Inspection Procedure 28: PTC heater relay system <Vehicle with PTC heater>

OPERATION

When the PTC heater operation request signal (battery voltage) is input into the engine-ECU (terminal No. 35) from the A/C-ECU, the engine-ECU turns ON the PTC heater relay 1 and 2 after satisfying all the operation conditions.

PROBABLE CAUSES

Failed PTC heater relay
Failed PTC heater
Damaged harness (Open circuit between PTC heater relay and engine-ECU, PTC heater relay and J/B, PTC heater relay and PTC heater, PTC heater and body earth, and open circuit between PTC heater relay and fusible link 30.
Damaged connector (PTC heater relay connector, PTC heater connector, engine-ECU connector).
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Refer to Data List Reference Table .

Item 76 PTC heater 1 relay

Q. Is the check result normal?

	Go to Step 2.

	Check PTC heater system (Refer to GROUP 55 - Troubleshooting - Check Chart for Trouble Symptom Chart ).

STEP 2. PTC heater 1 operation check

Disconnect the D-213 connector.
Using the jumper wire, connect terminal No. 41 to earth.

OK: The PTC heater operates.

Q. Is the check result normal?

	Go to Step 3.

	Check PTC heater system (Refer to GROUP 55 - Troubleshooting - Check Chart for Trouble Symptom Chart ).

STEP 3. Connector check: D-213 engine-ECU connector.

Q. Is the check result normal?

	Go to Step 4.

	Repair or replace.

STEP 4. Check the trouble symptoms.

Q. Does trouble symptom persist?

	Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ).

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