GSIC - Global Service Information Center

### SFI SYSTEM > ECM Power Source Circuit

## for Preparation Click here

## DESCRIPTION

When the ignition switch is turned ON, battery voltage is applied to terminal IGSW of the ECM. The ECM "MREL" output signal causes a current to flow to the MAIN relay coil, closing the contacts of the MAIN relay and supplying power to terminal +B of the ECM.

## WIRING DIAGRAM

## INSPECTION PROCEDURE

1.INSPECT ECM (+B VOLTAGE)

1. Turn the ignition switch ON.

1. Measure the voltage of the ECM connectors.

   Standard voltage:
   Tester Connection | Specified Condition
   E14-1 (+B) - E17-1 (E1) | 9 to 14 V

| OK |

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

NG |

2.CHECK WIRE HARNESS (ECM - BODY GROUND)

1. Disconnect the E17 ECM connector.

1. Measure the resistance of the wire harness side connector.

   Standard resistance:
   Tester Connection | Specified Condition
   E17-1 (E1) - Body ground | Below 1 Ω

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

3.INSPECT ECM (IGSW VOLTAGE)

1. Turn the ignition switch ON.

1. Measure the voltage of the ECM connectors.

   Standard voltage
   Tester Connection | Specified Condition
   E14-9 (IGSW) - E17-1 (E1) | 9 to 14 V

| OK |

Go to step 6

NG |

4.INSPECT FUSE (IGN)

1. Remove the IGN fuse from the instrument panel junction block.

1. Measure the resistance of the fuse.

   Standard resistance:
     Below 1 Ω

| NG |

CHECK FOR SHORT IN ALL HARNESES AND COMPONENTS CONNECTED TO FUSE

OK |

5.INSPECT IGNITION OR STARTER SWITCH ASSEMBLY

1. Disconnect the I6 ignition switch connector.

1. Measure the resistance of the switch.

   Standard resistance:
   Tester Connection | Switch Condition | Specified Condition
   5 (AM2) - 6 (IG2) | OFF | 10 kΩ or higher
   5 (AM2) - 6 (IG2) | ON | Below 1 Ω

| NG |

REPLACE IGNITION OR STARTER SWITCH ASSEMBLY

OK |

REPAIR OR REPLACE HARNESS AND CONNECTOR (BATTERY - IGNITION SWITCH, IGNITION SWITCH - ECM)

6.INSPECT ECM (MREL VOLTAGE)

1. Turn the ignition switch ON.

1. Measure the voltage of the ECM connectors.

   Standard voltage:
   Tester Connection | Specified Condition
   E14-8 (MREL) - E17-1 (E1) | 9 to 14 V

| NG |

REPLACE ECM

OK |

7.INSPECT FUSE (EFI)

1. Remove the EFI fuse from the engine room junction block.

1. Measure the resistance of the fuse.

   Standard resistance:
     Below 1 Ω

| NG |

CHECK FOR SHORT IN ALL HARNESSES AND COMPONENTS CONNECTED TO FUSE

OK |

8.INSPECT INTEGRATION RELAY (MAIN RELAY)

1. Disconnect the integration relay from the engine room junction block.

1. Measure the voltage of the integration relay.

   Standard voltage:
   Tester Connection | Condition | Specified Condition
   1J-4 - Body ground | Ignition switch ON | 10 to 14 V

| NG |

REPLACE INTEGRATION RELAY

OK |

9.CHECK WIRE HARNESS (INTEGRATION RELAY- ECM, INTEGRATION RELAY - BODY GROUND)

1. Disconnect the 1J integration relay connector from the engine room junction block.

1. Disconnect the E14 ECM connector.

1. Measure the resistance of the wire harness side connectors.

   Standard resistance:

     Tester Connection | Specified Condition
     1J-2 - E14-8 (MREL) | Below 1 Ω
     1J-4 - E14-1 (+B) | Below 1 Ω
     1J-3 - Body ground | Below 1 Ω
     1J-2 or E14-8 (MREL) - Body ground | 10 kΩ or higher
     1J-4 or E14-1 (+B) - Body ground | 10 kΩ or higher

| NG |

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK |

REPAIR OR REPLACE HARNESS AND CONNECTOR (ECM - BATTERY POSITIVE TERMINAL)