Component Tests and General Diagnostics

2AZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: ECM Power Source Circuit

ECM Power Source Circuit

DESCRIPTION

When the ignition switch is turned to the ON position, the battery voltage is applied to 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 EFI relay and supplying power to either terminal +B or +B2 of the ECM.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

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





(a) Disconnect the ECM connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(c) Reconnect the ECM connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
2. INSPECT EFI RELAY VOLTAGE





(a) Remove the EFI relay from the engine room junction block.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:





(d) Reinstall the EFI relay.
OK -- INSPECT EFI RELAY
NG -- Continue to next step.
3. INSPECT FUSE (EFI FUSE)





(a) Inspect the EFI fuse.
(1) Remove the EFI fuse from the engine room junction block.
(2) Measure the EFI fuse resistance according to the value(s) in the table below.
Standard resistance:





(3) Reinstall the EFI fuse.
NG -- REPLACE FUSE (EFI FUSE)
OK -- CHECK AND REPAIR HARNESS AND CONNECTOR (BATTERY - EFI RELAY)
4. INSPECT EFI RELAY (P0031)

NG -- REPLACE EFI RELAY
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (EFI RELAY - ECM)





(a) Disconnect the ECM connector.





(b) Remove the EFI relay from the engine room junction block.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):





Standard resistance (Check for short):





(d) Reconnect the ECM connector.
(e) Reinstall the EFI relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
6. INSPECT ECM (IGSW VOLTAGE)





(a) Disconnect the ECM connectors.
(b) Turn the ignition switch to the ON position.
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:





(d) Reconnect the ECM connectors.
OK -- CHECK HARNESS AND CONNECTOR (EFI RELAY - ECM, EFI RELAY - BODY GROUND)
NG -- Continue to next step.
7. INSPECT FUSE (IG2 FUSE)





(a) Remove the IG2 fuse from the engine room junction block.
(b) Measure the fuse resistance according to the value(s) in the table below.
Standard resistance:





(c) Reinstall the fuse.
NG -- REPLACE FUSE (IG2 FUSE)
OK -- Continue to next step.
8. INSPECT IGNITION SWITCH ASSEMBLY





(a) Disconnect the ignition switch connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(c) Reconnect the ignition switch connector.
NG -- REPLACE IGNITION SWITCH ASSEMBLY
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR
9. CHECK HARNESS AND CONNECTOR (EFI RELAY - ECM, EFI RELAY - BODY GROUND)





(a) Disconnect the ECM connector.





(b) Remove the EFI relay from the engine room junction block.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):





Standard resistance (Check for short):





(d) Reconnect the ECM connector.
(e) Reinstall the EFI relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE ECM