Air Conditioning System (Automatic) (Diagnostic Codes & Circuit Tests): Overview Toyota 4Runner V

DESCRIPTION

The cooler thermistor (room temperature sensor) for the front seat 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 front room temperature. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly 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 air conditioning amplifier assembly.

Scheme 191

Scheme 192

1. READ VALUE USING TECHSTREAM (ROOM TEMPERATURE SENSOR) Use the Data List to check if the cooler thermistor (room temperature sensor) is functioning properly. Refer to «DATA LIST / ACTIVE TEST»(ref-422144-S07427586662011092600000). AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Diagnostic Note Room Temperature Sensor Cooler thermistor (room temperature sensor) / Min.: -6.5°C (20.3°F) Max.: 57.25°C (135.05°F) Actual room temperature for front seat displayed Open in the circuit: -6.5°C (20.3°F). Short in the circuit: 57.25°C (135.05°F). OK The display is as specified in the normal condition column. RESULT Result Proceed to OK (When troubleshooting according to problem symptoms table) A OK (When troubleshooting according to the DTC) B NG C B --> See step 4 C --> See step 2 A --> See step 6
2. INSPECT COOLER THERMISTOR (ROOM TEMPERATURE SENSOR) Remove the cooler thermistor (room temperature sensor). Refer to «REMOVAL»(ref-422116-S42422915752011092600000). Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 - 2 10°C (50°F) 3.00 to 3.73 kohms 15°C (59°F) 2.45 to 2.88 kohms 20°C (68°F) 1.95 to 2.30 kohms 25°C (77°F) 1.60 to 1.80 kohms 30°C (86°F) 1.28 to 1.47 kohms 35°C (95°F) 1.00 to 1.22 kohms 40°C (104°F) 0.80 to 1.00 kohms 45°C (113°F) 0.65 to 0.85 kohms 50°C (122°F) 0.50 to 0.70 kohms 55°C (131°F) 0.44 to 0.60 kohms 60°C (140°F) 0.36 to 0.50 kohms TEXT IN ILLUSTRATION *a Sensing Portion *b Resistance *c Allowable Range *d Temperature 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 (refer to the graph (Scheme 192)). NG --> See step 5 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (ROOM TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER) Disconnect the F26 sensor connector. Disconnect the F42 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition F26-1 - F42-29 (TR) Always Below 1 ohms F26-2 - F42-34 (SG-1) F42-29 (TR) - Body ground Always 10 kohms or higher F42-34 (SG-1) - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 4
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(ref-422116-S31564571222011092600000)
5. REPLACE COOLER THERMISTOR (ROOM TEMPERATURE SENSOR). Refer to «REMOVAL»(ref-422116-S42422915752011092600000)
6. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-422144-S39567940892011092600000)

The cooler thermistor (ambient temperature sensor) is installed in the front part of the cooler condenser assembly to detect the ambient temperature and control the air conditioning auto mode. The sensor connected to the air conditioning amplifier assembly detects fluctuations in the ambient temperature. This data is used for controlling the room temperature. The sensor sends a signal to the air conditioning amplifier assembly. The resistance of the cooler thermistor (ambient temperature sensor) changes in accordance with the cooler thermistor temperature (ambient temperature). As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies a voltage (5 V) to the cooler thermistor (ambient temperature sensor) and reads voltage changes as changes in the resistance of the cooler thermistor (ambient temperature sensor).

Scheme 193

Scheme 194

1. READ VALUE USING TECHSTREAM (AMBIENT TEMPERATURE SENSOR) Use the Data List to check if the cooler thermistor (ambient temperature sensor) is functioning properly. Refer to «DATA LIST / ACTIVE TEST»(ref-422144-S07427586662011092600000). AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Diagnostic Note Ambient Temp Sensor Cooler thermistor (ambient temperature sensor) / Min: -23.3°C (-9.94°F) Max: 65.95°C (150.71°F) Actual ambient temperature displayed Open in the circuit: -23.3°C (-9.94°F). Short in the circuit: 65.95°C (150.71°F). OK The display is as specified in the normal condition column. RESULT Result Proceed to OK (When troubleshooting according to problem symptoms table) A OK (When troubleshooting according to the DTC) B NG C B --> See step 4 C --> See step 2 A --> See step 7
2. INSPECT COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR) Remove the cooler thermistor (ambient temperature sensor). Refer to «REMOVAL»(ref-422116-S39470921182011092600000). Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 - 2 10°C (50°F) 3.00 to 3.73 kohms 15°C (59°F) 2.45 to 2.88 kohms 20°C (68°F) 1.95 to 2.30 kohms 25°C (77°F) 1.60 to 1.80 kohms 30°C (86°F) 1.28 to 1.47 kohms 35°C (95°F) 1.00 to 1.22 kohms 40°C (104°F) 0.80 to 1.00 kohms 45°C (113°F) 0.65 to 0.85 kohms 50°C (122°F) 0.50 to 0.70 kohms 55°C (131°F) 0.44 to 0.60 kohms 60°C (140°F) 0.36 to 0.50 kohms TEXT IN ILLUSTRATION *a Sensing Portion *b Resistance *c Allowable Range *d Temperature 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 (refer to the graph (Scheme 194)). NG --> See step 5 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (AMBIENT TEMPERATURE SENSOR - AIR CONDITIONING AMPLIFIER) Disconnect the A23 sensor connector. Disconnect the F42 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition A23-1 - F42-5 (TAM) Always Below 1 ohms A23-2 - F42-13 (SG-2) F42-5 (TAM) - Body ground Always 10 kohms or higher F42-13 (SG-2) - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 6
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(ref-422116-S31564571222011092600000)
5. REPLACE COOLER THERMISTOR (AMBIENT TEMPERATURE SENSOR). Refer to «REMOVAL»(ref-422116-S39470921182011092600000)
6. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(ref-422116-S31564571222011092600000)
7. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-422144-S39567940892011092600000)

The No. 1 cooler thermistor is installed on the evaporator in the air conditioning unit to detect the temperature of the cooled air that has passed through the evaporator and control the air conditioning. It sends appropriate signals to the air conditioning amplifier assembly. The resistance of the No. 1 cooler thermistor changes in accordance with the temperature of the cooled air that has passed through the evaporator. As the temperature decreases, the resistance increases. As the temperature increases, the resistance decreases.

The air conditioning amplifier assembly applies voltage (5 V) to the No. 1 cooler thermistor and reads voltage changes as the resistance of the No. 1 cooler thermistor changes. This sensor is used for frost prevention.

Scheme 195

Scheme 196

Scheme 197

1. READ VALUE USING TECHSTREAM (NO. 1 COOLER THERMISTOR) Use the Data List to check if the No. 1 cooler thermistor is functioning properly. Refer to «DATA LIST / ACTIVE TEST»(ref-422144-S07427586662011092600000). AIR CONDITIONER Tester Display Measurement Item/Range Normal Condition Diagnostic Note Evaporator Fin Thermistor No. 1 cooler thermistor / Min.: -29.7°C (-21.46°F) Max.: 59.55°C (139.19°F) Actual evaporator temperature displayed Open in the circuit: -29.7°C (-21.46°F). Short in the circuit: 59.55°C (139.19°F). OK The display is as specified in the normal condition column. RESULT Result Proceed to OK (When troubleshooting according to problem symptoms table) A OK (When troubleshooting according to the DTC) B NG C B --> See step 4 C --> See step 2 A --> See step 7
2. INSPECT NO. 1 COOLER THERMISTOR Remove the No. 1 cooler thermistor. Refer to «REMOVAL»(ref-422116-S17401372922011092600000). Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 - 2 -10°C (14°F) 7.30 to 9.10 kohms -5°C (23°F) 5.65 to 6.95 kohms 0°C (32°F) 4.40 to 5.35 kohms 5°C (41°F) 3.40 to 4.15 kohms 10°C (50°F) 2.70 to 3.25 kohms 15°C (59°F) 2.14 to 2.58 kohms 20°C (68°F) 1.71 to 2.05 kohms 25°C (77°F) 1.38 to 1.64 kohms 30°C (86°F) 1.11 to 1.32 kohms TEXT IN ILLUSTRATION *a Sensing Portion *b Resistance *c Allowable Range *d Temperature 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 (refer to the graph (Scheme 196)). NG --> See step 5 OK: Go to next step
3. INSPECT AIR CONDITIONING HARNESS ASSEMBLY Remove the air conditioning harness assembly. Refer to «DISASSEMBLY»(ref-422116-S38662320362011092600000). Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition z14-6 (TE) - 2 Always Below 1 ohms z14-5 (SG) - 1 Always Below 1 ohms z14-6 (TE) - Body ground Always 10 kohms or higher z14-5 (SG) - Body ground Always 10 kohms or higher TEXT IN ILLUSTRATION *a Front view of wire harness connector (to No. 1 Cooler Thermistor) *b Front view of wire harness connector (to Air Conditioning Amplifier Assembly) NG --> See step 6 OK --> See step 4
4. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(ref-422116-S31564571222011092600000)
5. REPLACE NO. 1 COOLER THERMISTOR. Refer to «REMOVAL»(ref-422116-S17401372922011092600000)
6. REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to «DISASSEMBLY»(ref-422116-S38662320362011092600000)
7. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-422144-S39567940892011092600000)

SYSTEM DESCRIPTION

The ECM sends the engine speed signal to the air conditioning amplifier assembly via CAN communication.

The air conditioning amplifier assembly reads the difference between compressor speed and engine speed. When the difference becomes too large, the air conditioning amplifier assembly determines that the cooler compressor assembly is locked and turns the magnet clutch assembly off.

Scheme 198

The damper servo sub-assembly (front passenger side air mix damper servo) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air mix damper (for front passenger side) to any position. As a result, the air mix damper (for front passenger side) varies the mixture of hot air from the heater core and cold air from the evaporator so that the temperature of the air blowing toward the front passenger side is as requested.

HINT

Confirm that no mechanical problem is present because this trouble code may be stored when either a damper link or damper is mechanically locked.

Scheme 199

The recirculation damper servo sub-assembly sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air inlet 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 trouble code may be stored when either a damper link or damper is mechanically locked.

Scheme 200

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

HINT

Confirm that no mechanical problem is present because this trouble code may be stored when either a damper link or damper is mechanically locked.

Scheme 201

The damper servo sub-assembly (driver side air mix damper servo) sends pulse signals to inform the air conditioning amplifier assembly of the damper position. The air conditioning amplifier assembly activates the motor (normal or reverse) based on the signals to move the air mix damper (for driver side) to any position. As a result, the air mix damper (for driver side) varies the mixture of hot air from the heater core and cold air from the evaporator so that the temperature of the air blowing toward the front passenger side is as requested.

HINT

Confirm that no mechanical problem is present because this trouble code may be stored when either a damper link or damper is mechanically locked.

Scheme 202

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

Scheme 203

Scheme 204

1. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY Remove the air conditioning amplifier assembly with its connectors still connected. Refer to «REMOVAL»(ref-422116-S31564571222011092600000) . Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition z14-2 (BUS G) - Body ground Always Below 1 ohms Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Switch Condition Specified Condition z14-2 (BUS G) - z14-4 (B BUS) Always 11 to 14 V z14-2 (BUS G) - z14-3 (BUS) Ignition switch ON Pulse generation TEXT IN ILLUSTRATION *a Component with harness connected (Air Conditioning Amplifier Assembly) RESULT Result Proceed to OK (When troubleshooting according to problem symptoms table) A OK (When troubleshooting according to the DTC) B NG C B --> See step 2 C --> See step 3 A --> See step 4
2. REPLACE AIR CONDITIONING HARNESS ASSEMBLY. Refer to «DISASSEMBLY»(ref-422116-S38662320362011092600000)
3. REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY. Refer to «REMOVAL»(ref-422116-S31564571222011092600000)
4. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-422144-S39567940892011092600000)

Scheme 205

The automatic light control sensor (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 current from the automatic light control sensor (solar sensor) varies according to the amount of sunlight. When the amount of sunlight increases, the output current increases. As the amount of sunlight decreases, the output current decreases. The air conditioning amplifier assembly detects the output current from the automatic light control sensor (solar sensor).

Scheme 206

The automatic light control sensor (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 current from the solar sensor varies according to the amount of sunlight. When the amount of sunlight increases, the output current increases. As the amount of sunlight decreases, the output current decreases. The air conditioning amplifier assembly detects the output current from the solar sensor.

Scheme 207

The air conditioning amplifier communicates with the ECM, main body ECU (multiplex network body ECU) and combination meter through the CAN communication system.

This circuit consists of the heater control assembly and air conditioning amplifier assembly. When the heater control assembly is operated, signals are transmitted to the air conditioning amplifier assembly through the LIN communication system.

If the LIN communication system malfunctions, the air conditioning amplifier assembly does not operate when the heater control assembly is operated.

Scheme 208

When the air conditioning amplifier assembly is turned on, a magnet clutch assembly signal is sent from the MGC terminal of the air conditioning amplifier assembly. Then, the A/C COMP relay turns on to operate the magnet clutch assembly.

Scheme 209

PTC heater relays are closed in accordance with signals from the air conditioning amplifier assembly and power is supplied to the quick heater assembly installed on the radiator heater unit.

Scheme 210

Scheme 211

Scheme 212

Scheme 213

Scheme 214

Scheme 215

Scheme 216

1. INSPECT PTC HEATER RELAY (PTC NO. 1, PTC NO. 2, PTC NO. 3) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block. Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 3 - 5 Battery voltage is not applied to terminals 1 and 2 10 kohms or higher Battery voltage is applied to terminals 1 and 2 Below 1 ohms NG --> REPLACE PTC HEATER RELAY (PTC NO. 1, PTC NO. 2, PTC NO. 3) OK: Go to next step
2. CHECK AIR CONDITIONING AMPLIFIER ASSEMBLY Remove the air conditioning amplifier assembly with its connectors still connected. Refer to «REMOVAL»(ref-422116-S31564571222011092600000) . Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition F42-3 (PTC1) - Body ground Engine running (1250 RPM or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch off Below 1 V* F42-22 (PTC2) - Body ground Engine running (1250 RPM or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch off F42-4 (PTC3) - Body ground Engine running (1250 RPM or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch off F42-3 (PTC1) - Body ground Engine running (1250 RPM or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 79°C (174°F) or less Headlight dimmer switch off Blower switch on 11 to 14 V* F42-22 (PTC2) - Body ground Engine running (1250 RPM or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 76°C (169°F) or less Headlight dimmer switch off Blower switch on F42-4 (PTC3) - Body ground Engine running (1250 RPM or more) Temperature setting MAX HOT Outside temperature 10°C (50°F) or less Engine coolant temperature 73°C (163°F) or less Headlight dimmer switch off Blower switch on TEXT IN ILLUSTRATION *a Component with harness connected (Air Conditioning Amplifier Assembly) HINT: *: After the measurement conditions are met, wait 30 seconds before performing measurements. NG --> See step 12 OK: Go to next step
3. CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK - AIR CONDITIONING AMPLIFIER) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block. Disconnect the F42 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 1 - F42-3 (PTC1) Always Below 1 ohms PTC NO. 1 relay terminal 1 - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
4. CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - AIR CONDITIONING AMPLIFIER) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block. Disconnect the F42 amplifier connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC NO. 2 relay terminal 1 - F42-22 (PTC2) Always Below 1 ohms PTC NO. 3 relay terminal 1 - F42-4 (PTC3) PTC NO. 2 relay terminal 1 - Body ground Always 10 kohms or higher PTC NO. 3 relay terminal 1 - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
5. CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK - QUICK HEATER) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block. Disconnect the F85 heater connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 3 - F85-2 (B) Always Below 1 ohms PTC NO. 1 relay terminal 3 - Body ground Always 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
6. CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - QUICK HEATER) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block. Disconnect the F85 heater connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC NO. 2 relay terminal 3 - F85-3 (B) Always Below 1 ohms PTC NO. 3 relay terminal 3 - F85-1 (B) PTC NO. 2 relay terminal 3 - Body ground Always 10 kohms or higher PTC NO. 3 relay terminal 3 - Body ground NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
7. CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 1 RELAY BLOCK, JUNCTION BLOCK - BATTERY AND BODY GROUND) Remove the PTC NO. 1 relay from the engine room No. 1 relay block, junction block. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 5 - Body ground Always 11 to 14 V Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC NO. 1 relay terminal 2 - Body ground Always Below 1 ohms TEXT IN ILLUSTRATION *1 PTC NO. 1 Relay *a Component without relay installed (Engine Room No. 1 Relay Block, Junction Block) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
8. CHECK HARNESS AND CONNECTOR (ENGINE ROOM NO. 2 RELAY BLOCK - BATTERY AND BODY GROUND) Remove the PTC NO. 2 and PTC NO. 3 relays from the engine room No. 2 relay block. Measure the voltage according to the value(s) in the table below. Standard Voltage Tester Connection Condition Specified Condition PTC NO. 2 relay terminal 5 - Body ground Always 11 to 14 V PTC NO. 3 relay terminal 5 - Body ground Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition PTC NO. 2 relay terminal 2 - Body ground Always Below 1 ohms PTC NO. 3 relay terminal 2 - Body ground TEXT IN ILLUSTRATION *1 PTC NO. 2 Relay *2 PTC NO. 3 Relay *a Component without relay installed (Engine Room No. 2 Relay Block) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
9. INSPECT QUICK HEATER ASSEMBLY Remove the quick heater assembly. Refer to «REMOVAL»(ref-422116-S22399775842011092600000) . Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition 1 (B) - 1 (E) Always Below 1 kohms 2 (B) - 1 (E) 2 (B) - 2 (E) 3 (B) - 2 (E) NG --> See step 11 OK: Go to next step
10. CHECK HARNESS AND CONNECTOR (QUICK HEATER - BODY GROUND) Disconnect the F86 heater connector. Measure the resistance according to the value(s) in the table below. Standard Resistance Tester Connection Condition Specified Condition F86-1 (E) - Body ground Always Below 1 ohms F86-2 (E) - Body ground TEXT IN ILLUSTRATION *a Front view of wire harness connector (to Quick Heater Assembly) NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK --> See step 12
11. REPLACE QUICK HEATER ASSEMBLY. Refer to «REMOVAL»(ref-422116-S22399775842011092600000)
12. PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to «PROBLEM SYMPTOMS TABLE»(ref-422144-S39567940892011092600000)

When the engine is started, the generator assembly turns on and a voltage pulse signal is generated.

This signal is used by the air conditioning amplifier assembly.

The signal expressing the amount of output from the generator assembly is one element of PTC heater control.

Scheme 217

The main power source is supplied to the air conditioning amplifier assembly when the ignition switch is turned to ON. The power source is used for operating the air conditioning amplifier assembly, servo motors, etc.

Scheme 218

The back-up power source circuit for the air conditioning amplifier assembly is shown below. Power is supplied even after the ignition switch is turned off and is used for diagnostic trouble code memory, etc.

Scheme 219