).
    2. NO  -
      1. Without Navigation System: Go to step 2.
      2. With Navigation System: Go to step  7 .
  2. Turn the ignition switch OFF.
  3. Disconnect the ECT sensor 2P connector.
  4. Disconnect climate control unit connector A (8P).
  5. Turn the ignition switch ON (II).
  6. Measure the voltage between the No. 3 terminal of climate control unit connector A (8P) and body ground.
    Fig 1: Measuring Voltage Between No. 3 Terminal Of Climate Control Unit Connector A (8P) & Body Ground
    G01520113Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    1. YES  - Check for loose wires or poor connections at climate control unit connector A (8P) and at the ECT sensor 2P connector If the connections are good substitute a known good climate control unit and recheck If the symptom/indication goes away replace the original climate control unit.
    2. NO  - Repair open in the wire between the climate control unit and the ECT sensor.
  7. Turn the ignition switch OFF.
  8. Disconnect the ECT sensor 2P connector.
  9. Disconnect climate control unit connector B (26P).
  10. Turn the ignition switch ON (II).
  11. Measure the voltage between the No. 22 terminal of climate control unit connector B (26P) and body ground.
    Fig 2: Measuring Voltage Between No. 22 Terminal Of Climate Control Unit Connector B (26P) & Body Ground
    G01520114Courtesy of AMERICAN HONDA MOTOR CO., INC.

    Is there about 5 V? 

    1. YES  - Check for loose wires or poor connections at climate control unit connector B (26P) and at the ECT sensor 2P connector If the connections are good substitute a known-good climate control unit and recheck If the symptom/indication goes away replace the original climate control unit.
    2. NO  - Repair open in the wire between the climate control unit and the ECT sensor.
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