Air Conditioning System - Diagnostics Toyota Highlander I

HOW TO PROCEED WITH TROUBLESHOOTING

1. VEHICLE BROUGHT TO WORK SHOP
2. CUSTOMER PROBLEM ANALYSIS (See «CUSTOMER PROBLEM ANALYSIS CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) )
3. CHECK AND CLEAR DTC (See «PRE-CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) )
4. PROBLEM SYMPTOM CONFIRMATION SYMPTOM OCCURS (GO TO STEP 6 ) SYMPTOM DOES NOT OCCUR (GO TO STEP 5)
5. SYMPTOM SIMULATION (See «HOW TO PROCEED WITH TROUBLESHOOTING»(ref-190850-S03015087602005091700000) )
6. DTC CHECK (See «PRE-CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) ) MALFUNCTION CODE (GO TO STEP 7) NORMAL CODE (GO TO STEP 8 )
7. DTC CHART (See «DIAGNOSTIC TROUBLE CODE CHART»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics__diagnostic-trouble-code-chart) ) GO TO STEP 10
8. PROBLEM SYMPTOMS TABLE (See «PROBLEM SYMPTOMS TABLE»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) )
9. ACTUATOR CHECK (See «PRE-CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) )
10. CIRCUIT INSPECTION (See «DTC B1411/11 ROOM TEMPERATURE SENSOR CIRCUIT»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) and «COMPRESSOR CIRCUIT»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) )
11. IDENTIFICATION OF PROBLEM
12. PARTS INSPECTION
13. REPAIR
14. CONFIRMATION TEST
15. END

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1. LIST OF OPERATION METHODS By operating each of the A/C control switches as shown the diagram below, it is possible to enter the diagnosis check mode.
2. INDICATOR CHECK Turn the ignition switch ON while pressing the A/C control AUTO switch and R/F switch simultaneously. Check that the indicators light up and go off at second intervals 4 times in succession. NOTE: After the indicator check is completed, the system enters the DTC begins automatically. Press the OFF switch when desiring to cancel the check mode.
3. DTC CHECK (SENSOR CHECK) Perform an indicator check. After the indicator check is completed, the system enters the DTC check mode automatically. Read the code displayed on the panel. Refer to the list of codes «DIAGNOSTIC TROUBLE CODE CHART»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics__diagnostic-trouble-code-chart) when reading the codes. (Trouble code are output at the temperature display.) If the slower display is desired, press the FRONT DBF switch and change it to stepped operation. Each time the FRONT DBF switch is pressed, the display changes by 1 step.
4. CLEARING DTC To clear diagnostic trouble code, there are 2 ways: During sensor check, press the FRONT DBF switch and REAR DBF switch at the same time. Pull the ECU-B fuse in engine room J/B for 20 sec. or longer to clear the DTC memory.
5. ACTUATOR CHECK After entering the DTC check mode (Sensor Check Mode) press the R/F switch. Since each damper, motor and relay automatically operates at 1 sec. intervals beginning in order from 10 in the temperature display, check the temperature and air flow visually and by hand. If the slower display is desired, press the FRONT DBF switch and change it to step operation. Each time the FRONT DBF switch is pressed, the display changes by 1 step. NOTE: Code are displayed in order from the smaller to the larger numbers. To cancel the check mode, press the OFF switch. DISPLAY CODE Step No. Display code Conditions Blower level Air flow vent Air inlet damper Magnetic clutch Air mix damper 1 0 0 FACE FRESH OFF "COOL" side (Full closed) 2 1 1 FACE FRESH OFF "COOL" side (Full closed) 3 2 17 FACE FRESH ON "COOL" side (Full closed) 4 3 17 FACE FRESH ON "COOL" side (Full closed) 5 4 17 FACE RECIRCULATION ON "COOL"/ "WARM " (50 % open) 6 5 17 B/L RECIRCULATION ON "COOL"/ "WARM " (50 % open) 7 6 17 FOOT RECIRCULATION ON "WARM" side (Full opened) 8 7 17 FOOT RECIRCULATION ON "WARM" side (Full opened) 9 8 17 FOOT/ DEF RECIRCULATION ON "WARM" side (Full opened) 10 9 31 DEF RECIRCULATION ON "WARM" side (Full opened)

DIAGNOSTIC TROUBLE CODE CHART

If malfunction code is displayed during the DTC check (sensor check), check the circuit listed for that code in the table below (Proceed to the page given for that circuit).

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Note. *1 : If the room temp, is approx. -18.6° C (-3.7° F) or lower, DTCB1411/11 may be output even though the system is normal. *2 : If the ambient temp, is approx. -52.9° C (-61.4° F) or lower, DTC B1412/12 may be output even though the system is normal. *3 : If the check is being performed in a dark place, DTC B1421721 (solar sensor circuit abnormal) could be displayed. *4 : The A/C amplifier assy memorizes the DTC of the respective malfunction it has occurred for the period of the time indicated in the brackets. *5 : Compressor lock (DTC B1422/22) is indicated only for a current malfunction. (See DTC B1422/22 COMPRESSOR LOCK SENSOR CIRCUIT ) To confirm DTC B1422/22, preform the following steps. With the engine ON, enter the DTC check mode. Press the R/F switch to enter actuator check mode, and set the operation to Step No. 3. Press the AUTO switch to return to DTC check mode. The DTC is displayed after approx. 3 sees.

DIAGNOSTIC TROUBLE CODES (DTC) LIST

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Circuit Description

This sensor detects the temperature inside the cabin and sends the appropriate signals to the A/C amplifier assy.

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Inspection Procedure

Note. In case of using the TOYOTA hand-held tester, start the inspection step 1 and in case of not using the TOYOTA hand-held tester, start from step 2 .

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1. READ VALUE OF OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Connect the TOYOTA hand-held tester to the DLC3. Check the cooler (room temp, sensor) thermistor using DATA LIST. NOTE: When checking using DTC chart, go to OK:A. When checking using problem symptoms table, go to OK:B. OK : A: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY OK : B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (TR, SG-3) Remove A/C amplifier assy with connectors still connected. Turn ignition switch ON. Measure voltage between terminals TR and SG-3 of A/C amplifier assy connector at each temperature. Voltage: at 25 °C (77 ° F) : 1.8 - 2.2 V at 40 °C (104° F) : 1.2 - 1.6 V NOTE: As the temperature increases, the voltage decreases. OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY NG : Go To Next Step.
3. INSPECT COOLER (ROOM TEMP. SENSOR) THERMISTOR Remove cooler (room temp, sensor) thermistor. Measure resistance between terminals 1 and 2 of cooler (room temp, sensor) connector at each temperature. Resistance: at 25 °C (77° F): 1.62 - 1.79 kohms at 40 °C (104° F): 0.85 - 0.95 kohms As the temperature increases, the resistance decreases. NG : REPLACE COOLER (ROOM TEMP. SENSOR) THERMISTOR OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN COOLER (ROOM TEMP. SENSOR) THERMISTOR AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This sensor detects the temperature outside the cabin and sends the appropriate signals to the A/C amplifier assy.

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Note. In case of using the TOYOTA hand-held tester, start the inspection step 1 and in case of not using the TOYOTA hand-held tester, start from step 2 .

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1. READ VALUE OF OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Connect the TOYOTA hand-held tester to the DLC3. Check the cooler (ambient temp, sensor) thermistor using DATA LIST. NOTE: When checking using DTC chart, go to OK:A. When checking using problem sympthoms table, go to OK:B. OK : A: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY OK : B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (TAM, SG-5) Remove A/C amplifier assy with connectors still connected. Turn ignition switch ON. Measure voltage between terminals TAM and SG-5 of A/C amplifier assy connector at each temperature. Voltage: at 25 °C (77 °F) : 1.4 - 1.8 V at 40 °C (104 °F) : 0.8 - 1.2 V NOTE: As the temperature increases, the voltage decreases. OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY NG : Go To Next Step.
3. INSPECT COOLER (AMBIENT TEMP. SENSOR) THERMISTOR Remove cooler (ambient temp, sensor) thermistor. Measure resistance between terminals 1 and 2 of cooler (ambient temp, sensor) thermistor connector at each temperature. Resistance: at 25 °C (77 °F) : 1.65 - 1.75 kohms at 40 °C (104 °F) : 0.85 - 0.95 kohms HINT: As the temperature increases, the resistance decreases. NG : REPLACE COOLER (AMBIENT TEMP. SENSOR) THERMISTOR OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN COOLER (AMBIENT TEMP. SENSOR) THERMISTOR AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This sensor detects the temperature inside the cooling unit and sends the appropriate signals to the A/C amplifier assy.

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Note. In case of using the TOYOTA hand-held tester, start the inspection step 1 and in case of not using the TOYOTA hand-held tester, start from step 2.

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1. READ VALUE OF OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Connect the TOYOTA hand-held tester to the DLC3. Check the cooler thermistor No. 1 using DATA LIST. NOTE: When checking using DTC chart, go to OK:A. When checking using problem sympthoms table, go to OK:B. OK : A: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY OK : B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (TE, SG-1) Remove A/C amplifier assy with connectors still connected. Turn ignition switch ON. Measure voltage between terminals TE and SG-1 of A/C amplifier assy connector at each temperature. Voltage at 0° C (3° F) : 2.0 - 2.4 V at 15° C (59° F) : 1.4 - 1.8 V OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY NG : Go To Next Step.
3. INSPECT COOLER THERMISTOR NO. 1 Remove cooler thermistor No. 1. Check resistance between terminals 1 and 2 of cooler thermistor No. 1 at each temperature, as shown in the chart. Resistance: NG : REPLACE COOLER THERMISTOR NO. 1 OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN COOLER THERMISTOR NO. 1 AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

A photo diode in the solar sensor detects solar radiation and sends signals to the A/C amplifier assy.

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Note. In case of using the TOYOTA hand-held tester, start the inspection step 1 and in case of not using the TOYOTA hand-held tester, start from step 2.

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1. READ VALUE OF OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Connect the TOYOTA hand-held tester to the DLC3. Check the cooler (solar sensor) thermistor using DATA LIST. NOTE: When checking using DTC chart, go to OK: A. When checking using problem sympthoms table, go to OK: B. OK : A: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY OK : B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (TS, S5-3) Remove A/C amplifier assy with connectors still connected. Turn ignition switch ON. Measure voltage between terminals TS and S5-3 of A/C amplifier assy connector when the cooler (solar sensor) thermistor is subject to an electric light, and when the cooler (solar sensor) thermistor is covered by a cloth Voltage: Sensor subject to electric light: Below 4.0 V Sensor is covered by a cloth: 4.0 - 4.5 V NOTE: As the inspection light is moved away from the sensor, the voltage increases. OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
3. INSPECT COOLER (SOLAR SENSOR) THERMISTOR Remove cooler (solar sensor) thermistor. Cover sensor with a cloth. Measure resistance between terminals 1 and 2 of cooler (solar sensor) thermistor connector Resistance: infinite ohms (No continuity) NOTE: Connect the positive (+) lead to ohmmeter to terminal 2 and negative (-) lead to terminal 1 of the solar sensor. Remove the cloth from the cooler (solar sensor) thermistor and subject the sensor to electric light Measure resistance between terminals 2 and 1 of solar sensor. Resistance: Continuity NOTE: Connect the positive (+) lead to ohmmeter to terminal 1 and negative (-) lead to terminal 2 of the solar sensor. NG : REPLACE COOLER (SOLAR SENSOR) THERMISTOR OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN COOLER (SOLAR SENSOR) THERMISTOR AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This sensor sends 4 pulses per engine revolution to the ECM.

If the number ratio of the compressor speed divided by the engine speed is smaller than a predetermined value, the ECM turns the compressor OFF. And the indicator flashes at about 1 second intervals.

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1. INSPECT ECM (LCK1) Remove the ECM with connectors still connected. Start the engine and push AUTO switch. Inspect voltage between terminal LCK1 of ECM connector and body ground. Voltage: 10 - 14 V OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT COOLER COMPRESSOR ASSY Disconnect the cooler compressor assy connector. Measure resistance between terminals 1 and 2 of cooler compressor assy connector. Resistance: at 20° C (68° F): 165 - 205 ohms NG : CHECK AND REPLACE COOLER COMPRESSOR ASSY OK : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR (BETWEEN ECM AND COOLER COMPRESSOR ASSY) NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN COOLER COMPRESSOR ASSY AND BODY GROUND) NG : REPAIR OR REPLACE HARNESS AND CONNECTOR OK : CHECK AND REPLACE ECM

The pressure switch sends the appropriate signals to the ECM when the A/C refrigerant pressure drops too low or rises too high. When the ECM receives these signals, it outputs signals via the ECM to switch OFF the compressor relay and turns the magnetic clutch OFF.

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1. INSPECT ECM (PRE) Install the manifold gauge set. Turn ignition switch ON. Check voltage between terminal PRE of ECM connector and body ground when refrigerant pressure is changed. The voltage changes with refrigerant pressure (Scheme 39) Voltage: OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG: Go To Next Step.
2. INSPECT COOLER REFRIGERANT LIQUID PIPE A (PRESSURE SWITCH) Turn ignition switch ON. Check continuity between terminals 1 and 4 of cooler refrigerant liquid pipe A (pressure switch) when refrigerant pressure is changed. The continuity changes with refrigerant pressure (Scheme 41) Continuity: NG: REPLACE COOLER REFRIGERANT LIQUID PIPE A OK: Go To Next Step.
3. CHECK HARNESS AND CONNECTOR (BETWEEN PRESSURE SWITCH AND ECM) NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN PRESSURE SWITCH AND BODY GROUND) NG: REPAIR OR REPLACE HARNESS OR CONNECTOR OK: REPAIR OR REPLACE ECM

This sensor detects the position of the air mix damper servo sub-assy and sends the appropriate signals to the A/C amplifier assy. The position sensor is built into the air mix servo sub-assy.

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Note. In case of using the TOYOTA hand-held tester, start the inspection step 1 and in case of not using the TOYOTA hand-held tester, start from step 2.

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1. READ VALUE OF OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Connect the TOYOTA hand-held tester to the DLC3. Check the current position of air mix damper servo sub-assy and the target position of air mix damper servo sub-assy. NOTE: When checking using DTC chart, go to OK: A. When checking using problem sympthoms table, go to OK: B. OK : A: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY OK : B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (TP, SG-1) Remove the A/C amplifier assy with connectors still connected. Turn ignition switch ON. Change the set temperature to activate the air mix damper servo sub-assy and measure the voltage between terminals TP and SG-1 of A/C amplifier assy. Voltage: MAX. COOL: 3.5 - 4.5 V MAX. WARM: 0.5 - 1.8 V NOTE: As the set temperature increases, the voltage decreases gradually without interruption. OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY NG : Go To Next Step.
3. INSPECT AIRMIX DAMPER SERVO SUB-ASSY Remove the air mix damper servo sub-assy. Measure resistance between terminals 1 and 2 of air mix damper servo sub-assy connector. Resistance: 4.2 - 7.8 kohms While operating air mix damper servo sub-assy as shown in the procedure «DTC B1441/41 AIR MIX DAMPER CONTROL SERVOMOTOR CIRCUIT (PASSENGER SIDE)»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) , measure resistance between terminals 1 and 3 of air mix damper servo sub-assy. Resistance: MAX. COOL: 3.4 - 6.2 kohms MAX. WARM: 0.8 - 1.6 kohms NOTE: As the air mix damper servo sub-assy moves from cool side to warm side, the resistance decreases gradually without interruption. NG : REPLACE AIRMIX DAMPER SERVO SUB-ASSY OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN AIR MIX DAMPER SERVO SUB-ASSY AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This sensor detects the position of the mode damper servo sub-assy and sends the appropriate signals to the A/C amplifier assy. The position sensor is built into the mode damper servo sub-assy.

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Note. In case of using the TOYOTA hand-held tester, start the inspection step 1 and in case of not using the TOYOTA hand-held tester, start from step 2.

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1. READ VALUE OF OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Connect the TOYOTA hand-held tester to the DLC3. Check the current position of mode damper servo sub-assy and the target position of mode damper servo sub-assy. NOTE: When checking using DTC chart, go to OK: A. When checking using problem sympthoms table, go to OK: B. OK : A: CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY OK : B: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (TPO, SG) Remove the A/C amplifier assy with connectors still connected. Turn ignition switch ON. Measure voltage between terminals TPO and SG of A/C amplifier assy. Voltage: FACE: 3.5 - 4.5 V DEF: 0.5 - 1.5 V NOTE: As the air outlet servomotor is moved from FACE side to DEF side, the voltage decreases gradually with out interruption. OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY NG : Go To Next Step.
3. INSPECT MODE DAMPER SERVO SUB-ASSY Remove the mode damper servo sub-assy. Measure resistance between terminals 1 and 2 of mode damper servo sub-assy connector. Resistance: 4.2 - 7.8 kohms While operating mode damper servo sub-assy as in the procedure «DTC B1443/43 AIR OUTLET DAMPER CONTROL SERVOMOTOR CIRCUIT»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) , measure resistance between terminal 1 and 3 of mode damper servo sub-assy. Resistance: DEF: 3.4 - 6.2 kohms FACE: 0.8- 1.6 kohms NOTE: As the mode damper servo sub-assy moved from DEF side to FACE side, the resistance decreases gradually with out interruption. NG : REPLACE MODE DAMPER SERVO SUB-ASSY OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN MODE DAMPER SERVO SUB-ASSY AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This air mix damper servo sub-assy is controlled by the A/C amplifier assy and moves the air mix damper servo sub-assy to the desired position.

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1. PERFORM ACTIVE TEST BY OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Set to actuator check mode (See «PRE-CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) ). Press the DEF switch and change to step operation. Check the air flow temperature by hand. AIR MIX DAMPER OPERATION AND DISPLAY CODE Display Code Air Mix Damper Operation 0 COOL Side (-5 % Open) 1 COOL Side (-5 % Open) 2 COOL Side (-5 % Open) 3 COOL Side (-5 % Open) 4 COOL/WARM (50 % Open) 5 COOL/WARM (50 % Open) 6 WARM Side (105 % Open) 7 WARM Side (105 % Open) 8 WARM Side (105 % Open) 9 WARM Side (105 % Open) OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT AIRMIX DAMPER SERVO SUB-ASSY Remove the air mix damper servo sub-assy. Connect the positive (+) lead from the battery to terminal 4 and negative (-) lead to terminal 5, then check that the lever turns to COOL side smoothly. Connect the positive (+) lead from the battery to terminal 5 and negative (-) lead to terminal 4, then check that the lever turns to WARM side smoothly. NG : REPLACE AIRMIX DAMPER SERVO SUB-ASSY OK : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR (BETWEEN AIR MIX DAMPER SERVO SUB-ASSY AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This circuit turns the servomotor and changes each mode damper position by the signals from the A/C amplifier assy. When the AUTO switch is on, the A/C amplifier assy changes the mode automatically between (FACE), (BI-LEVEL) and (FOOT) according to the temperature setting.

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1. PERFORM ACTIVE TEST BY OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Warm up engine. Set to actuator check mode (See «PRE-CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) ). Press the DEF switch and change it to step operation Press the DEF switch and check that the air flow by hand. AIR FLOW CONDITION AND DISPLAY CODE Display Code Air Flow Condition 0 FACE 1 FACE 2 FACE 3 FACE 4 FACE 5 B/L 6 FOOT 7 FOOT 8 FOOT/DEF 9 DEF OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT MODE DAMPER SERVO SUB-ASSY Remove the air mode damper servo sub-assy. Connect the positive (+) lead from the battery to terminal 4 and negative (-) lead to terminal 5 then check that the lever turns to DEF position. Connect the positive (+) lead from the battery to terminal 5 and negative (-) lead to terminal 4 then check that the lever turn to FACE position. NG : REPLACE MODE DAMPER SERVO SUB-ASSY OK : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR (BETWEEN MODE DAMPER SERVO SUB-ASSY AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This DTC is output when communication stops.

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1. CHECK MULTIPLEX COMMUNICATION SYSTEM NG : REPAIR OR REPLACE ECM OK : REPLACE AIR CONDITIONER AMPLIFIER ASSY

This is the power source for the A/C amplifier assy and servomotor, etc.

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1. CHECK FUSE (HEATER, AM1 FUSES) Remove the HEATER, AM1 fuses from the instrument panel J/B. Check that the continuity exists of HEATER, AM1 fuses. NG : REPLACE FUSE OK : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (IG+, GND) Remove the A/C amplifier assy with connectors still connected. Measure voltage between terminals IG+ and GND of the A/C amplifier assy. Voltage: 10 - 14 V OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR (BETWEEN A/C AMPLIFIER ASSY AND BODY GROUND) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR (BETWEEN A/C AMPLIFIER ASSY AND BATTERY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This is the back-up power source for the A/C amplifier assy. Power is supplied even when the ignition switch is off and is used for diagnostic trouble code memory, etc.

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1. CHECK FUSE (ECU-B FUSE) Remove the ECU-B fuse from the engine room J/B. Check that the continuity exists of ECU-B fuse. NG : REPLACE FUSE OK : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (+B) Remove the A/C amplifier assy with connectors still connected. Measure voltage between terminals +B of A/C amplifier assy and body ground. Voltage: 10 - 14 V OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR(BETWEEN A/C AMPLIFIER ASSY AND BATTERY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

This circuit supplies power to the A/C amplifier assy. It supplies power to the illumination for the clock.

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1. CHECK FUSE(RADIO NO. 2, AM1 FUSES) Remove the RADIO No. 2, AM1 fuses from the insturment panel J/B. Check that the continuity exixts of RADIO No. 2, AM1 fuses. NG : REPLACE FUSE OK : Go To Next Step.
2. INSPECT AIR CONDITIONER AMPLIFIER ASSY (ACC) Remove the A/C amplifier assy with connectors still connected. Turn ignition switch ACC. Measure voltage between terminals ACC of the A/C amplifier assy and body ground Voltage: 10 - 14 V OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR(BETWEEN A/C AMPLIFIER ASSY AND BATTERY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

The recirculation damper servo sub-assy is controlled by the A/C amplifier assy and move the recirculation damper servo sub-assy to the desired position

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1. PERFORM ACTIVE TEST BY OBD II SCAN TOOL OR TOYOTA HAND-HELD TESTER Remove the glove box to see and check the recirculation damper servo sub-assy operation. Set to the actuator check mode (See «PRE-CHECK»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) ). Press the DEF switch and change it to step operation. Press the DEF switch in order and check the operation of recirculation damper servo sub-assy. RECIRCULATION DAMPER POSITION AND DISPLAY CODE Display Code Recirculation Damper Position 0 FRESH 1 FRESH 2 FRESH 3 FRESH 4 RECIRCURATION 5 RECIRCURATION 6 RECIRCURATION 7 RECIRCURATION 8 RECIRCURATION 9 RECIRCURATION OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT RECIRCULATION DAMPER SERVO SUB-ASSY Remove the recirculation damper servo sub-assy. Connect the positive (+) lead to from the battery to terminal 5 and negative (-) lead to terminal 2, then check that the lever turns to FRESH side smoothly. Connect the positive (+) lead to from the battery to terminal 1 and negative (-) lead to terminal 5, then check that the lever turns to RECIRCULATION side smoothly. NG : REPLACE RECIRCULATION DAMPER SERVO SUB-ASSY OK : Go To Next Step.
3. CHECK HARNESS AND CONNECTOR(BETWEEN RECIRCULATON DAMPER SERVO SUB-ASSY AND A/C AMPLIFIER ASSY) NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE AIR CONDITIONER AMPLIFIER ASSY

The blower motor is operated by signals from the A/C amplifier assy. Blower motor speed signals are transmitted by changes in the Duty Ratio.

Duty Ratio

The duty ratio is the ratio of the period of continuity in one cycle. For example, if A is the period of continuity in one cycle, and B is the period of non-continuity, then.

Scheme 75

Scheme 76

Scheme 77

1. INSPECT COOLING UNIT MOTOR SUB-ASSY W/FAN Remove cooling unit motor sub-assy w/ fan. Connect positive (+) lead connected to terminal 2 of blower motor connector, negative (-) lead to terminal 1. Standard: Cooling unit motor sub-assy w/ fan operates smoothly. NG : REPLACE COOLING UNIT MOTOR SUB-ASSY W/FAN OK : Go To Next Step.
2. CHECK HARNESS AND CONNECTOR NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE BLOWER MOTOR CONTROL

The heater relay is switched on by signals from the A/C amplifier assy. It supplies power to the blower motor

Scheme 78

Scheme 79

Scheme 80

1. CHECK FUSE(15 A HEATER, 50 A HEATER, AM1 FUSES) Remove the 15 A HEATER, 50 A HEATER, AM1 fuses from the instrument panel J/B. Check that the continuity exists of 15 A HEATER, 50 A HEATER, AM1 fuses. NG : REPLACE FUSE OK : Go To Next Step.
2. INSPECT HEATER BLOWER MOTOR RELAY ASSY Check that the continuity exists between each pair of terminals of heater blower motor relay assy, as shown in «HEATER BLOWER MOTOR RELAY ASSY CONTINUITY»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) . HEATER BLOWER MOTOR RELAY ASSY CONTINUITY Tester Connection Specified Condition 1 - 4 No Continuity 2 - 4 Continuity 3 - 5 62.5 - 90.9 ohms Apply battery voltage between terminals 3 and 5. Check continuity each pair of terminals, as shown in «CONTINUITY»(/toyota/highlander/i-2001-2003/remont/automatic-hvac-system/#air-conditioning-system-diagnostics) . CONTINUITY Tester Connection Specified Condition 1 - 2 Continuity 2 - 4 No Continuity NG : REPLACE HEATER BLOWER MOTOR RELAY ASSY OK : Go To Next Step.
3. INSPECT AIR CONDITIONER AMPLIFIER ASSY(HR) Remove the A/C amplifier assy with connectors still connected. Measure voltage between terminal HR of A/C amplifier assy and body ground when ignition switch is ON and OFF Voltage: Ignition switch OFF: 0 V Ignition switch ON (Blower switch ON): Below 1 V Ignition switch ON (Blower switch OFF): 10 - 14 V OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : REPAIR OR REPLACE AIR CONDITIONER AMPLIFIER ASSY

The A/C amplifier assy outputs the magnetic clutch ON signal from terminal MPX to the ECM receives this signal, it sends a signal from terminal ACMG and switches the magnetic clutch relay ON, thus turning on the magnetic clutch.

Scheme 81

Scheme 82

Scheme 83

Scheme 84

1. INSPECT ECM (ACMG) Remove ECM with connectors still connected. Start the engine and push AUTO switch. Check voltage between terminal ACMG of ECM and body ground when magnetic clutch is ON and OFF by A/C switch. Voltage: A/C switch ON: Below 1 V A/C switch OFF: 10 - 14 V OK : PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOM TABLE NG : Go To Next Step.
2. INSPECT MAGNET-CLUTCH RELAY Remove the magnetic-clutch relay from engine room R/B. Check continuity between each pair of terminal shown below of magnetic-clutch relay. Continuity (Resistance): MAGNET CLUTCH RELAY CONTINUITY Tester Connection Specified Condition 1 -2 Continuity (62.5 - 90.9 ohms) 3 - 5 No Continuity Apply battery voltage between terminal 1 and 2. Check that continuity exists between terminals 3 and 5. NG : REPLACE MAGNET-CLUTCH RELAY OK : Go To Next Step.
3. CHECK MAGNET CLUTCH ASSY Disconnect the connector from the cooler compressor assy. Connect the positive (+) lead from the battery to terminal 3 and negative (-) lead to terminal body ground, then check that the magnetic clutch assy is engaged. NG : REPLACE MAGNET CLUTCH ASSY OK : Go To Next Step.
4. CHECK HARNESS AND CONNECTOR NG : REPAIR OR REPLACE HARNESS OR CONNECTOR OK : CHECK AND REPLACE ECM

See also:
• CUSTOMER PROBLEM ANALYSIS CHECK
• DIAGNOSTIC TROUBLE CODE CHART