Climate Control: Diagnosis Honda Pilot I

How to Retrieve a DTC

The climate control unit has a self-diagnosis function.

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1. Turn the ignition switch ON (II).
2. Press the AUTO button and then the OFF button. Continue to hold both buttons down for 1 minute. NOTE: The system will only display the DTC when the AUTO and OFF buttons are pressed. If you release the buttons, the display will go blank. To return the display, simply press the AUTO then the OFF buttons again. If there is any abnormality in the system, the temperature indicator will light up the segment (A through N) corresponding to the error. If no DTCs are found, go to symptom troubleshooting index. The temperature indicator will then alternate every second between displaying "88" (all segments lit) and the error code segment (A through N). To determine the meaning of the DTC, refer to the DTC Troubleshooting Index for «CLIMATE CONTROL SYSTEM»(ref-174037-S40522919772005051400000) . If there is no abnormality, the segments will not light up. NOTE: If there are no DTC's detected (no opens or shorts in the climate control circuits or sensors), and the system is still not operating properly, check the sensor input to the climate control unit (see «CIRCUIT DIAGRAM»(ref-174043-S19257326202005050300000) ). Cancelling The Self-Diagnosis Function
3. Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis function again to make sure that there are no other malfunctions.

The climate control unit has a self-diagnosis function. To run the self-diagnosis function, do the following

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1. Turn the ignition switch ON (II).
2. Turn the temperature control knob to LO for about 20 seconds, then HI for about 20 seconds.
3. Press the OFF button, then press the recirculation control button to select Recirculation (recirculation indicator comes on).
4. Press and hold the recirculation control button to select Fresh (recirculation indicator goes off). Continue to hold the button. The recirculation indicator comes on for 2 seconds, and then goes off. If the system is OK, the recirculation indicator stays off. If any trouble is found, the recirculation indicator blinks the diagnostic trouble code (DTC) to indicate a faulty circuit or component.
5. After recording the DTC, release the recirculation control button. To determine the meaning of the DTC, refer to the «DTC TROUBLESHOOTING INDEX»(ref-174037-S00562253372005051400000) for rear heater-A/C control system. Cancelling The Self-Diagnosis Function
6. Turn the ignition switch OFF to cancel the self-diagnosis function. After completing repair work, run the self-diagnosis function again to make sure that there are no other malfunctions.

The climate control unit has a mode that displays sensor inputs it receives. This mode shows you what the climate control unit is receiving from each of the sensors, one at a time, and it can help you determine if a sensor is faulty.

Check These Items Before Using The Sensor Input Display Mode

1. Turn the ignition switch ON (II), and check the recirculation door function; press the recirculation button to switch from FRESH to RECIRC. The air volume and sound should change slightly.
2. Set the temperature control knob to the desired test temperature. When selecting the test temperatures, note these items: "Lo" temperature setting will default to MAX COOL, VENT, and RECIRC. "Hi" temperature setting will default to MAX HOT, FLOOR, and FRESH. 61 through 89°F settings will use the automatic climate control logic.
3. Turn the ignition switch OFF.

To Run The Sensor Input Display Mode, Follow These Steps

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1. Turn the ignition switch OFF.
2. Press and hold both the AUTO and RECIRC buttons, then start the engine.
3. After the engine starts, release the buttons. The climate control display will flash the sensor number and then the value for that sensor. Record the value displayed.
4. To advance to the next sensor, press the rear window defogger button.
5. To cancel the sensor input display mode, press the AUTO button, or turn the ignition OFF.

To retrieve the DTC, you must run the self-diagnosis function (see HOW TO RETRIEVE A DTC ). In the case of multiple problems, the respective indicator segments will come on. If indicator segments A, C, E, G, I, and L come on at the same time, there may be an open in the common ground wire of the sensors.

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Rear Heater-A/C Control System

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In case of multiple problems, the recirculation indicator will indicate only the DTC with the least number of blinks. In case of an intermittent failure, the climate control unit will store the DTC until the ignition is turned off.

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DTC Troubleshooting

DTC Troubleshooting Index

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1. Remove the in-car temperature sensor (see «IN-CAR TEMPERATURE SENSOR REPLACEMENT»(ref-174037-S16297388242005051400000) ).
2. Measure the resistance between the No. 1 and No. 2 terminals of the in-car temperature sensor. Check for a change in resistance by heating or cooling the sensor with a hair drier. Is the resistance within the specifications shown on the graph? YES - Go to step 3. NO - Replace the in-car temperature sensor.
3. Disconnect climate control unit connector B (30P).
4. Check for continuity between the No. 18 terminal of climate control unit connector B (30P) and the No. 1 terminal of the in-car temperature sensor 2P connector. Is there continuity? YES - Go to step 5. NO - Repair open in the wire between the climate control unit and the in-car temperature sensor.
5. Check for continuity between the No. 3 terminal of climate control unit connector B (30P) and the No. 2 terminal of the in-car temperature sensor 2P connector. Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the in-car temperature 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. NO - Repair open in the wire between the climate control unit and the in-car temperature sensor.

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1. Remove the in-car temperature sensor (see «IN-CAR TEMPERATURE SENSOR REPLACEMENT»(ref-174037-S16297388242005051400000) ).
2. Test the in-car temperature sensor (see «IN-CAR TEMPERATURE SENSOR TEST»(ref-174037-S09503062202005051400000) ). Is the resistance within the specifications shown on the graph? YES - Go to step 3. NO - Replace the in-car temperature sensor.
3. Disconnect climate control unit connector B (30P).
4. Check for continuity between the No. 18 terminal of climate control unit connector B (30P) and body ground. Is there continuity? YES - Repair short to body ground in the wire between the climate control unit and the in-car temperature sensor. NO - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

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1. Remove the outside air temperature sensor (see «OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT»(ref-174037-S01899023972005051400000) ).
2. Measure the resistance between the No. 1 and No. 2 terminals of the outside air temperature sensor. Dip the sensor in ice water, and measure the resistance. Then pour warm water on the sensor, and check for a change in resistance. Is the resistance within the specification shown on the graph? YES - Go to step 3. NO - Replace the outside air temperature sensor.
3. Disconnect climate control unit connector B (30P).
4. Check for continuity between the No. 19 terminal of climate control unit connector B (30P) and the No. 2 terminal of the outside air temperature sensor 2P connector. Is there continuity? YES - Go to step 5. NO - Repair open in the wire between the climate control unit and the outside air temperature sensor.
5. Check for continuity between the No. 3 terminal of climate control unit connector B (30P) and the No. 1 terminal of the outside air temperature sensor 2P connector. Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the outside air temperature 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. NO - Repair open in the wire between the climate control unit and the outside air temperature sensor.

Scheme 28

1. Remove the outside air temperature sensor (see «OUTSIDE AIR TEMPERATURE SENSOR REPLACEMENT»(ref-174037-S01899023972005051400000) ).
2. Test the outside air temperature sensor (see «OUTSIDE AIR TEMPERATURE SENSOR TEST»(ref-174037-S26373621422005051400000) ). Is the resistance within the specifications shown on the graph? YES - Go to step 3. NO - Replace the outside air temperature sensor.
3. Disconnect climate control unit connector B (30P), and gauge assembly connector A (30P).
4. Check for continuity between the No. 19 terminal of climate control unit connector B (30P) and body ground. Is there continuity? YES - Repair short to body ground in the wire between the climate control unit, the gauge assembly, and the outside air temperature sensor. NO - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

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1. Disconnect the sunlight sensor 2P connector.
2. Disconnect climate control unit connector B (30P).
3. Check for continuity between the No. 20 terminal of climate control unit connector B (30P) and the No. 1 terminal of the sunlight sensor 2P connector. Is there continuity? YES - Go to step 4. NO - Repair open in the wire between the climate control unit and the sunlight sensor.
4. Check for continuity between the No. 3 terminal of climate control unit connector B (30P) and the No. 2 terminal of the sunlight sensor 2P connector. Is there continuity? YES - Go to step 5. NO - Repair open in the wire between the climate control unit and the sunlight sensor.
5. Reconnect the sunlight sensor 2P connector.
6. Reconnect climate control unit connector B (30P).
7. Test the sunlight sensor (see «SUNLIGHT SENSOR TEST»(ref-174037-S31224905422005051400000) ). Is the sunlight sensor OK? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the sunlight 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. NO - Replace the sunlight sensor.

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1. Disconnect the sunlight sensor 2P connector.
2. Disconnect climate control unit connector B (30P).
3. Check for continuity between the No. 20 terminal of climate control unit connector B (30P) and body ground. Is there continuity? YES - Repair short to body ground in the wire between the climate control unit and the sunlight sensor. NO - Go to step 4.
4. Reconnect the sunlight sensor 2P connector.
5. Reconnect climate control unit connector B (30P).
6. Test the sunlight sensor (see «SUNLIGHT SENSOR TEST»(ref-174037-S31224905422005051400000) ). Is the sunlight sensor OK? YES - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Replace the sunlight sensor.

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1. Disconnect the evaporator temperature sensor 2P connector.
2. Measure the resistance between the No. 1 and No. 2 terminals of the evaporator temperature sensor. Is the resistance within the specification shown on the graph? YES - Go to step 3. NO - Replace the evaporator temperature sensor.
3. Disconnect climate control unit connector B (30P).
4. Check for continuity between the No. 21 terminal of climate control unit connector B (30P) and the No. 2 terminal of the evaporator temperature sensor 2P connector. Is there continuity? YES - Go to step 5. NO - Repair open in the wire between the climate control unit and the evaporator temperature sensor.
5. Check for continuity between the No. 3 terminal of climate control unit connector B (30P) and the No. 1 terminal of the evaporator temperature sensor 2P connector. Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the evaporator temperature 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. NO - Repair open in the wire between the climate control unit and the evaporator temperature sensor.

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1. Disconnect the evaporator temperature sensor 2P connector.
2. Test the evaporator temperature sensor (see «EVAPORATOR TEMPERATURE SENSOR TEST»(ref-174036-S12535818712005041500000) ). Is the resistance within the specifications shown on the graph? YES - Go to step 3. NO - Replace the evaporator temperature sensor.
3. Disconnect climate control unit connector B (30P).
4. Check for continuity between the No. 21 terminal of climate control unit connector B (30P) and body ground. Is there continuity? YES - Repair short to body ground in the wire between the climate control unit and the evaporator temperature sensor. NO - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

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1. Test the air mix control motor (see «AIR MIX CONTROL MOTOR TEST»(ref-174036-S08990993432005041500000) ). Is the air mix control motor OK? YES - Go to step 2. NO - Replace the air mix control motor.
2. Disconnect the air mix control motor 7P connector.
3. Disconnect climate control unit connector B (30P), and gauge assembly connector A (30P).
4. Check for continuity between following terminals of climate control unit connector B (30P) and the air mix control motor 7P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-AIR MIX CONTROL MOTOR CONNECTOR CONTINUITY CHART Climate Control Unit Connector B (30P) Terminal Air Mix Control Motor 7P Connector Terminal No. 3 No. 5 No. 10 No. 1 No. 11 No. 2 No. 17 No. 3 No. 23 No. 7 Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the air mix control motor 7P connector. If the connections are good, substitute a known-good air mix control motor, and recheck. If the symptom/indication goes away, replace the original air mix control motor. If the symptom/indication continues, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Repair any open in the wire(s) between the climate control unit, the gauge assembly, and the air mix control motor.

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1. Test the air mix control motor (see «AIR MIX CONTROL MOTOR TEST»(ref-174036-S08990993432005041500000) ). Is the air mix control motor OK? YES - Go to step 2. NO - Replace the air mix control motor.
2. Disconnect the air mix control motor 7P connector.
3. Disconnect climate control unit connector B (30P), and gauge assembly connector A (30P).
4. Check for continuity between body ground and climate control unit connector B (30P) terminals No. 3, 10, 11, 17 and 23 individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit, the gauge assembly, and the air mix control motor. NO - Go to step 5.
5. Turn the ignition switch ON (II), and check the same terminals for voltage. Is there any voltage? YES - Repair any short to power in the wire(s) between the climate control unit, the gauge assembly, and the air mix control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit. NO - Substitute a known-good air mix control motor, and recheck. If the symptom/indication goes away, replace the original air mix control motor. If the symptom/indication continues, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

DTC Indicator Light K: A Problem In The Air Mix Control Linkage, Door, Or Motor

1. Test the air mix control motor (see «AIR MIX CONTROL MOTOR TEST»(ref-174036-S08990993432005041500000) ). Is the air mix control motor OK? YES - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Replace the air mix control motor, or repair the linkage and doors.

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1. Test the mode control motor (see «MODE CONTROL MOTOR TEST»(ref-174036-S28413505772005041500000) ). Is the mode control motor OK? YES - Go to step 2. NO - Replace the mode control motor.
2. Disconnect the mode control motor 7P connector.
3. Disconnect climate control unit connector B (30P), and gauge assembly connector A (30P).
4. Check for continuity between body ground and climate control unit connector B (30P) terminals No. 3, 4, 5, 6, 7, 8, and 9 individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit, the gauge assembly, and the mode control motor. NO - Go to step 5.
5. Turn the ignition switch ON (II), and check the same terminals for voltage. Is there any voltage? YES - Repair any short to power in the wire(s) between the climate control unit, the gauge assembly, and the mode control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit. NO - Go to step 6.
6. Turn the ignition switch OFF, and check for continuity between following terminals of climate control unit connector B (30P) and the mode control motor 7P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-MODE CONTROL MOTOR CONNECTOR CONTINUITY CHART Climate Control Unit Connector B (30P) Terminal Mode Control Motor 7P Connector Terminal No. 3 No. 7 No. 4 No. 3 No. 5 No. 4 No. 6 No. 5 No. 7 No. 6 No. 8 No. 1 No. 9 No. 2 Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the mode control motor 7P connector. If the connections are good, substitute a known-good mode control motor, and recheck. If the symptom/indication goes away, replace the original mode control motor. If the symptom/indication continues, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Repair any open in the wire(s) between the climate control unit and the mode control motor.

DTC Indicator Light M: A Problem In The Mode Control Linkage, Doors, Or Motor

1. Test the mode control motor (see «MODE CONTROL MOTOR TEST»(ref-174036-S28413505772005041500000) ). Is the mode control motor OK? YES - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Replace the mode control motor, or repair the linkage and doors.

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1. Check the No. 56 (40A) fuse in the under-hood fuse/relay box, and the No. 3 (7.5A) fuse in the driver's under-dash fuse/relay box. Are the fuses OK? YES - Go to step 2. NO - Replace the fuse(s), and recheck.
2. Connect the No. 2 terminal of the blower motor 2P connector to body ground with a jumper wire.
3. Turn the ignition switch ON (II). Does the blower motor run? YES - Go to step 4. NO - Go to step 17 .
4. Turn the ignition switch OFF.
5. Disconnect the jumper wire.
6. Disconnect the power transistor 5P connector.
7. Check for continuity between the No. 5 terminal of the power transistor 5P connector and body ground. Is there continuity? YES - Go to step 8. NO - Check for an open in the wire between the power transistor and body ground. If the wire is OK, check for poor ground at G401.
8. Connect the No. 4 and No. 5 terminals of the power transistor 5P connector with a jumper wire.
9. Turn the ignition switch ON (II). Does the blower motor run at high speed? YES - Go to step 10. NO - Repair open in the wire between the power transistor and the blower motor.
10. Turn the ignition switch OFF.
11. Disconnect the jumper wire.
12. Disconnect climate control unit connector B (30P).
13. Check for continuity between the No. 15 and No. 16 terminals of climate control unit connector B (30P) and body ground individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit and the power transistor. NO - Go to step 14.
14. Check for continuity between following terminals of climate control unit connector B (30P) and power transistor 5P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-POWER TRANSISTOR CONNECTOR CONTINUITY CHART Climate Control Unit Connector B (30P) Terminal Power Transistor 5P Connector Terminal No. 15 No. 1 No. 16 No. 3 Is there continuity? YES - Go to step 15. NO - Repair any open in the wire(s) between the climate control unit and the power transistor.
15. Reconnect climate control unit connector B (30P).
16. Test the power transistor (see «POWER TRANSISTOR TEST»(ref-174036-S06062907972005041500000) ). Is the power transistor OK? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at the power transistor 5P 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. NO - Replace the power transistor
17. Disconnect the jumper wire.
18. Disconnect the blower motor 2P connector.
19. Measure the voltage between the No. 1 terminal of the blower motor 2P connector and body ground. Is there battery voltage? YES - Replace the blower motor. NO - Go to step 20.
20. Turn the ignition switch OFF.
21. Remove the blower motor relay from the under-hood fuse/relay box, and test it (see «FUSES & CIRCUIT BREAKERS»(ref-163176) ). Is the relay OK? YES - Go to step 22. NO - Replace the blower motor relay.
22. Measure the voltage between the No. 4 terminal of the blower motor relay 4P socket and body ground. Is there battery voltage? YES - Go to step 23. NO - Replace the under-hood fuse/relay box.
23. Turn the ignition switch ON (II).
24. Measure the voltage between the No. 1 terminal of the blower motor relay 4P socket and body ground. Is there battery voltage? YES - Go to step 25. NO - Repair open in the wire between the No. 3 fuse in the driver's under-dash fuse/relay box and the blower motor relay.
25. Turn the ignition switch OFF.
26. Check for continuity between the No. 2 terminal of the blower motor relay 4P socket and body ground. Is there continuity? YES - Repair open in the YEL/BLK wire between the blower motor relay and the blower motor. NO - Check for an open in the wire between the blower motor relay and body ground. If the wire is OK, check for poor ground at G201.

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1. Check the No. 55 (30A) fuse in the under-hood fuse/relay box, and the No. 3 (7.5A) fuse in the driver's under-dash fuse/relay box. Are the fuses OK? YES - Go to step 2. NO - Replace the fuse(s), and recheck.
2. Connect the No. 2 terminal of the rear blower motor 2P connector to body ground with a jumper wire.
3. Turn the ignition switch ON (II). Does the rear blower motor run? YES - Go to step 4. NO - Go to step 25 .
4. Turn the ignition switch OFF.
5. Disconnect the jumper wire.
6. Disconnect the rear power transistor 4P connector.
7. Check for continuity between the No. 3 terminal of the rear power transistor 4P connector and body ground. Is there continuity? YES - Go to step 8. NO - Check for an open in the wire between the rear power transistor and body ground. If the wire is OK, check for poor ground at G501.
8. Connect the No. 2 and No. 3 terminals of the rear power transistor 4P connector with a jumper wire.
9. Turn the ignition switch ON (II). Does the rear blower motor run at high speed? YES - Go to step 10. NO - Repair open in the wire between the rear power transistor and the rear blower motor.
10. Turn the ignition switch OFF.
11. Disconnect the jumper wire.
12. Disconnect climate control unit connector A (20P).
13. Check for continuity between the No. 3 and No. 4 terminals of climate control unit connector A (20P) and body ground individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit and the rear power transistor. NO - Go to step 14.
14. Check for continuity between following terminals of climate control unit connector A (20P) and rear power transistor 4P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-REAR POWER TRANSISTOR CONNECTOR CONTINUITY CHART Climate Control Unit Connector B (30P) Terminal Rear Power Transistor 4P Connector Terminal No. 3 No. 4 No. 4 No. 1 Is there continuity? YES - Go to step 15. NO - Repair any open in the wire(s) between the climate control unit and the rear power transistor.
15. Reconnect climate control unit connector A (20P).
16. Test the rear power transistor (see «REAR POWER TRANSISTOR TEST»(ref-174038-S12697914662005051700000) ). Is the rear power transistor OK? YES - Go to step 17. NO - Replace the rear power transistor.
17. Disconnect the rear heater-A/C control switch 10P connector.
18. Test the rear heater-A/C control switch (see «REAR HEATER-A/C CONTROL SWITCH TEST»(ref-174038-S17651243872005051700000) ). Is the rear heater-A/C control switch OK? YES - Go to step 19. NO - Replace the rear heater-A/C control switch.
19. Check for continuity between body ground and climate control unit connector A (20P) terminals No. 6, 7, 8, 9, 10, and 20 individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit and the rear heater-A/C control switch. NO - Go to step 20.
20. Turn the ignition switch ON (II), and check the same terminals for voltage. Is there any voltage? YES - Repair any short to power in the wire(s) between the climate control unit and the rear heater-A/C control switch. This short may also damage the rear heater-A/C control switch. Repair the short to power before replacing the rear heater-A/C control switch. NO - Go to step 21.
21. Turn the ignition switch OFF.
22. Check for continuity between the No. 7 terminal of the rear heater-A/C control switch 10P connector and body ground. Is there continuity? YES - Go to step 23. NO - Check for an open in the wire between the rear heater-A/C control switch and body ground. If the wire is OK, check for poor ground at G501.
23. Turn the ignition switch OFF.
24. Check for continuity between following terminals of climate control unit connector A (20P) and the rear heater-A/C control switch 10P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-REAR HEATER-A/C CONTROL SWITCH CONNECTOR CONTINUITY CHART Climate Control Unit Connector A (20P) Terminal Rear Heater-A/C Control Switch 10P Connector Terminal No. 6 No. 6 No. 7 No. 5 No. 8 No. 4 No. 9 No. 3 No. 10 No. 2 No. 20 No. 1 Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector A (20P) and at the rear heater-A/C control switch 10P 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. NO - Repair any open in the wire(s) between the climate control unit and the rear heater-A/C control switch.
25. Disconnect the jumper wire.
26. Disconnect the rear blower motor 2P connector.
27. Measure the voltage between the No. 1 terminal of the rear blower motor 2P connector and body ground. Is there battery voltage? YES - Replace the rear blower motor (see «REAR BLOWER MOTOR REPLACEMENT»(ref-174038-S05476267362005051700000) ). NO - Go to step 28.
28. Turn the ignition switch OFF.
29. Remove the rear blower motor relay from the left side of rear heater-A/C unit, and test it (see «FUSES & CIRCUIT BREAKERS»(ref-163176) ). Is the relay OK? YES - Go to step 30. NO - Replace the rear blower motor relay.
30. Measure the voltage between the No. 1 terminal of the rear blower motor relay 4P connector and body ground. Is there battery voltage? YES - Go to step 31. NO - Repair open in the wire between the No. 55 fuse in the under-hood fuse/relay box and the rear blower motor relay.
31. Turn the ignition switch ON (II).
32. Measure the voltage between the No. 2 terminal of the rear blower motor relay 4P connector and body ground. Is there battery voltage? YES - Go to step 33. NO - Repair open in the wire between the No. 3 fuse in the driver's under-dash fuse/relay box and the rear blower motor relay.
33. Turn the ignition switch OFF.
34. Check for continuity between the No. 4 terminal of the rear blower motor relay 4P connector and body ground. Is there continuity? YES - Repair open in the BLU/YEL wire between the rear blower motor relay and the rear blower motor. NO - Check for an open in the wire between the rear blower motor relay and body ground. If the wire is OK, check for poor ground at G501.

DTC 2: A Problem In The Rear Air Mix Control Linkage, Door, Or Motor

1. Test the rear air mix control motor (see «REAR AIR MIX CONTROL MOTOR TEST»(ref-174038-S36253657972005051700000) ). Is the rear air mix control motor OK? YES - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Go to step 2.
2. Remove the rear air mix control motor (see «REAR AIR MIX CONTROL MOTOR REPLACEMENT»(ref-174038-S33945817822005051700000) ).
3. Check the rear air mix control linkage and door for smooth movement. Do the rear air mix control linkage and door move smoothly? YES - Replace the rear air mix control motor. NO - Repair the rear air mix control linkage and door.

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1. Disconnect the rear air mix control motor 7P connector.
2. Disconnect climate control unit connector A (20P) and B (30P), and gauge assembly connector A (30P).
3. Check for continuity between body ground and climate control unit connector A (20P) terminals No. 1, 2, and 14 individually, and between body ground and climate control unit connector B (30P) terminals No. 3 and 23 individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit, the gauge assembly, and the rear air mix control motor. NO - Go to step 4.
4. Turn the ignition switch ON (II), and check the same terminals for voltage. Is there any voltage? YES - Repair any short to power in the wire(s) between the climate control unit, the gauge assembly, and the rear air mix control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit. NO - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

Scheme 69

1. Disconnect the rear air mix control motor 7P connector.
2. Disconnect climate control unit connector A (20P) and B (30P).
3. Check for continuity between following terminals of climate control unit connectors A (20P) and B (30P) and the rear air mix control motor 7P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-REAR AIR MIX CONTROL MOTOR CONNECTOR CONTINUITY CHART Climate Control Unit Rear Air Mix Control Motor Connector A (20P) Terminal 7P Connector Terminal No. 1 No. 1 No. 2 No. 2 No. 14 No. 3 Connector B (30P) Terminal 7P Connector Terminal No. 3 No. 5 No. 23 No. 7 Is there continuity? YES - Check for loose wires or poor connections at climate control unit connectors A (20P) and B (30P) and at the rear air mix control motor 7P connector. If the connections are good, substitute a known-good rear air mix control motor, and recheck. If the symptom/indication goes away, replace the original rear air mix control motor. If the symptom continues, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit. NO - Repair any open in the wire(s) between the climate control unit and the rear air mix control motor.

Scheme 70

Scheme 71

Scheme 72

Scheme 73

1. Check the No. 3 (7.5A) fuse in the driver's under-dash fuse/relay box. Is the fuse OK? YES - Go to step 2. NO - Replace the fuse, and recheck.
2. Disconnect the recirculation control motor 7P connector.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the No. 1 terminal of the recirculation control motor 7P connector and body ground. Is there battery voltage? YES - Go to step 5. NO - Repair open in the wire between the No. 3 fuse in the driver's under-dash fuse/relay box and the recirculation control motor.
5. Turn the ignition switch OFF.
6. Test the recirculation control motor (see «RECIRCULATION CONTROL MOTOR TEST»(ref-174036-S36089174992005041500000) ). Is the recirculation control motor OK? YES - Go to step 7. NO - Replace the recirculation control motor.
7. Disconnect climate control unit connector B (30P).
8. Check for continuity between the No. 25 and No. 26 terminals of climate control unit connector B (30P) and body ground individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit and the recirculation control motor. NO - Go to step 9.
9. Turn the ignition switch ON (II), and check the same wires for voltage. Is there any voltage? YES - Repair any short to power in the wire(s) between the climate control unit and the recirculation control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit. NO - Go to step 10.
10. Turn the ignition switch OFF.
11. Check for continuity between following terminals of climate control unit connector B (30P) and the recirculation control motor 7P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-RECIRCULATION CONTROL MOTOR CONNECTOR CONTINUITY CHART Climate Control Unit Connector B (30P) Terminal Recirculation Control Motor 7P Connector Terminal No. 25 No. 5 No. 26 No. 7 Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P) and at recirculation control motor 7P 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. NO - Repair any open in the wire(s) between the climate control unit and the recirculation control motor.

ECT Sensor Circuit Troubleshooting

Note. Before performing symptom troubleshooting, check for powertrain DTC (see HOW TO USE THE HONDA DIAGNOSTIC SYSTEM (HDS) ).

Scheme 74

1. Check the malfunction indicator lamp (MIL). Does the malfunction indicator lamp come on? YES - Refer to the fuel and emissions systems DTCs (see «HOW TO USE THE HONDA DIAGNOSTIC SYSTEM (HDS)»(ref-173995-S09596544742005041500000) ). 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 (30P).
5. Turn the ignition switch ON (II).
6. Measure the voltage between the No. 22 terminal of climate control unit connector B (30P) and body ground. Is there about 5V? YES - Check for loose wires or poor connections at climate control unit connector B (30P) 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. NO - Repair open in the wire between the climate control unit and the ECT sensor.

Note. Before performing symptom troubleshooting, check for powertrain DTC (see HOW TO USE THE HONDA DIAGNOSTIC SYSTEM (HDS) )

Scheme 75

Scheme 76

1. Check the No. 3 (7.5A) fuse in the driver's under-dash fuse/relay box. Is the fuse OK? YES - Go to step 2. NO - Replace the fuse, and recheck.
2. Disconnect climate control unit connector B (30P).
3. Turn the ignition switch ON (II).
4. Measure the voltage between the No. 13 terminal of climate control unit connector B (30P) and body ground. Is there battery voltage? YES - Go to step 5. NO - Repair open in the wire between the No. 3 fuse in the driver's under-dash fuse/relay box and the climate control unit.
5. Turn the ignition switch OFF.
6. Check for continuity between the No. 29 terminal of climate control unit connector B (30P) and body ground. Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector B (30P). 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. NO - Check for an open in the wire between the climate control unit and body ground. If the wire is OK, check for poor ground at G401.

Rear Mode Control Motor Circuit Troubleshooting

Note. Before performing symptom troubleshooting, check for powertrain DTC (see HOW TO USE THE HONDA DIAGNOSTIC SYSTEM (HDS) ).

Scheme 77

Scheme 78

Scheme 79

Scheme 80

1. Check the No. 3 (7.5A) fuse in the driver's under-dash fuse/relay box. Is the fuse OK? YES - Go to step 2. NO - Replace the fuse, and recheck.
2. Disconnect the rear mode control motor 7P connector.
3. Turn the ignition switch ON (II).
4. Measure the voltage between the No. 1 terminal of the rear mode control motor 7P connector and body ground. Is there battery voltage? YES - Go to step 5. NO - Repair open in the wire between the No. 3 fuse in the driver's under-dash fuse/relay box and the rear mode control motor.
5. Turn the ignition switch OFF.
6. Test the rear mode control motor (see «REAR MODE CONTROL MOTOR TEST»(ref-174038-S20291205092005051700000) ). Is the rear mode control motor OK? YES - Go to step 7. NO - Replace the rear mode control motor.
7. Disconnect climate control unit connector A (20P).
8. Check for continuity between the No. 11 and No. 12 terminals of climate control unit connector A (20P) and body ground individually. Is there continuity? YES - Repair any short to body ground in the wire(s) between the climate control unit and the rear mode control motor. NO - Go to step 9.
9. Turn the ignition switch ON (II), and check the same terminals for voltage. Is there any voltage? YES - Repair any short to power in the wire(s) between the climate control unit and the rear mode control motor. This short may also damage the climate control unit. Repair the short to power before replacing the climate control unit. NO - Go to step 10.
10. Turn the ignition switch OFF.
11. Check for continuity between following terminals of climate control unit connector A (20P) and the rear mode control motor 7P connector. CLIMATE CONTROL UNIT CONNECTOR-TO-REAR MODE CONTROL MOTOR CONNECTOR CONTINUITY CHART Climate Control Unit Connector A (20P) Terminal Rear Mode Control Motor 7P Connector Terminal No. 11 No. 5 No. 12 No. 7 Is there continuity? YES - Check for loose wires or poor connections at climate control unit connector A (20P) and at rear mode control motor 7P 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. NO - Repair any open in the wire(s) between the climate control unit and the rear mode control motor.

In-car Temperature Sensor Test

Check for a change in resistance by heating or cooling the sensor with a hair drier.

Compare the resistance reading between the No. 1 and No. 2 terminals of the in-car temperature sensor with the specifications shown in the graph; the resistance should be within the specifications.

Scheme 81

Scheme 82

Scheme 83

1. Remove the in-car temperature sensor (A) from the dashboard, then disconnect the 2P connector (B) and the air hose (C). Be careful not to damage the sensor or the dashboard.
2. Install the sensor in the reverse order of removal. Be sure to connect the air hose securely.

Outside Air Temperature Sensor Test

Dip the sensor in ice water, and measure the resistance. Then pour warm water on the sensor, and check for a change in resistance.

Compare the resistance reading between the No. 1 and No. 2 terminals of the outside air temperature sensor with the specifications shown in the graph; the resistance should be within the specifications.

Scheme 84

Scheme 85

Scheme 86

1. Lift the tab (A) to release the lock, and remove the outside air temperature sensor (B) from the back of the front bumper beam. Disconnect the 2P connector (C) from the outside air temperature sensor.
2. Install the sensor in the reverse order of removal.

Sunlight Sensor Test

Turn the ignition switch ON (II). Measure the voltage between the terminals with the (+) probe on the No. 1 terminal and the (-) probe on the No. 2 terminal with the 2P connector connected. The voltage readings will not change under the light of a flashlight or a fluorescent lamp. Voltage should be

Scheme 87

1. 3.6-3.7 V or more with the sensor out of direct sunlight.
2. 3.3-3.5 V or less with the sensor in direct sunlight.

Scheme 88

1. Remove the sunlight sensor (A) from the dashboard, then disconnect the 2P connector (B). Be careful not to damage the sensor or the dashboard.
2. Install the sensor in the reverse order of removal.

Scheme 89

Scheme 90

1. Remove the center front covers and the center lower cover (see «CENTER CONSOLE REMOVAL/INSTALLATION»(ref-174030-S31369994412005042500000) ).
2. Remove the screws, and remove the climate control unit (A) with the brackets from the dashboard, then disconnect the connectors (B).
3. Remove the screws and the climate control unit (A) from the brackets (B).
4. Install the control unit in the reverse order of removal. After installation, operate the control unit controls to see whether it works properly.
5. Run the self-diagnosis function to confirm that there are no problems in the system (see «RUNNING THE SELF-DIAGNOSIS FUNCTION»(ref-174037-S07730042152005051400000) ).

Scheme 91

Scheme 92

1. Discharge the static electricity (which accumulated on you when you removed the climate control unit) by touching the door striker or other body parts.
2. Remove the self-tapping screws, then carefully separate the climate control unit cover (A) and the control unit (B) from the control unit display (C). Do not kink or pull on the wires between the display and the control unit. Do not touch the electronic components on the printed circuit board in the control unit.
3. Remove the bulb(s) with a flat-tip screwdriver.
4. Install the bulb(s) in the reverse order of removal.