SFI SYSTEM MIL Circuit

DESCRIPTION

The MIL (Malfunction Indicator Lamp) is used to indicate vehicle malfunctions detected by the ECM. When the ignition switch is turned to ON, power is supplied to the MIL circuit, and the ECM provides the circuit ground which illuminates the MIL.

The MIL operation can be checked visually: When the ignition switch is turned to ON, the MIL should be illuminated and should turn off after engine is started. If the MIL remains illuminated or is not illuminated, conduct the following troubleshooting procedure using the GTS.

WIRING DIAGRAM

PROCEDURE

1. CHECK THAT MIL IS ILLUMINATED

   
   

   1. Perform troubleshooting in accordance with the table below.

      Result
      Condition Result Proceed to MIL remains ON Ignition switch ON → engine is started A MIL does not illuminate Ignition switch ON → engine is started (sometimes does not start) B MIL ON → MIL OFF Ignition switch ON → engine is started C

   
   

   B

   CHECK THAT ENGINE STARTS Click here

   C

   CHECK FOR INTERMITTENT PROBLEMS Click here

   A

2. CHECK WHETHER DTC OUTPUT RECURS

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Enter the following menus: System Select / Health Check.

   5. Read the DTCs using the GTS.

      Result
      Result Proceed to DTCs is output A DTCs are not output B

      Tech Tips

      Check for detected DTCs output from other ECUs which relate to the MIL.

   
   

   A

   GO TO DTC CHART

   B

3. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT IN WIRE HARNESS)

   
   
   1. 

      *a	Front view of wire harness connector (to ECM)

      Disconnect the A173 ECM connector.

   2. Turn the ignition switch to ON.

   3. Check that the MIL is not illuminated.

      OK
      MIL is not illuminated.

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE ECM Click here

   NG

4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM)

   
   

   1. Disconnect the combination meter assembly connector.

   2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition E46-11 (CHK) or A173-27 (W) - Body ground Always 10 kΩ or higher

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE COMBINATION METER ASSEMBLY Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

5. CHECK THAT ENGINE STARTS

   
   

   1. Turn the ignition switch to ON.

   2. Start the engine.

      Result
      Result Proceed to Engine starts A Engine does not start* B

      Tech Tips

      *: The GTS cannot communicate with the ECM.

   
   

   B

   GO TO VC OUTPUT CIRCUIT Click here

   A

6. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY VOLTAGE)

   
   

   1. Disconnect the combination meter 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 Condition Specified Condition E46-39 (IG+) - Body ground Ignition switch ON 11 to 14 V

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

   OK

7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - ECM)

   
   

   1. Disconnect the combination meter assembly connector.

   2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition E46-11 (CHK) - A173-27 (W) Always Below 1 Ω

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE COMBINATION METER ASSEMBLY Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR