Inspection Procedure 24: 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 switch module<manual A/C> or A/C-ECU<automatic A/C>, the engine-ECU turns ON the PTC heater relay 1 and 2 after satisfying all the operation conditions.
  
Operation conditions of PTC heater relay 1

1. Engine coolant temperature is under 80°C
   
2. 2 seconds later after the engine has start up.
   
3. The PTC heater request signal has been input continuously 2 seconds or more
   
4. The battery voltage continues to be 12.3 V or more for 12 seconds or more.
   
Operation conditions of PTC heater relay 2

1. Engine coolant temperature is under 75°C.
   
2. The PTC heater 1 has been ON continuously 45 seconds or more.
   
3. Heater switch (warm up switch) is ON or vehicle speed is 20km/h or more.
   
4. The battery voltage continues to be 12.9 V or more for 12 seconds or more.
   

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 25.
  
• Damaged connector (PTC heater relay connector, PTC heater connector, engine-ECU connector).
  
• Failed engine-ECU
  

	Go to Step 2 .

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

Disconnect the C-105 connector. Using the jumper wire, connect terminal No. 38 to earth. OK: The PTC heater 1 operates. Q. Is the check result normal? Go to Step 3 . Check PTC heater system (Refer to GROUP 55A - Troubleshooting - Trouble Symptom Chart ).

Disconnect the C-105 connector. Using the jumper wire, connect terminal No.41 to earth. OK: The PTC heater 2 operates. Q. Is the check result normal? Go to Step 4 . Check PTC heater system (Refer to GROUP 55A - Troubleshooting - Trouble Symptom Chart ).

Q. Is the check result normal? Go to Step 5 . Repair or replace.

	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 ).