SFI SYSTEM > ECM Power Source Circuit

for Preparation Click here


DESCRIPTION

When the ignition switch is turned ON, the 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 EFI relay and supplying power to terminal +B of the ECM.

WIRING DIAGRAM


G037762E02


INSPECTION PROCEDURE

1.CHECK ECM (+B VOLTAGE)
A066060E20

  1. Turn the ignition switch ON.

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    E9-1 (+B) - E12-3 (E1)
    		9 to 14 V



OK
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
NG


2.CHECK WIRE HARNESS (ECM - BODY GROUND)
A065159E03

  1. Disconnect the E12 ECM connector.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    E12-3 (E1) - Body ground
    		Below 1 Ω



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK ECM (IGSW VOLTAGE)
A066060E21

  1. Turn the ignition switch ON.

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    E9-9 (IGSW) - E12-3 (E1)
    		9 to 14 V



OK
Go to step 6
NG


4.INSPECT FUSE (IGN)
G034718E01

  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 HARNESSES AND COMPONENTS CONNECTED TO FUSE
OK


5.INSPECT IGNITION OR STARTER SWITCH ASSEMBLY
A087913E02

  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)
    		LOCK
    		10 kΩ or higher
    5 - 6
    		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.CHECK ECM (MREL VOLTAGE)
A066060E55

  1. Turn the ignition switch ON.

  1. Measure the voltage of the ECM connectors.

    Standard voltage:
    Tester Connection
    		Specified Condition
    E9-8 (MREL) - E12-3 (E1)
    		9 to 14 V



NG
REPLACE ECM
OK


Go to step 6

7.INSPECT FUSE (EFI)
G034719E05

  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.CHECK INTEGRATION RELAY (MAIN RELAY)
G034717E03

  1. Disconnect the 1J integration relay connector from the engine room junction block (Click here).

  1. Measure the voltage of the MAIN 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 (MAIN RELAY - ECM, MAIN RELAY - BODY GROUND)
G034949E01

  1. Disconnect the 1J integration relay connector from the engine room junction block (Click here).

  1. Disconnect the E9 ECM connector.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    1J-2 - E9-8 (MREL)
    		Below 1 Ω
    1J-4 - E9-1 (+B)
    		Below 1 Ω
    1J-3 - Body ground
    		Below 1 Ω
    1J-2 or E9-8 (MREL) - Body ground
    		10 kΩ or higher
    1J-4 or E9-1 (+B) - Body ground
    		10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

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