LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Acura >> 2003 >> MDX Base >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Climate Control System >> ECT Sensor Circuit Troubleshooting
April 5, 2026: LEMON Manuals is launched! Read the announcement.

ECT Sensor Circuit Troubleshooting

  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  - Go to step 2.
  2. Turn the ignition switch OFF.
  3. Disconnect the ECT sensor 2P connector.
  4. Disconnect climate control unit connector B (26P).
  5. Turn the ignition switch ON (II).
  6. Measure the voltage between the No. 22 terminal of climate control unit connector B (26P) and body ground.
    Fig 1: Measuring Voltage Between No. 22 Terminal Of Climate Control Unit Connector B And Body Ground
    G03641848Courtesy 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.