Inspection Procedure 12: The PTC heater does not work <LHD>

COMMENTS ON TROUBLE SYMPTOM
When the PTC heater does not work under the following conditions, the PTC heater switch system or the PTC heater circuit system may be defective.
PTC heater operating conditions
  • PTC heater switch: ON
  • Air outlet: FOOT/DEF, FOOT, FACE/FOOT
  • Temperature control dial: MAX HOT
  • Coolant temperature: 82 degrees celsius or less
note When the coolant temperature becomes above 82 degrees celsius and PTC heater stops the operation, the PTC heater does not operate until coolant temperature becomes below 72 degrees celsius.

PROBABLE CAUSES

  • Malfunction of the PTC heater switch system
  • Damaged the wiring harness or connectors
  • Malfunction of the PTC heater relay 1
  • Malfunction of the PTC heater relay 2
  • Malfunction of the PTC heater
  • Malfunction of the automatic air conditioner control panel (A/C-ECU)

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list
Check that the following service data display contents are normal. (Refer to .)

  • Item 35: PTC heater switch

Q. Does the blower motor work normally?

Go to Step 4.
Go to Step 2.

STEP 2. Connector check: C-106 A/C-ECU connector

Q. Is the check result normal?

Go to Step 3.

Repair the connector.

STEP 3. Voltage measurement at C-106 A/C-ECU connector.

(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the "ON" position.
(3)Turn the PTC heater switch to the "ON" position.

(4)Voltage between terminal 26 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 28.

Inspection Procedure 28: Refer to PTC heater switch system <LHD> .

STEP 4. Connector check: C-103 PTC heater connector

Q. Is the check result normal?

Go to Step 5.

Repair the connector.

STEP 5. Resistance measurement at the C-103 PTC heater connector.

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Continuity between terminal 1 and body earth
OK: 2Ω or less

Q. Is the check result normal?

Go to Step 7.

Go to Step 6.

STEP 6. Check the wiring harness between C-103 PTC heater connector terminal No.1 and body earth.


  • Check the PTC heater earth line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 7. Resistance measurement at the C-103 PTC heater connector.

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Continuity between terminal 3 and body earth
OK: 2Ω or less

Q. Is the check result normal?

Go to Step 9.

Go to Step 8.

STEP 8. Check the wiring harness between C-103 PTC heater connector terminal No.3 and body earth.


  • Check the PTC heater earth line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 9. Connector check: C-105 A/C-ECU connector

Q. Is the check result normal?

Go to Step 10.

Repair the connector.

STEP 10. Voltage measurement at C-103 PTC heater connector.

(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the "ON" position.


(3)Disconnect A/C-ECU connector C-105 and earth terminal 46.

(4)Voltage between terminal 2 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 19.

Go to Step 11.

STEP 11. Connector check: C-206 PTC heater relay 1 controller connector

Q. Is the check result normal?

Go to Step 12.

Repair the connector.

STEP 12. Check the PTC heater switch relay 1 continuity.
Refer to .

Q. Is the PTC heater switch relay 1 in good condition?
Go to Step 13.
Replace the PTC heater switch relay 1.

STEP 13. Voltage measurement at C-206 PTC heater relay 1 connector.

(1)Remove the relay, and measure at the relay block side.
(2)Turn the ignition switch to the "ON" position.

(3)Voltage between terminal 3 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 15.

Go to Step 14.

STEP 14. Check the wiring harness between C-206 PTC heater relay 1 connector terminal No.3 and the ignition switch (IG2).


note Prior to the wiring harness inspection, check junction block connectors C-202, C-203 and joint connector C-32, and repair if necessary.

  • Check the PTC heater relay 1 earth supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 15. Voltage measurement at C-206 PTC heater relay 1 connector.

(1)Remove the relay, and measure at the relay block side.

(2)Voltage between terminal 4 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 17.

Go to Step 16.

STEP 16. Check the wiring harness between C-206 PTC heater relay 1 connector terminal No.4 and the fusible link (28).


note Prior to the wiring harness inspection, check intermediate connector C-124, and repair if necessary.

  • Check the PTC heater relay 1 power supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 17. Check the wiring harness between C-206 PTC heater relay 1 connector terminal No.1 and C-105 A/C-ECU connector terminal No.46.


note Prior to the wiring harness inspection, check joint connector C-01, and repair if necessary.

  • Check the PTC heater relay 1 earth line for open or short circuit.

Q. Is the check result normal?

Go to Step 18.

Repair the wiring harness.

STEP 18. Check the wiring harness between C-206 PTC heater relay 1 connector terminal No.5 and C-103 PTC heater connector terminal No.2.



  • Check the PTC heater relay 1 power supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 19. Voltage measurement at C-103 PTC heater connector.

(1)Disconnect the connector, and measure at the wiring harness side.
(2)Turn the ignition switch to the "ON" position.


(3)Disconnect A/C-ECU connector C-105 and earth terminal 46.

(4)Voltage between terminal 4 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 28.

Go to Step 20.

STEP 20. Connector check: C-207 PTC heater relay 2 controller connector

Q. Is the check result normal?

Go to Step 21.

Repair the connector.

STEP 21. Check the PTC heater relay 2 continuity.
Refer to .

Q. Is the PTC heater relay 2 in good condition?
Go to Step 22.
Replace the PTC heater relay 2.

STEP 22. Voltage measurement at C-207 PTC heater relay 2 connector.

(1)Remove the relay, and measure at the relay block side.
(2)Turn the ignition switch to the "ON" position.

(3)Voltage between terminal 3 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 24.

Go to Step 23.

STEP 23. Check the wiring harness between C-207 PTC heater relay 2 connector terminal No.3 and the ignition switch (IG2).


note Prior to the wiring harness inspection, check junction block connectors C-202, C-203 and joint connector C-32, and repair if necessary.

  • Check the PTC heater relay 2 power supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 24. Voltage measurement at C-207 PTC heater relay 2 connector.

(1)Remove the relay, and measure at the relay block side.

(2)Voltage between terminal 4 and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 26.

Go to Step 25.

STEP 25. Check the wiring harness between C-207 PTC heater relay 2 connector terminal No.4 and the fusible link (28).


note Prior to the wiring harness inspection, check intermediate connector C-124, and repair if necessary.

  • Check the PTC heater relay 2 power supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 26. Check the wiring harness between C-207 PTC heater relay 2 connector terminal No.1 and C-105 A/C-ECU connector terminal No.46.


note Prior to the wiring harness inspection, check joint connector C-01, and repair if necessary.

  • Check the PTC heater relay 2 earth line for open or short circuit.

Q. Is the check result normal?

Go to Step 27.

Repair the wiring harness.

STEP 27. Check the wiring harness between C-207 PTC heater relay 2 connector terminal No.5 and C-103 PTC heater connector terminal No.4.



  • Check the PTC heater power supply line for open circuit.

Q. Is the check result normal?

The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).

Repair the wiring harness.

STEP 28. Check the trouble symptom
Check that the PTC heater works normally.

Q. Is the check result normal?
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
Replace the A/C-ECU.