Air Conditioning (Diagnostic Codes & Circuit Tests): Overview Lexus GS III facelift

Scheme 195

Scheme 196

1. ACTUATOR CHECK Turn the engine switch on (IG) while pressing the A/C control AUTO switch and Recirculation / Fresh switch simultaneously. Press the Recirculation / Fresh switch. As each damper, motor and relay automatically operate the actuator check at 1 second intervals from step No. 1 to No. 10 continuously, check the temperature and airflow visually and by hand. If a slower display is desired, press the driver temperature up switch and change the display in the step operation. Each time the driver temperature up switch is pressed, the display changes by 1 step. HINT: The buzzer sounds when the displayed trouble code changes. Codes are displayed from smaller to larger numbers in order. To cancel the check mode, press the "OFF" switch. Step No. Display Code Conditions Blower Level Air Mix Damper Airflow Vent Air Inlet Damper Cool Air Bypass Damper Compressor 1 0 0 0% open FACE FRESH -14% OFF 2 1 1 0% open FACE FRESH -14% OFF 3 2 17 0% open FACE RECIRCULATION / FRESH -14% ON 4 3 17 0% open FACE RECIRCULATION 113.50% ON 5 4 17 50% open B/L RECIRCULATION 113.50% ON 6 5 17 50% open B/L RECIRCULATION 113.50% ON 7 6 17 50% open FOOT FRESH 113.50% ON 8 7 17 100% open FOOT-0 FRESH 113.50% ON 9 8 17 100% open F/D FRESH 113.50% ON 10 9 31 100% open DEF FRESH 113.50% ON

DESCRIPTION

The room temperature sensor is installed in the instrument panel to detect the room temperature and control the heater and air conditioner "AUTO" mode. The resistance of the room temperature sensor changes in accordance with the room temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The A/C amplifier applies voltage (5 V) to the room temperature sensor and reads voltage changes as the resistance of the room temperature sensor changes. This sensor also sends the appropriate signals to the A/C amplifier. The room temperature sensor is integrated with the room humidity sensor.

Scheme 197

Scheme 198

Scheme 199

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Room Temperature Sensor (Room Temp) Room temperature sensor / Min.: -6.5°C (20.3°F) Max.: 57.25°C (135.05°F) Actual room temperature is displayed Open in circuit: -6.5°C (20.3°F) Short in circuit: 57.25°C (135.05°F) OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
2. INSPECT ROOM TEMPERATURE SENSOR Remove the room temperature sensor. Measure the resistance of the sensor. Standard resistance Tester Connection Condition Specified Condition 1 (+) - 2 (-) 10°C (50°F) 3.00 to 3.73 kohms 1 (+) - 2 (-) 15°C (59°F) 2.45 to 2.88 kohms 1 (+) - 2 (-) 20°C (68°F) 1.95 to 2.30 kohms 1 (+) - 2 (-) 25°C (77°F) 1.60 to 1.80 kohms 1 (+) - 2 (-) 30°C (86°F) 1.28 to 1.47 kohms 1 (+) - 2 (-) 35°C (95°F) 1.00 to 1.22 kohms 1 (+) - 2 (-) 40°C (104°F) 0.80 to 1.00 kohms 1 (+) - 2 (-) 45°C (113°F) 0.65 to 0.85 kohms 1 (+) - 2 (-) 50°C (122°F) 0.50 to 0.70 kohms 1 (+) - 2 (-) 55°C (131°F) 0.44 to 0.60 kohms 1 (+) - 2 (-) 60°C (140°F) 0.36 to 0.50 kohms NOTE: Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor. When measuring, the sensor temperature must be the same as the ambient temperature. HINT: As the temperature increases, the resistance decreases (see the graph). NG --> REPLACE ROOM TEMPERATURE SENSOR OK: Go to next step
3. CHECK WIRE HARNESS (ROOM TEMPERATURE SENSOR - A/C AMPLIFIER) Disconnect the K33 room temperature sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition K33-1 (+) - K52-16 (TR) Always Below 1 ohms K33-2 (-) - K52-19 (SG-1) Always Below 1 ohms K52-16 (TR) - Body ground Always 10 kohms or higher K52-19 (SG-1) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

1. 2GR-FSE: The ambient temperature sensor is installed in the front part of the condenser to detect the ambient temperature and control the air conditioner "AUTO" mode. The sensor connected to the ECM detects fluctuations in the ambient temperature. This data is used for controlling the room temperature. The sensor sends a signal to the A/C amplifier via the ECM. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases. The ECM applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes. The ECM sends the read signal to the A/C amplifier via CAN and body multiplex communications.
2. 1UR-FSE: The ambient temperature sensor is installed in front of the condenser to detect the ambient temperature which is used to control the air conditioner "AUTO" mode. This sensor is connected to the A/C amplifier and detects fluctuations in the ambient temperature. This data is used for controlling the cabin temperature. The sensor sends a signal to the A/C amplifier. The resistance of the ambient temperature sensor changes in accordance with the ambient temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases. The A/C amplifier applies voltage (5 V) to the ambient temperature sensor and reads voltage changes as the resistance of the ambient temperature sensor changes. DTC No. DTC Detection Condition Trouble Area B1412/12 Open or short in ambient temperature sensor circuit 2GR-FSE: Ambient temperature sensor Harness and connector between ambient temperature sensor and ECM ECM Multiplex communication system (BEAN) CAN communication system A/C amplifier 1UR-FSE: Ambient temperature sensor Harness and connector between ambient temperature sensor and A/C amplifier A/C amplifier

Scheme 200

Scheme 201

1. 2GR-FSE
2. 1UR-FSE

The evaporator temperature sensor (A/C thermistor) is installed on the evaporator in the air conditioner unit to detect the cooled air temperature that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the A/C amplifier. The resistance of the evaporator temperature sensor (A/C thermistor) changes in accordance with the cooled air temperature that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The A/C amplifier applies voltage (5 V) to the evaporator temperature sensor (A/C thermistor) and reads voltage changes as the resistance of the evaporator temperature sensor (A/C thermistor) changes. This sensor is used for frost prevention.

Scheme 202

Scheme 203

Scheme 204

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Evaporator Temp Sensor (Evap Temp) Evaporator temperature sensor / Min.: -29.7°C (-21.46°F) Max.: 59.55°C (139.019°F) Actual evaporator temperature is displayed Open in circuit: -29.7°C (-21.46°F) Short in circuit: 59.55°C (139.19°F) OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE B --> REPLACE AIR CONDITIONING AMPLIFIER A: Go to next step
2. INSPECT EVAPORATOR TEMPERATURE SENSOR Disconnect the evaporator temperature sensor connector. Measure the resistance of the harness. Standard resistance Tester Connection Condition Specified Condition z9-1 - z9-2 -10°C (14°F) 7.30 to 9.10 kohms z9-1 - z9-2 -5°C (23°F) 5.65 to 6.95 kohms z9-1 - z9-2 0°C (32°F) 4.40 to 5.35 kohms z9-1 - z9-2 5°C (41°F) 3.40 to 4.15 kohms z9-1 - z9-2 10°C (50°F) 2.70 to 3.25 kohms z9-1 - z9-2 15°C (59°F) 2.14 to 2.58 kohms z9-1 - z9-2 20°C (68°F) 1.71 to 2.05 kohms z9-1 - z9-2 25°C (77°F) 1.38 to 1.64 kohms z9-1 - z9-2 30°C (86°F) 1.11 to 1.32 kohms NOTE: Even slightly touching the sensor may change the resistance value. Be sure to hold the connector of the sensor. When measuring, the sensor temperature must be the same as the ambient temperature. HINT: As the temperature increases, the resistance decreases (see the graph). NG --> REPLACE EVAPORATOR TEMPERATURE SENSOR OK: Go to next step
3. INSPECT AIR CONDITIONING HARNESS (A/C AMPLIFIER - EVAPORATOR TEMPERATURE SENSOR) Remove the air conditioning harness. Disconnect the A/C amplifier connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition z1-6 (TE) - z9-2 Always Below 1 ohms z1-5 (SG) - z9-1 Always Below 1 ohms z1-6 (TE) - Body ground Always 10 kohms or higher z1-5 (SG) - Body ground Always 10 kohms or higher NG --> REPLACE AIR CONDITIONING HARNESS OK --> REPLACE AIR CONDITIONING AMPLIFIER

The exhaust gas sensor, which is installed on the front of the condenser, automatically changes to FRESH, FRESH / RECIRCULATION, or RECIRCULATION. The exhaust gas sensor detects CO and HC in the emission gas and transmits signals to the A/C amplifier.

Scheme 205

Scheme 206

Scheme 207

Scheme 208

Scheme 209

1. INSPECT FUSE (LH-IG) Remove the LH-IG fuse from the cowl side junction block LH. Measure the resistance of the fuse. Standard resistance Tester Item Condition Specified Condition LH-IG fuse Always Below 1 ohms NG --> CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE OK: Go to next step
2. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Emission Gas Sensor (Emiss Gas Sens) Emission gas / Min.: 0, Max.: 255 Increases as the gas amount increases - OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
3. CHECK WIRE HARNESS (EXHAUST GAS SENSOR - BODY GROUND) Disconnect the B10 exhaust gas sensor connector. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Condition Specified Condition B10-6 (GND) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
4. CHECK WIRE HARNESS (EXHAUST GAS SENSOR - BATTERY) Disconnect the B10 exhaust gas sensor connector. Measure the voltage of the wire harness side connector. Standard voltage Tester Connection Condition Specified Condition B10-3 (IG) - Body ground Engine switch on (IG) 10 to 14 V Engine switch off Below 1 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. INSPECT EXHAUST GAS SENSOR Remove the exhaust gas sensor. After applying battery voltage between terminals 3 (IG) and 6 (GND) for more than 30 seconds, measure the resistance between terminals 1 (SG) and 2 (DGS). Measure the resistance of the sensor. Standard resistance Tester Connection Condition Specified Condition 1 (SG) - 2 (DGS) 10 to 35°C (50 to 95°F) 5 to 100 kohms HINT: When the sensor is exposed to the exhaust gas, the resistance increases. NG --> REPLACE EXHAUST GAS SENSOR OK: Go to next step
6. CHECK WIRE HARNESS (EXHAUST GAS SENSOR - A/C AMPLIFIER) Disconnect the B10 exhaust gas sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition B10-1 (SG) - K52-39 (SG-6) Always Below 1 ohms B10-2 (DGS) - K52-34 (DGS) Always Below 1 ohms K52-39 (SG-6) - Body ground Always 10 kohms or higher K52-34 (DGS) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

Scheme 210

The solar sensor, which is installed on the upper side of the instrument panel, detects sunlight and controls the air conditioning in AUTO mode. The output voltage from the solar sensor varies according to the amount of sunlight. When the sunlight increases, the output voltage increases. As the sunlight decreases, the output voltage decreases. The A/C amplifier detects output voltage from the solar sensor.

HINT

If DTC B1224 is output at the same time, troubleshoot DTC B1224 first.

Scheme 211

Scheme 212

Scheme 213

Scheme 214

Scheme 215

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measure Item/Range Normal Condition Diagnostic Note Solar Sensor (P Side) (Solar Sens-P) Passenger side solar sensor / Min.: 0, Max.: 255 Passenger side solar sensor voltage increases as brightness increases - OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
2. INSPECT MULTIPLEX NETWORK BODY ECU Remove the cowl side junction block RH with its connectors still connected. Measure the resistance of the multiplex network body ECU. Standard resistance Tester Connection Condition Specified Condition 4 (CLTE) - Body ground Always Below 1 ohms Measure the voltage of the multiplex network body ECU. Standard voltage Tester Connection Condition Specified Condition 6 (CLTB) - 4 (CLTE) Engine switch on (IG) 10 to 14 V Engine switch off Below 1 V NG --> REPLACE MULTIPLEX NETWORK BODY ECU OK: Go to next step
3. CHECK WIRE HARNESS (SOLAR SENSOR - MULTIPLEX NETWORK BODY ECU) Disconnect the L1 solar sensor connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition L1-3 (CLTE) - Body ground Always Below 1 ohms L1-6 (CLTB) - L1-3 (CLTE) Engine switch off Below 1 ohms Measure the voltage of the wire harness side connectors. Standard voltage Tester Connection Condition Specified Condition L1-6 (CLTB) - L1-3 (CLTE) Engine switch on (IG) 10 to 14 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
4. CHECK WIRE HARNESS (SOLAR SENSOR - A/C AMPLIFIER) Disconnect the L1 solar sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition K52-14 (TSP) - L1-2 (TSR) Always Below 1 ohms K52-14 (TSP) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. CHECK SOLAR SENSOR Remove the solar sensor with its connector still connected. Apply battery voltage between terminals 6 (CLTB) and 3 (CLTE) of the solar sensor. Measure the voltage of the sensor. Standard voltage Tester Connection Condition Specified Condition 2 (TSR) - 3 (CLTE) Sensor is subjected to electric light 0.8 to 4.3 V Sensor is covered with a cloth Below 0.8 V NOTE: As the inspection light is moved away from the sensor, the voltage increases. Use an incandescent light for inspection. Bring it about 30 cm (11.8 in.) from the solar sensor. NG --> REPLACE SOLAR SENSOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

This sensor sends 1 pulse per engine revolution to the ECM.

If the ratio between engine and compressor speed deviates 20% or more compared to normal operation, the ECM turns the cooler compressor off and the indicator blinks at approximately 1 second intervals.

The ECM informs the A/C amplifier of the operation condition of the cooler compressor through multiplex communication (CAN and BEAN).

Scheme 216

Scheme 217

Scheme 218

Scheme 219

1. INSPECT ECM Remove the ECM with its connectors still connected. Measure the waveform of the connector. Standard voltage Tester Connection Condition Specified Condition E8-10 (LCKI) - Body ground Engine switch on (IG) AUTO switch ON A/C switch ON Magnetic clutch ON Pulse generation Item Contents Tool setting 200 mV / DIV., 10 ms / DIV. Vehicle condition Engine switch on (IG) AUTO switch ON A/C switch ON Magnetic clutch ON Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE ECM B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
2. INSPECT A/C COMPRESSOR (LOCK SENSOR) Disconnect the E46 A/C compressor connector. Measure the resistance of the sensor. Standard resistance Tester Connection Specified Condition 2 (SSR+) - 5 (SSR-) 400 ohms NG --> REPLACE A/C COMPRESSOR (LOCK SENSOR) OK: Go to next step
3. CHECK WIRE HARNESS (ECM - A/C COMPRESSOR) Disconnect the E46 A/C compressor connector. Disconnect the E8 ECU connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition E8-10 (LCKI) - E46-2 (SSR+) Always Below 1 ohms E46-5 (SSR-) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> REPLACE ECM

This DTC is output when refrigerant pressure is extremely low (0.19 MPa (2.0 kgf/cm 2 , 28 psi) or less) or extremely high (3.14 MPa (32.0 kgf/cm 2 , 455 psi) or more). The pressure sensor, which is installed on the pipe of the high pressure side to detect refrigerant pressure, outputs the refrigerant pressure signal to the A/C amplifier. The A/C amplifier converts the signals to pressure according to the sensor characteristics to control the compressor.

HINT

Be sure to check the refrigerant volume first when this DTC is output because this DTC can also be output if there is no refrigerant in the cycle.

Scheme 220

Scheme 221

Scheme 222

Scheme 223

Scheme 224

1. CHECK REFRIGERANT Check the sight glass of the cooler unit refrigerant liquid pipe. Prepare the vehicle according to the chart below. Item Condition Vehicle Doors Fully open Temperature Setting MAX COLD Blower Speed HI A/C ON Compare the sight glass to the following chart. Item Symptom Amount of Refrigerant Corrective Actions 1 Bubbles visible Insufficient* Check for gas leakage and repair if necessary Add refrigerant until bubbles disappear 2 No bubbles visible Empty, insufficient or excessive Refer to 3 and 4 3 No temperature difference between compressor inlet and outlet Empty or nearly empty Check for gas leakage with gas leak detector and repair if necessary Evacuate A/C system and recharge proper amount of refrigerant 4 Considerable temperature difference between compressor inlet and outlet Proper or excessive Refer to 5 and 6 5 Immediately after air conditioning is turned OFF, refrigerant clears Excessive Discharge refrigerant Evacuate A/C system and recharge proper amount of refrigerant 6 Immediately after air conditioning is turned OFF, refrigerant foams and then becomes clear Proper - * : Bubbles in the sight glass with the vehicle interior above 35°C (95°F) can be considered normal if cooling is sufficient. NG --> CHARGE REFRIGERANT OK: Go to next step
2. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Regulator Pressure Sensor (Reg Press Sens) Regulator Pressure Sensor / Min.: -0.45668 MPaG, Max.: 3.29437 MPaG Actual regulator pressure is displayed - Regulator Control Current (Reg Ctrl Currnt) Regulator Control Current / Min.: 0 A, Max.: 255 A - - OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
3. CHECK WIRE HARNESS (PRESSURE SENSOR - A/C AMPLIFIER) Disconnect the B4 pressure sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition B4-2 (PR) - K52-13 (PRE) Always Below 1 ohms B4-3 (+) - K52-26 (S5-2) Always Below 1 ohms B4-1 (-) - K52-38 (SG-2) Always Below 1 ohms K52-13 (PRE) - Body ground Always 10 kohms or higher K52-26 (S5-2) - Body ground Always 10 kohms or higher K52-38 (SG-2) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
4. CHECK AIR CONDITIONING AMPLIFIER Remove the A/C amplifier with its connectors still connected. Measure the resistance of the connector. Standard resistance Tester Connection Condition Specified Condition K52-38 (SG-2) - Body ground Always Below 1 ohms Measure the voltage resistance of the connector. Standard voltage Tester Connection Condition Specified Condition K52-26 (S5-2) - Body ground Engine switch on (IG) 10 to 14 V Engine switch off Below 1 V NG --> REPLACE AIR CONDITIONING AMPLIFIER OK: Go to next step
5. INSPECT PRESSURE SENSOR Install the manifold gauge set. Connect the three 1.5 V dry cell batteries' positive (+) lead to terminal 3 and the negative (-) lead to terminal 1. Then connect the voltmeter's positive (+) lead to terminal 2and the negative (-) lead to terminal 1. Measure the voltage. OK The voltage changes according to refrigerant pressure, as shown in the graph. NG --> REPLACE PRESSURE SENSOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

The solar sensor, which is installed on the upper side of the instrument panel, detects sunlight and controls the air conditioning in AUTO mode. The output voltage from the solar sensor varies according to the amount of sunlight. When the sunlight increases, the output voltage increases. As the sunlight decreases, the output voltage decreases. The A/C amplifier detects output voltage from the solar sensor.

HINT

If DTC B1244 is output at the same time, troubleshoot DTC B1244 first.

Scheme 225

Scheme 226

Scheme 227

Scheme 228

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Solar Sensor (D Side) (Solar Sens-D) Driver side solar sensor / Min.: 0, Max.: 255 Driver side solar sensor voltage increases as brightness increases - OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
2. INSPECT MULTIPLEX NETWORK BODY ECU Remove the cowl side junction block RH with its connectors still connected. Measure the resistance of the connector. Standard resistance Tester Connection Condition Specified Condition 4 (CLTE) - Body ground Always Below 1 ohms Measure the voltage of the connector. Standard voltage Tester Connection Condition Specified Condition 6 (CLTB) - 4 (CLTE) Engine switch off Below 1 V Engine switch on (IG) 10 to 14 V NG --> REPLACE MULTIPLEX NETWORK BODY ECU OK: Go to next step
3. CHECK WIRE HARNESS (SOLAR SENSOR - MULTIPLEX NETWORK BODY ECU) Disconnect the L1 solar sensor connector. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Condition Specified Condition L1-3 (CLTE) - Body ground Always Below 1 ohms Measure the voltage of the wire harness side connector. Standard voltage Tester Connection Condition Specified Condition L1-6 (CLTB) - L1-3 (CLTE) Engine switch on (IG) 10 to 14 V Engine switch off Below 1 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
4. CHECK WIRE HARNESS (SOLAR SENSOR - A/C AMPLIFIER) Disconnect the L1 solar sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition K52-35 (TSD) - L1-1 (TSL) Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. CHECK SOLAR SENSOR Remove the solar sensor with its connector still connected. Apply battery voltage between terminals 6 (CLTB) and 3 (CLTE) of the solar sensor. Measure the voltage of the connector. Standard voltage Tester Connection Condition Specified Condition 1 (TSL) - 3 (CLTE) Sensor is subjected to electric light 0.8 to 4.3 V 1 (TSL) - 3 (CLTE) Sensor is covered with a cloth Below 0.8 V NOTE: As the inspection light is moved away from the sensor, the voltage increases. Use an incandescent light for inspection. Bring it about 30 cm (11.8 in.) from the solar sensor. NG --> REPLACE SOLAR SENSOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

The air mix damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the air mix damper (passenger seat) to any position, which adjusts the amount of air passing the heater core after passing the evaporator to control the blowing temperature.

HINT

Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

Scheme 229

The damper servo (air inlet control) sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the air inlet mode selection air inlet control damper to any position, which controls the intake air settings (FRESH, FRESH / RECIRCULATION and RECIRCULATION).

HINT

Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

Scheme 230

The mode damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the mode damper to any position, which controls the air outlet changes.

HINT

Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

Scheme 231

The damper servo (cool air by-pass) sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the damper to any position. As a result, when the A/C is operating, the temperature of the air blowing toward the passenger's head area is controlled.

HINT

Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

Scheme 232

The air mix damper servo sends pulse signals to inform the air conditioner amplifier of the damper position. The air conditioner amplifier activates the motor (normal, reverse) based on the signals to move the air mix damper (driver seat) to any position. As a result, the amount of air that has passed through the evaporator and is now passing through the heater core is adjusted, and the temperature of the air blowing toward the driver seat side is controlled.

HINT

Confirm that no mechanical problem is present because this diagnostic code can be output when either a damper link or damper is mechanically locked.

Scheme 233

In this circuit, the compressor receives a refrigerant compression demand signal from the air conditioning amplifier.

Based on this signal, the compressor changes the degree of refrigerant compression.

Scheme 234

Scheme 235

Scheme 236

Scheme 237

Scheme 238

Scheme 239

1. INSPECT A/C COMPRESSOR 2GR-FSE Disconnect the E46 A/C compressor connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition E46-3 (SOL+) - E46-6 (SOL-) 20°C (68°F) 10 to 11 ohms 1UR-FSE Disconnect the E1 A/C compressor connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition E1-2 (SOL+) - E1-1 (SOL-) 20°C (68°F) 10 to 11 ohms NG --> REPLACE A/C COMPRESSOR OK: Go to next step
2. CHECK HARNESS AND CONNECTOR (A/C COMPRESSOR - BODY GROUND) 2GR-FSE Disconnect the E46 A/C compressor connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition E46-6 (SOL-) - Body ground Always Below 1 ohms 1UR-FSE Disconnect the E1 A/C compressor connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition E1-1 (SOL-) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (A/C COMPRESSOR - A/C AMPLIFIER) Disconnect the E46 or E1 A/C compressor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition K52-5 (SOL+) - E46-3 (SOL+) *1 Always Below 1 ohms K52-5 (SOL+) - E1-2 (SOL+) *2 Always Below 1 ohms HINT: *1: 2GR-FSE *2: 1UR-FSE Result Result Proceed to NG A OK (When troubleshooting according to the PROBLEM SYMPTOMS TABLE) B OK (When troubleshooting according to the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A --> REPAIR OR REPLACE HARNESS AND CONNECTOR

The exhaust gas sensor detects NOx in the emission gas and transmits signals to the A/C amplifier. Based on the signals, the A/C amplifier automatically changes to FRESH, FRESH / RECIRCULATION, or RECIRCULATION.

Scheme 240

Scheme 241

1. INSPECT FUSE (LH-IG) Remove the LH-IG fuse from the cowl side junction block LH. Measure the resistance of the fuse. Standard resistance Tester Item Condition Specified Condition LH-IG fuse Always Below 1 ohms NG --> CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE OK: Go to next step
2. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Emission Gas Nox Sensor (Nox Gas Sens) Emission gas NOx sensor / Min.: 0, Max.: 255 Increases as gas amount increases - OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
3. CHECK WIRE HARNESS (EXHAUST GAS SENSOR - BODY GROUND) Disconnect the B10 exhaust gas sensor connector. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Condition Specified Condition B10-6 (GND) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
4. CHECK WIRE HARNESS (EXHAUST GAS SENSOR - BATTERY) Disconnect the B10 exhaust gas sensor connector. Measure the voltage of the wire harness side connector. Standard voltage Tester Connection Condition Specified Condition B10-3 (IG) - Body ground Engine switch on (IG) 10 to 14 V Engine switch off Below 1 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. INSPECT EXHAUST GAS SENSOR Remove the exhaust gas sensor. After applying battery voltage between terminals 3 (IG) and 6 (GND) for more than 120 seconds, measure the resistance between terminals 1 (SG) and 4 (DGS1). Measure the resistance of the sensor. Standard resistance Tester Connection Condition Specified Condition B10-1 (SG) - B10-4 (DGS1) 10 to 35°C (50 to 95°F) 5 to 100 kohms HINT: When the sensor is exposed to the exhaust gas, the resistance increases. NG --> REPLACE EXHAUST GAS SENSOR OK: Go to next step
6. CHECK WIRE HARNESS (EXHAUST GAS SENSOR - A/C AMPLIFIER) Disconnect the B10 exhaust gas sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition B10-1 (SG) - K52-39 (SG-6) Always Below 1 ohms B10-4 (DGS1) - K52-33 (DGS1) Always Below 1 ohms K52-39 (SG-6) - Body ground Always Below 1 ohms K52-33 (DGS1) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

The room humidity sensor detects room humidity. The voltage of the room humidity sensor changes in accordance with room humidity. The A/C amplifier reads changes in the room humidity sensor.

The room humidity sensor is integrated with the room temperature sensor.

Scheme 242

Scheme 243

Scheme 244

1. READ VALUE USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Data List, and read the display on the Techstream. Data List / Air Conditioner: Tester Display Measurement Item/Range Normal Condition Diagnostic Note Humidity Sensor (Humidity Sens) Humidity Sensor / Min.: 0%, Max.: 100% Actual room humidity is displayed - OK The display is as specified in the normal condition. Result: NG A OK (Checking from the PROBLEM SYMPTOMS TABLE) B OK (Checking from the DTC) C C --> REPLACE AIR CONDITIONING AMPLIFIER B --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE A: Go to next step
2. CHECK WIRE HARNESS (ROOM TEMPERATURE SENSOR - A/C AMPLIFIER) Disconnect the K33 room temperature sensor connector. Disconnect the K52 A/C amplifier connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Condition Specified Condition K33-3 (RH) - K52-15 (RH) Always Below 1 ohms K33-4 (S5) - K52-7 (S5-1) Always Below 1 ohms K33-2 (-) - K52-19 (SG-1) Always Below 1 ohms K52-19 (SG-1) - Body ground Always 10 kohms or higher K52-15 (RH) - Body ground Always Below 1 ohms K52-7 (S5-1) - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
3. CHECK AIR CONDITIONING AMPLIFIER Remove the A/C amplifier with its connectors still connected. Measure the voltage of the connector. Standard voltage Tester Connection Condition Specified Condition K52-7 (S5-1) - K52-19 (SG-1) Engine switch on (IG) 4.5 to 5.5 V NG --> REPLACE AIR CONDITIONING AMPLIFIER OK: Go to next step
4. CHECK ROOM HUMIDITY SENSOR Remove the room temperature sensor. Measure the voltage of the sensor. Standard voltage Tester Connection Condition Specified Condition 2 (-) - 3 (RH) 10% 0.70 to 1.08 V 2 (-) - 3 (RH) 20% 0.72 to 1.57 V 2 (-) - 3 (RH) 30% 1.13 to 1.95 V 2 (-) - 3 (RH) 40% 1.61 to 2.24 V 2 (-) - 3 (RH) 50% 1.99 to 2.46 V 2 (-) - 3 (RH) 60% 2.26 to 2.66 V 2 (-) - 3 (RH) 70% 2.48 to 2.85 V 2 (-) - 3 (RH) 80% 2.68 to 3.04 V 2 (-) - 3 (RH) 90% 2.87 to 3.05 V NOTE: Do not touch the humidity sensor as body heat will affect the inspection results. When performing the inspection, hold the sensor by its connector. Allow the sensor to acclimate to the ambient temperature and humidity before performing the inspection. The standard voltages in the table above are based on inspections performed when the ambient temperature is 25°C (77°F). HINT: As the humidity increases, the resistance decreases (see the graph). NG --> REPLACE ROOM HUMIDITY SENSOR OK --> REPLACE AIR CONDITIONING AMPLIFIER

The air conditioning harness connects the air conditioning amplifier and each servo. The air conditioning amplifier supplies power and sends operation instructions to each servo through the air conditioning harness. Each servo sends the damper position information to the air conditioning amplifier.

Scheme 245

Scheme 246

1. CHECK AIR CONDITIONING AMPLIFIER Remove the A/C amplifier with its connectors still connected. Measure the resistance of the connector. Standard resistance Tester Connection Condition Specified Condition z1-2 (BUSG) - Body ground Always Below 1 ohms NG --> REPLACE AIR CONDITIONING AMPLIFIER OK: Go to next step
2. CHECK AIR CONDITIONING AMPLIFIER Measure the voltage of the connector. Standard voltage Tester Connection Condition Specified Condition z1-2 (BUSG) - z1-4 (BBUS) Engine switch on (IG) 10 to 14 V Engine switch off Below 1 V NG --> REPLACE AIR CONDITIONING AMPLIFIER OK --> REPLACE AIR CONDITIONING HARNESS

Scheme 247

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

Duty Ratio

The duty ratio is the ratio of the blower motor ON time (A) to the total of the blower motor ON and OFF time (A + B).

The blower motor controller controls the blower motor speed.

Scheme 248

Scheme 249

Scheme 250

Scheme 251

Scheme 252

Scheme 253

1. PERFORM ACTIVE TEST USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Active Test and then check that the relay operates. Active Test / Air Conditioner: Tester Display Test Part Control Range Diagnostic Note Blower Motor (Blower Motor) Blower motor Min.: Level 0, Max.: Level 31 - Result: OK A NG (blower motor does not operate) B NG (blower motor operates but does not change speed) C C --> See step 6 B --> See step 2 A --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
2. INSPECT FUSE Remove the HEATER fuse and ALT fuse from the engine room No. 1 junction block. Measure the resistance of the fuse. Standard resistance Tester Item Condition Specified Condition HEATER fuse Always Below 1 ohms ALT fuse Always Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
3. CHECK WIRE HARNESS (BLOWER MOTOR - BODY GROUND) Disconnect the blower motor connector. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Condition Specified Condition k1-1 (GND) - Body ground Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
4. CHECK WIRE HARNESS (BLOWER MOTOR - BATTERY) Disconnect the blower motor connector. Measure the voltage of the wire harness side connector. Standard voltage Tester Connection Condition Specified Condition k1-3 (+B) - Body ground Always 10 to 14 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. INSPECT BLOWER MOTOR Disconnect the A/C amplifier connector. Connect the blower motor connector. Measure the voltage of the connector. Standard voltage Tester Connection Condition Specified Condition k1-2 (S1) - Body ground Engine switch on (IG) 4.5 to 5.5 V NG --> REPLACE BLOWER MOTOR OK: Go to next step
6. CHECK WIRE HARNESS (A/C AMPLIFIER - BODY GROUND) Disconnect the A/C amplifier connector. Measure the voltage of the wire harness side connector. Standard voltage Tester Connection Condition Specified Condition K52-11 (BLW) - Body ground Engine switch on (IG) 4.5 to 5.5 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
7. INSPECT AIR CONDITIONING AMPLIFIER Remove the A/C amplifier with its connectors still connected. Turn the engine switch on (IG). Turn the blower switch ON (Lo). Measure the waveform between terminal K52-11 (BLW) of the A/C amplifier and body ground. OK Waveform is as shown in the illustration. HINT: Waveform varies with the blower level. Item Contents Tool setting 2 V / DIV., 500 μs / DIV. Vehicle condition Engine switch on (IG) Blower switch ON (Lo) NG --> REPLACE AIR CONDITIONING AMPLIFIER OK --> REPLACE BLOWER MOTOR

The A/C amplifier sends a magnetic clutch ON command signal to the ECM through the BEAN line and CAN line. Then the ECM turns the A/C COMP relay on to turn the magnetic clutch on.

Scheme 254

Scheme 255

Scheme 256

Scheme 257

Scheme 258

1. INSPECT FUSE (A/C COMP) Remove the A/C COMP fuse from the engine room No. 2 relay block, junction block. Measure the resistance of the fuse. Standard resistance Tester Item Condition Specified Condition A/C COMP fuse Always Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
2. PERFORM ACTIVE TEST USING TECHSTREAM Connect the Techstream to the DLC3. Turn the engine switch on (IG). Turn the Techstream on. Select the item below in the Active Test and then check that the relay operates. Active Test / Engine and ECT: Tester Display Test Part Control Range Diagnostic Note A/C Magnetic Clutch Relay (A/C MAG CLUTCH) Magnetic Clutch Relay OFF, ON - OK --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE NG: Go to next step
3. INSPECT RELAY (A/C COMP) Remove the A/C COMP relay from the engine room No. 2 relay block. Measure the resistance of the relay. Standard resistance Tester Connection Specified Condition 3 - 5 10 kohms or higher 3 - 5 Below 1 ohms (when battery voltage is applied to terminals 1 and 2) NG --> REPLACE RELAY OK: Go to next step
4. INSPECT A/C COMPRESSOR Disconnect the E46 A/C compressor connector. Measure the resistance of the connector. Standard resistance Tester Connection Condition Specified Condition 1 (MG+) - Body ground Always Below 1 ohms When connector terminal 1 (MG+) is connected to the positive (+) battery terminal, and the body ground is connected to the negative (-) battery terminal, check that the following occurs: 1) the magnetic clutch's operating sound is emitted, and 2) the magnetic clutch's hub and rotor lock. NG --> REPLACE A/C COMPRESSOR OK: Go to next step
5. CHECK WIRE HARNESS (ENGINE ROOM NO. 2 RELAY BLOCK - A/C COMPRESSOR) Remove the A/C COMP relay from the engine room No. 2 relay block. Disconnect the E46 A/C compressor connector. Measure the resistance of the wire harness side connector. Standard resistance Tester Connection Specified Condition Relay block A/C COMP relay terminal 3 - E46-1 (MG+) Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
6. CHECK WIRE HARNESS (ENGINE ROOM NO. 2 RELAY BLOCK - ECM) Remove the A/C COMP relay from the engine room No. 2 relay block. Disconnect the A7 ECM connector. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition Relay block A/C COMP relay terminal 2 - A7-11 (ACMG) Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

The GLW RLY turns on when it receives a signal from the A/C amplifier. As a result, power is supplied to the heater glow plug.

Scheme 259

Scheme 260

Scheme 261

Scheme 262

Scheme 263

Scheme 264

Scheme 265

1. INSPECT FUSE (ECU-IG LH, GLW PLG1, GLW PLG2) Remove the ECU-IG LH fuse from the cowl side junction block LH. Remove the GLW PLG1 and GLW PLG2 H-fuse from the engine room No. 1 junction block. Measure the resistance of the fuses. Standard resistance Tester Item Condition Specified Condition ECU-IG LH fuse Always Below 1 ohms GLW PLG1 H-fuse Always Below 1 ohms GLW PLG2 H-fuse Always Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
2. CHECK AIR CONDITIONING AMPLIFIER Remove the A/C amplifier with its connectors still connected. Turn the engine switch on (IG). While the PTC operating conditions are met (engine is running at 850 rpm or more, ambient temperature is 3°C (37.4°F) or less, engine coolant temperature is 75°C (167°F) or less, A/C switch setting is MAX HOT), turn the blower switch to the Lo setting. Measure the voltage of the connectors. Standard voltage Tester Connection Specified Condition K52-2 (HTR2) - Body ground 10 to 14 V K51-13 (HTR1) - Body ground 10 to 14 V OK --> REPLACE PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE NG: Go to next step
3. INSPECT RELAY (GLW RLY1, GLW RLY2) Remove the GLW RLY1 and GLW RLY2 relays from the engine room No. 4 relay block. Measure the resistance of the relays. Standard resistance Tester Connection Specified Condition 3 - 5 10 kohms or higher 3 - 5 Below 1 ohms (when battery voltage is applied to terminals 1 and 2) NG --> REPLACE RELAY OK: Go to next step
4. CHECK WIRE HARNESS (A/C AMPLIFIER - ENGINE ROOM NO. 4 RELAY BLOCK) Disconnect the K51 and K52 A/C amplifier connector. Remove the GLW RLY1 and GLW RLY2 relays from the engine room No. 4 relay block. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition K52-2 (HTR2) - Relay block GLW RLY2 relay terminal 2 Below 1 ohms K51-13 (HTR1) - Relay block GLW RLY1 relay terminal 2 Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK: Go to next step
5. CHECK WATER BY-PASS GLOW PLUG Remove the glow plug. Measure the resistance of the glow plug. Standard resistance Below 1 ohms NG --> REPLACE WATER BY-PASS GLOW PLUG OK: Go to next step
6. INSPECT HEATER BLOWER WIRE Remove the heater blower wire. Measure the resistance of the heater blower wire. Standard resistance Tester Connection Condition Specified Condition E78-1 - f1-1 Always Below 1 ohms E78-1 - f2-1 Always 10 kohms or higher E78-2 - f2-1 Always Below 1 ohms E78-2 - f1-1 Always 10 kohms or higher NG --> REPLACE HEATER BLOWER WIRE OK: Go to next step
7. CHECK WIRE HARNESS (HEATER BLOWER WIRE - ENGINE ROOM NO. 4 RELAY BLOCK) Disconnect the E78 heater blower wire. Remove the GLW RLY1 and GLW RLY2 relays from the engine room No. 4 relay block. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition Relay block GLW RLY2 relay terminal 5 - E78-2 Below 1 ohms Relay block GLW RLY1 relay terminal 5 - E78-1 Below 1 ohms NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

The main power source is supplied to the A/C amplifier when the engine switch is on (IG).

The power source is used for operating the A/C amplifier and servomotor, etc.

Scheme 266

The back-up power source circuit for the A/C amplifier is shown below. Power is supplied even when turning the engine switch off and is used for diagnostic trouble code memory, etc.

Scheme 267

Scheme 268

1. INSPECT FUSE (A/C) Remove the A/C fuse from the cowl side junction block LH. Measure the resistance of the fuse. Standard resistance Tester Item Condition Specified Condition A/C fuse Always Below 1 ohms NG --> CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE OK: Go to next step
2. INSPECT AIR CONDITIONING AMPLIFIER (AIR CONDITIONING AMPLIFIER - BODY GROUND) Disconnect the K52 A/C amplifier connector. Measure the voltage of the wire harness side connector. Standard voltage Tester Connection Condition Specified Condition K52-1 (B) - Body ground Always 10 to 14 V NG --> REPAIR OR REPLACE HARNESS AND CONNECTOR OK --> PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE