ECM Power Source Circuit: Wiring Diagram

Fig 1: ECM Power Source Circuit - Wiring Diagram

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CHECK ECM (+B VOLTAGE)

Turn the ignition switch ON.

Measure the voltage of the ECM connectors.

Standard voltage

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
+B (E4-1) - E1 (E6-1)	9 to 14 V

OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN ON PROBLEM SYMPTOMS TABLE

Fig 2: Identifying Terminals Of E6 ECM Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: GO TO NEXT STEP.

CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)

Disconnect the E6 ECM connector.

Measure the resistance of the wire harness side connector.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
E1 (E6-1) - Body ground	Below 1 Ω

NG: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 3: Disconnecting E6 ECM Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: GO TO NEXT STEP.

CHECK ECM (IGSW VOLTAGE)

Turn the ignition switch ON.

Measure the voltage of the ECM connectors.

Standard voltage

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
IGSW (E4-9) - E1 (E6-1)	9 to 14 V

NG: Go to step 6

Fig 4: Identifying Terminals Of ECM Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG: GO TO NEXT STEP.

INSPECT FUSE (IGN1)
1. Remove the IGN1 fuse from the instrument panel junction block RH.
2. Measure the resistance of the IGN1 fuse.
  Standard resistance: Below 1 Ω
NG: CHECK FOR SHORT IN ALL HARNESS AND COMPONENTS CONNECTED TO IGN1 FUSE, AND REPLACE IGN1 FUSE

Fig 5: Removing IGN1 Fuse From Instrument Panel Junction Block RH
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: GO TO NEXT STEP.

INSPECT IGNITION SWITCH ASSEMBLY

Remove the lower finish panel.
Disconnect the I18 ignition switch connector.

Measure the resistance of the ignition switch.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

Switch position	Tester Connection	Specified Condition
LOCK	Always	10 kΩ or higher
ACC	1-3	Below 1 Ω
ON	1-2-3 5-6
START	1-2 4-5-6

Fig 6: Identifying Terminals Of I18 Ignition Switch Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Reconnect the ignition switch connector.

NG: REPLACE IGNITION SWITCH ASSEMBLY

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

CHECK ECM (MREL VOLTAGE)

Turn the ignition switch ON.

Measure the voltage of the ECM connectors.

Standard voltage

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
MREL (E4-8) - E1 (E6-1)	9 to 14 V

NG: REPLACE ECM

Fig 7: Identifying Terminals Of ECM Connector

OK: GO TO NEXT STEP.

INSPECT FUSE (EFI NO. 1)
1. Remove the EFI NO. 1 fuse from the engine room junction block.
2. Measure the resistance of the EFI NO. 1 fuse.
  Standard resistance: Below 1 Ω
NG: CHECK FOR SHORT IN ALL HARNESS AND COMPONENTS CONNECTED TO EFI NO. 1 FUSE, AND REPLACE EFI FUSE

Fig 8: Removing EFI No. 1 Fuse From Engine Room Junction Block
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK: GO TO NEXT STEP.

INSPECT EFI RELAY (Marking: EFI OR ECD)

Remove the EFI relay from the engine room junction block.

Measure the resistance of the EFI relay.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

Terminal Connection	Specified Condition
3 - 5	10 kΩ or higher
3 - 5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

NG: REPLACE EFI RELAY

Fig 9: Measuring Resistance Of EFI Relay

OK: GO TO NEXT STEP.

CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)

Disconnect the E4 ECM connector.

Measure the resistance between the wire harness side connector and body ground.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
MREL (E4-8) - Body ground	Below 1 Ω

Reconnect the ECM connector.

OK: REPAIR OR REPLACE HARNESS OR CONNECTOR

Fig 10: Disconnecting E4 ECM Connector

NG: CHECK FOR INTERMITTENT PROBLEMS