Inspection Procedure 26: 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. 6) 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 ignition switch, PTC heater relay and PTC heater, PTC heater and body earth, and open circuit between PTC heater relay and battery.
  • 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 .

  1. 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 Symptoms ).

STEP 2. PTC heater 1 operation check

  • Disconnect the D-213 connector.
  • Using the jumper wire, connect terminal No. 46 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 - Precautions Before Service - 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 ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).