PRE-HEATING SYSTEM Pre-heating Control Circuit

DESCRIPTION

The glow plug is mounted inside the engine combustion chamber. To ensure efficient engine starting with a cold engine, the preheating timer assembly turns on the glow relay and permits the current to flow through the glow plug based on the preheating timer assembly calculated time. The glow plug is then heated, enabling fuel combustion with a cold engine.

WIRING DIAGRAM

Refer to System Diagram Click here.

INSPECTION PROCEDURE

PROCEDURE

1. CHECK GLOW RELAY (VOLTAGE)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Glow Relay)

      Remove the glow relay.

   2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition 1 - Body ground Always 11 to 14 V

   3. Reinstall the glow relay.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW RELAY - BATTERY)

   OK

2. CHECK GLOW RELAY (VOLTAGE)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Glow Relay)

      Remove the glow relay.

   2. Turn the ignition switch to ON.

   3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition 3 - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      Power voltage (12V) is applied for approximately 18 seconds after turning the ignition switch on.

   4. Reinstall the glow relay.

   
   

   NG

   CHECK PREHEATING TIMER ASSEMBLY Click here

   OK

3. CHECK GLOW RELAY (VOLTAGE)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Glow Relay)

      Remove the glow relay.

   2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition 3 - Body ground Engine cranking 11 to 14 V

   3. Reinstall the glow relay.

   
   

   NG

   CHECK HARNESS AND CONNECTOR (IGNITION SWITCH ASSEMBLY - GLOW RELAY) Click here

   OK

4. INSPECT GLOW RELAY

   
   
   1. 

      Text in Illustration

      *a	Component without harness connected (Glow Relay)

      Remove the glow relay.

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Specified Condition 1 - 2 10 kΩ or higher 3 - 4 Below 1 Ω

   3. Reinstall the glow relay.

   
   

   NG

   REPLACE GLOW RELAY

   OK

5. CHECK HARNESS AND CONNECTOR (GLOW RELAY - BODY GROUND)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Glow Relay)

      Remove the glow relay.

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition 4 - Body ground Always Below 1 Ω

   3. Reinstall the glow relay.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW RELAY - BODY GROUND)

   OK

6. CHECK HARNESS AND CONNECTOR (GLOW RELAY - GLOW PLUG ASSEMBLY)

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Glow Relay)
      *b	Front view of wire harness connector (to Glow Plug)

      Remove the glow relay.

   2. Disconnect the G1 glow plug assembly connector.

   3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition 2 - G1-1 Always Below 1 Ω

      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition 2 or G1-1 - Body ground Always 10 kΩ or higher

   4. Reconnect the G1 glow plug assembly connector.

   5. Reinstall the glow relay.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (GLOW RELAY - GLOW PLUG ASSEMBLY)

   OK

7. INSPECT GLOW PLUG ASSEMBLY (RESISTANCE)

   
   
   1. 

      Text in Illustration

      *1

      Ohmmeter

      Remove the glow plug assembly connector.

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition Glow plug terminal - Body ground 20°C (68°F) 0.72 Ω

      Tech Tips

      If any of the glow plugs has an open circuit, the engine power is insufficient only when the engine is cold.

      Note

      
      

      • Exercise extreme care not to damage the glow plug pipes. Damaging them could cause an open circuit, or shorten the life of the glow plugs.

      • Keep the glow plugs free of oil and fuel while cleaning.

      • Wipe any oil off of the terminal and Bakelite washer with a clean, dry cloth during inspection.

      • Do not apply more than 11 V to the glow plugs as doing so may cause an open circuit.

   3. Reinstall the glow plug assembly connector.

   
   

   NG

   REPLACE GLOW PLUG ASSEMBLY

   OK

8. CHECK GLOW PLUG ASSEMBLY (INSTALLATION)

   
   

   1. Check the glow plug assembly installation.

      OK
      Glow plug assemblies are installed securely.

      Torque:

      13 N*m  { 130 kgf*cm, 9 ft.*lbf }

   
   

   NG

   SECURELY REINSTALL GLOW PLUG ASSEMBLY

   OK

   SYSTEM IS OK

9. CHECK PREHEATING TIMER ASSEMBLY

   
   
   1. 

      Text in Illustration

      *a	Front view of wire harness connector (to Preheating Timer Assembly)

      Disconnect the P19 preheating timer assembly connector.

   2. Turn the ignition switch to ON.

   3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition P19-3 (IG) - P19-7 (EG) Ignition switch ON 11 to 14 V

   4. Reconnect the P19 preheating timer assembly connector.

   
   

   NG

   CHECK HARNESS AND CONNECTOR (PREHEATING TIMER ASSEMBLY - IGNITION SWITCH ASSEMBLY) Click here

   OK

10. CHECK HARNESS AND CONNECTOR (PREHEATING TIMER ASSEMBLY - GLOW RELAY)

    
    
    1. 

       Text in Illustration

       *a	Front view of wire harness connector (to Preheating Timer Assembly)
       *b	Front view of wire harness connector (to Glow Relay)

       Disconnect the P19 preheating timer assembly connector.

    2. Remove the glow relay.

    3. Measure the resistance according to the value(s) in the table below.

       Standard Resistance (Check for Open)
       Tester Connection Condition Specified Condition P19-1 (SREL) - 3 Always Below 1 Ω

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition P19-1 (SREL) or 3 - Body ground Always 10 kΩ or higher

    4. Reconnect the P19 preheating timer assembly connector.

    5. Reinstall the glow relay.

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (PREHEATING TIMER ASSEMBLY - GLOW RELAY)

    OK

    REPLACE PREHEATING TIMER ASSEMBLY

11. CHECK HARNESS AND CONNECTOR (IGNITION SWITCH ASSEMBLY - GLOW RELAY)

    
    
    1. 

       Text in Illustration

       *a	Front view of wire harness connector (to Ignition Switch Assembly)
       *b	Front view of wire harness connector (to Glow Relay)

       Disconnect the I15 ignition switch assembly connector.

    2. Remove the glow relay.

    3. Measure the resistance according to the value(s) in the table below.

       Standard Resistance (Check for Open)
       Tester Connection Condition Specified Condition I15-3 (ST1) - 3 Always Below 1 Ω

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition I15-3 (ST1) or 3 - Body ground Always 10 kΩ or higher

    4. Reconnect the I15 ignition switch assembly connector.

    5. Reinstall the glow relay.

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH ASSEMBLY - GLOW RELAY)

    OK

12. INSPECT IGNITION SWITCH ASSEMBLY

    
    

    1. Check the resistance.

       
       

       1. Using an ohmmeter, measure the resistance between the terminals.

          

          Standard resistance
          Condition Tester Connection Specified Condition LOCK Between all terminals 10 kΩ or higher ACC 4 (ACC) - 9 (AM1) Below 1 Ω ON 4 (ACC) - 9 (AM1) - 10 (IG1) 5 (AM2) - 8 (IG2) Below 1 Ω START 3 (ST1) - 9 (AM1) - 10 (IG1) 5 (AM2) - 8 (IG2) Below 1 Ω

    
    

    NG

    REPLACE IGNITION SWITCH ASSEMBLY

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH ASSEMBLY - BATTERY)

13. CHECK HARNESS AND CONNECTOR (PREHEATING TIMER ASSEMBLY - IGNITION SWITCH ASSEMBLY)

    
    

    1. Disconnect the P19 preheating timer assembly connector.

    2. Disconnect the I15 ignition switch assembly connector.

    3. Measure the resistance according to the value(s) in the table below.

       Standard Resistance (Check for Open)
       Tester Connection Condition Specified Condition P19-3 (IG) - I15-8 (IG2) Always Below 1 Ω

       Standard Resistance (Check for Short)
       Tester Connection Condition Specified Condition P19-3 (IG) or I15-8 (IG2) - Body ground Always 10 kΩ or higher

    4. Reconnect the I15 ignition switch assembly connector.

    5. Reconnect the P19 preheating timer assembly connector.

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (PREHEATING TIMER ASSEMBLY - IGNITION SWITCH ASSEMBLY)

    OK

14. INSPECT IGNITION SWITCH ASSEMBLY

    
    

    1. Check the resistance.

       
       

       1. Using an ohmmeter, measure the resistance between the terminals.

          

          Standard resistance
          Condition Tester Connection Specified Condition LOCK Between all terminals 10 kΩ or higher ACC 4 (ACC) - 9 (AM1) Below 1 Ω ON 4 (ACC) - 9 (AM1) - 10 (IG1) 5 (AM2) - 8 (IG2) Below 1 Ω START 3 (ST1) - 9 (AM1) - 10 (IG1) 5 (AM2) - 8 (IG2) Below 1 Ω

    
    

    NG

    REPLACE IGNITION SWITCH ASSEMBLY

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH ASSEMBLY - BATTERY)