INSPECTION PROCEDURE 13: The PTC heater does not work <4N1>.

COMMENTS ON TROUBLE SYMPTOM

With the engine and blower motor being operated, if the PTC heater does not operate by setting the heater control to MAX HOT at the coolant temperature of 75 °C or lower, the PTC heater, PTC heater relay, heater controller assembly (A/C-ECU) or its circuit system may be faulty.

PROBABLE CAUSES

Malfunction of the PTC heater
Malfunction of the PTC heater relay 1
Malfunction of the PTC heater relay 2
Malfunction of the PTC heater relay 3
Damaged the wiring harness or connectors
Malfunction of the heater controller assembly (A/C-ECU)

DIAGNOSTIC PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Check that the air conditioner has not set a diagnosis code.

Q. Is the diagnosis code set?

	Carry out the diagnosis code procedures. Refer to .

	Go to Step 2.

STEP 2. M.U.T.-III other system’s diagnosis code

Check that the ETACS-ECU has not set a diagnosis code.

Q. Is the diagnosis code set?

	Carry out the diagnosis code procedures. Refer to GROUP 54A, ETACS-ECU .

	Go to Step 3.

STEP 3. Check the PTC heater relay 1, 2 and 3.

Refer to

Q. Is the check result normal?

	Go to Step 4.

	Replace the PTC heater relay 1, 2 or 3.

STEP 4. Measure the voltage at C-29 PTC heater connector.

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

(2)Ignition switch: ON

(3)Disconnect heater controller assembly (A/C-ECU) connector C-111 and earth terminal 6.

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

Q. Is the check result normal?

	Go to Step 11.

	Go to Step 5.

STEP 5. Measure the voltage at A-25X PTC heater relay 1 connector.

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

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

Q. Is the check result normal?

	Go to Step 7.

	Go to Step 6.

STEP 6. Check the wiring harness between PTC heater relay 1 connector terminal No. 2 and fusible link (8) for open circuit.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 7. Measure the voltage at PTC heater relay 1 connector.

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

(2)Turn the ignition switch to the "ON" earth position.

(3)Voltage between terminal 1 and body earth
OK: System voltage

Q. Is the check result normal?

	Go to Step 9.

	Go to Step 8.

STEP 8. Check the wiring harness between PTC heater relay 1 connector terminal No. 1 and the ETACS-ECU for open circuit.

note

Prior to the wiring harness inspection, check intermediate connector and repair if necessary.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 9. Check the wiring harness between PTC heater connector terminal No. 2 and PTC heater relay 1 connector terminal No. 4 for open circuit.

Q. Is the check result normal?

	Go to Step 10.

	Repair the connector(s) or wiring harness.

STEP 10. Check the wiring harness between PTC heater relay 1 connector terminal No. 3 and heater controller assembly (A/C-ECU) HTR1 for open circuit.

note

Prior to the wiring harness inspection, check intermediate connector, and repair if necessary.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 11. Measure the voltage at PTC heater connector.

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

(2)Ignition switch: ON

(3)Disconnect heater controller assembly (A/C-ECU) connector and earth terminal 7.

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

Q. Is the check result normal?

	Go to Step 18.

	Go to Step 12.

STEP 12. Measure the voltage at PTC heater relay 2 connector.

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

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

Q. Is the check result normal?

	Go to Step 14.

	Go to Step 13.

STEP 13. Check the wiring harness between PTC heater relay 2 connector terminal No. 2 and fusible link (9) for open circuit.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 14. Measure the voltage at PTC heater relay 2 connector.

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

(2)Turn the ignition switch to the "ON" earth position.

(3)Voltage between terminal 1 and body earth
OK: System voltage

Q. Is the check result normal?

	Go to Step 16.

	Go to Step 15.

STEP 15. Check the wiring harness between PTC heater relay 2 connector terminal No. 1 and the ETACS-ECU for open circuit.

note

Prior to the wiring harness inspection, check intermediate connector, and repair if necessary.

Check the power supply line for open circuit.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 16. Check the wiring harness between PTC heater connector terminal No. 3 and PTC heater relay 2 connector terminal No. 2 for open circuit.

Q. Is the check result normal?

	Go to Step 17.

	Repair the connector(s) or wiring harness.

STEP 17. Check the wiring harness between PTC heater relay 1 connector terminal No. 3 and heater controller assembly (A/C-ECU) HTR1 for open circuit.

note

Prior to the wiring harness inspection, check intermediate connector, and repair if necessary.

Check the power supply line for open circuit.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 18. Measure the voltage at PTC heater connector.

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

(2)Ignition switch: ON

(3)Disconnect heater controller assembly (A/C-ECU) connector and earth terminal 5.

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

Q. Is the check result normal?

	Go to Step 25.

	Go to Step 19.

STEP 19. Measure the voltage at PTC heater relay 3 connector.

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

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

Q. Is the check result normal?

	Go to Step 21.

	Go to Step 20.

STEP 20. Check the wiring harness between PTC heater relay 3 connector terminal No. 3 and fusible link (9) for open circuit.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 21. Measure the voltage at A-24X PTC heater relay 3 connector.

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

(2)Turn the ignition switch to the "ON" earth position.

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

Q. Is the check result normal?

	Go to Step 23.

	Go to Step 22.

STEP 22. Check the wiring harness between PTC heater relay 3 connector terminal No. 2 and the ETACS-ECU for open circuit.

note

Prior to the wiring harness inspection, check intermediate connector, and repair if necessary.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 23. Check the wiring harness between PTC heater connector terminal No. 1 and PTC heater relay 3 connector terminal No. 4 for open circuit.

Q. Is the check result normal?

	Go to Step 24.

	Repair the connector(s) or wiring harness.

STEP 24. Check the wiring harness between PTC heater relay 3 connector terminal No. 1 and heater controller assembly (A/C-ECU) HTR3 for open circuit.

note

Prior to the wiring harness inspection, check intermediate connector, and repair if necessary.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the connector(s) or wiring harness.

STEP 25. Resistance measurement at PTC heater connector.

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

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

Q. Is the check result normal?

	Go to Step 27.

	Go to Step 26.

STEP 26. PTC heater connector and body earth.

Check the PTC heater earth line for open circuit.

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).

	Repair the wiring harness.

STEP 27. Check the PTC heater.

Refer to

Q. Is the check result normal?

	Replace the heater controller assembly (A/C-ECU).

	Replace the PTC heater.