INSPECTION PROCEDURE
14: The PTC heater does not work. <Diesel engine>
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COMMENTS ON TROUBLE SYMPTOM
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If the PTC heater does not work when the following conditions are met, the PTC heater,
PTC heater relay, heater control panel or A/C control panel, or wiring harness, connector(s)
may be defective.
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- Blower knob: Other than OFF
- The engine is running.
- The engine coolant temperature is 77°C or lower.
- Temperature adjustment knob: MAX HOT
- During low-electric load conditions
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- Malfunction of the PTC heater
- Malfunction of the PTC heater relay1
- Malfunction of the PTC heater relay2
- Malfunction of the PTC heater relay3
- Damaged wiring harness or connectors
- Malfunction of the heater control panel or A/C control panel
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STEP 1. M.U.T.-III diagnosis code
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Check that the air conditioner has not set a diagnosis code.
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Q.
Is the diagnosis code set?
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 Carry out the diagnosis code procedures. Refer to  .
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 Go to Step 2.
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STEP 2. M.U.T.-III other system’s diagnosis code
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Check that the ETACS-ECU has not set a diagnosis code.
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Q.
Is the diagnosis code set?
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Carry out the diagnosis code procedures. Refer to GROUP 54A, ETACS-ECU .
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Go to Step 3.
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STEP 3. Connector check: A-29X PTC heater relay1 connector, A-36X
PTC heater relay2 connector and A-28X PTC heater relay3 connector
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the connector concerned.
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STEP 4. Check the PTC heater relay1, 2 and 3.
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Refer to .
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Q.
Is the check result normal?
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Go to Step 5.
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Replace the PTC heater relay1, 2 or 3.
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STEP 5. Connector check: C-06 PTC heater connector and C-237 heater
control panel or C-216 A/C control panel connector
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Q.
Is the check result normal?
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Repair the connector concerned.
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STEP 6. Measure the voltage at C-06 PTC heater connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Disconnect the connector C-237 heater control panel or C-216 A/C control panel and
earth terminal 4.
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(4)Voltage between terminal 2 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 13.
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Go to Step 7.
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STEP 7. Measure the voltage at A-29X PTC heater relay1 connector.
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(1)Remove the relay, and measure at the relay side.
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(2)Voltage between terminal 2 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 9.
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Go to Step 8.
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STEP 8. Check the wiring harness between A-29X PTC heater relay1 connector
terminal No. 2 and fusible link (40) connector.
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- Check the power supply line for open circuit.
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| note |
Prior to the wiring harness inspection, check glow control relay connector A-34X, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 9. Measure the voltage at A-29X PTC heater relay1 connector.
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(1)Remove the relay, and measure at the relay side.
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(2)Turn the ignition switch to the "ON" earth position.
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(3)Voltage between terminal 3 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 11.
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Go to Step 10.
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STEP 10. Check the wiring harness between A-29X PTC heater relay1
connector terminal No. 3 and C-417 ETACS-ECU connector terminal No. 5.
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- Check the power supply line for open circuit.
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Prior to the wiring harness inspection, check intermediate connector C-127, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 11. Check the wiring harness wires between C-06 PTC heater connector
terminal No. 2 and A-29X PTC heater relay1 connector terminal No. 4.
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- Check the power supply line for open circuit.
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Q.
Is the check result normal?
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Go to Step 12.
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Repair the wiring harness.
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STEP 12. Check the wiring harness between A-29X PTC heater relay1
connector terminal No. 1 and C-237 heater control panel or C-216 A/C control panel connector
terminal No. 4.
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- Check the power supply line for open circuit.
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Prior to the wiring harness inspection, check intermediate connector C-128, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 13. Measure the voltage at C-06 PTC heater connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Disconnect the connector C-237 heater control panel or C-216 A/C control panel and
earth terminal 3.
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(4)Voltage between terminal 1 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 20.
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Go to Step 14.
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STEP 14. Measure the voltage at A-36X PTC heater relay2 connector.
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(1)Remove the relay, and measure at the relay side.
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(2)Voltage between terminal 4 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 16.
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Go to Step 15.
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STEP 15. Check the wiring harness between A-36X PTC heater relay2
connector terminal No. 4 and fusible link (41) connector.
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- Check the power supply line for open circuit.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 16. Measure the voltage at A-36X PTC heater relay2 connector.
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(1)Remove the relay, and measure at the relay side.
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(2)Turn the ignition switch to the "ON" earth position.
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(3)Voltage between terminal 1 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 18.
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Go to Step 17.
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STEP 17. Check the wiring harness between A-36X PTC heater relay2
connector terminal No. 3 and C-417 ETACS-ECU connector terminal No. 5.
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- Check the power supply line for open circuit.
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Prior to the wiring harness inspection, check intermediate connector C-127, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 18. Check the wiring harness wires between C-06 PTC heater connector
terminal No. 1 and A-36X PTC heater relay2 connector terminal No. 2.
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- Check the power supply line for open circuit.
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Q.
Is the check result normal?
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Go to Step 19.
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Repair the wiring harness.
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STEP 19. Check the wiring harness between A-36X PTC heater relay2
connector terminal No. 1 and C-237 heater control panel or C-216 A/C control panel connector
terminal No. 3.
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- Check the power supply line for open circuit.
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Prior to the wiring harness inspection, check intermediate connector C-128, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 20. Measure the voltage at C-06 PTC heater connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Disconnect the connector C-237 heater control panel or C-216 A/C control panel and
earth terminal 5.
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(4)Voltage between terminal 3 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 27.
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Go to Step 21.
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STEP 21. Measure the voltage at A-28X PTC heater relay3 connector.
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(1)Remove the relay, and measure at the relay side.
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(2)Voltage between terminal 4 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 23.
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Go to Step 22.
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STEP 22. Check the wiring harness between A-28X PTC heater relay3
connector terminal No. 4 and fusible link (41) connector.
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- Check the power supply line for open circuit.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 23. Measure the voltage at A-28X PTC heater relay3 connector.
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(1)Remove the relay, and measure at the relay side.
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(2)Turn the ignition switch to the "ON" earth position.
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(3)Voltage between terminal 3 and body earth
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 25.
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Go to Step 24.
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STEP 24. Check the wiring harness between A-28X PTC heater relay3
connector terminal No. 1 and C-417 ETACS-ECU connector terminal No. 5.
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- Check the power supply line for open circuit.
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Prior to the wiring harness inspection, check intermediate connector C-127, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 25. Check the wiring harness wires between C-06 PTC heater connector
terminal No. 3 and A-28X PTC heater relay3 connector terminal No. 3.
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- Check the power supply line for open circuit.
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Q.
Is the check result normal?
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Go to Step 26.
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Repair the wiring harness.
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STEP 26. Check the wiring harness between A-28X PTC heater relay3
connector terminal No. 2 and C-237 heater control panel or C-216 A/C control panel connector
terminal No. 5.
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- Check the power supply line for open circuit.
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Prior to the wiring harness inspection, check intermediate connector C-128, and repair
if necessary.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 27. Connector check: C-07 PTC heater connector
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Q.
Is the check result normal?
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Go to Step 28.
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Repair the connector.
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STEP 28. Resistance measurement at C-07 PTC heater connector.
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Continuity between terminal 1, 2 and body earth.
OK: Continuity (2Ω or less)
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Q.
Is the check result normal?
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Go to Step 30.
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Go to Step 29.
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STEP 29. Check the wiring harness between C-07 PTC heater connector
(terminals 1 and 2) and body earth.
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- Check the PTC heater earth line for open circuit.
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection
Service Points - How to Cope with Intermittent Malfunction ).
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Repair the wiring harness.
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STEP 30. Check the PTC heater.
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Refer to .
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Q.
Is the check result normal?
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Replace the heater control panel or A/C control panel.
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Replace the PTC heater.
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