ECM Power Source Circuit

3UR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: ECM Power Source Circuit
- ECM Power Source Circuit

DESCRIPTION

When the ignition switch is turned to ON, the battery voltage is applied to the IGSW of the ECM. The output signal from the MREL terminal of the ECM causes a current to flow to the coil, closing the contacts of the integration relay (EFI relay) and supplying power to either terminal +B or +B2 of the ECM.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT FUSES (AM2, IG2 MAIN, EFI NO. 1, IGN)





(a) Remove the AM2 fuse, IG2 MAIN fuse, EFI NO. 1 fuse and IGN fuse from the engine room relay block.

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

Standard resistance:





NG -- CHECK FOR SHORT IN ALL HARNESSES AND CONNECTORS CONNECTED TO FUSE AND REPLACE FUSE
OK -- Continue to next step.

2. INSPECT RELAY (IG2, EFI)





(a) Remove the integration relay from the engine room relay block.

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

Standard resistance:





NG -- REPLACE RELAY Component Tests and General Diagnostics
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (ECM - BODY GROUND)





(a) Disconnect the D74 ECM connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

4. INSPECT ECM (IGSW VOLTAGE)





(a) Disconnect the A24 and D74 ECM connectors.

(b) Turn the ignition switch to ON.

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

Standard voltage:





NG -- CHECK HARNESS AND CONNECTOR (RELAY BLOCK - ECM, IGNITION SWITCH, BATTERY AND BODY GROUND)

OK -- REPLACE ECM Removal

5. CHECK HARNESS AND CONNECTOR (RELAY BLOCK - ECM, IGNITION SWITCH, BATTERY AND BODY GROUND)





(a) Disconnect the A24 ECM connector.

(b) Disconnect the J9 ignition switch connector.

(c) Disconnect the cable from the battery positive (+) terminal.

(d) Remove the AM2 fuse and integration relay.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. INSPECT IGNITION SWITCH

(a) Inspect the ignition switch Testing and Inspection.

NG -- REPLACE IGNITION SWITCH Removal
OK -- Continue to next step.

7. CHECK HARNESS AND CONNECTOR (INTEGRATION RELAY - ECM, BATTERY AND BODY GROUND)





(a) Disconnect the A24 ECM connector.

(b) Disconnect the cable from the battery positive terminal.

(c) Remove the integration relay from the engine room relay block.

(d) Disconnect the integration relay connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPAIR OR REPLACE ENGINE ROOM RELAY BLOCK