Component Tests and General Diagnostics

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

ECM Power Source Circuit

DESCRIPTION

When the power switch is turned on (IG), the battery voltage is applied to terminal IGSW of the hybrid vehicle control ECU. The hybrid vehicle control ECU MREL output signal causes a current to flow to the coil, closing the contacts of the IGCT relay and supplying power to terminal +B of the hybrid vehicle control ECU.
If the power switch is turned off, the hybrid vehicle control ECU holds the IGCT relay ON for a maximum of 2 seconds to allow for the initial setting of the throttle valve.
When the power switch is turned on (IG), voltage from the hybrid vehicle control ECU MREL terminal applies to the IGCT relay. This causes the contacts of the IGCT relay to close, which supplies power to terminal +B or +B1 of the hybrid vehicle control ECU.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND)




(a) Disconnect the C64 hybrid vehicle control ECU connector.
(b) Measure the resistance between the terminal and body ground.
Standard resistance:





(c) Reconnect the hybrid vehicle control ECU connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
2. CHECK ENGINE ROOM JUNCTION BLOCK (IGCT RELAY VOLTAGE)




(a) Remove the engine room J/B from the engine room R/B.
(b) Turn the power switch on (IG).
(c) Measure the voltage between the terminal and body ground.
Standard voltage:






OK -- INSPECT IGCT RELAY
NG -- Continue to next step.
3. INSPECT IGCT FUSE




(a) Remove the IGCT fuse from the engine room R/B.
(b) Measure the IGCT fuse resistance.
Standard resistance:
Below 1 Ohms
(c) Reinstall the IGCT fuse.
NG -- REPLACE IGCT FUSE
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (IGCT FUSE - BATTERY)




(a) Disconnect the positive battery terminal.
(b) Remove the IGCT fuse from the engine room R/B.
(c) Measure the resistance between the terminals.
Standard resistance (Check for open):





(d) Reinstall the IGCT fuse.
(e) Reconnect the positive battery terminal.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
5. INSPECT IGCT RELAY




(a) Remove the IGCT relay from the engine room R/B.
(b) Measure the resistance between the terminals.
Standard resistance:





(c) Reinstall the IGCT relay.
NG -- REPLACE IGCT RELAY
OK -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - IGCT RELAY)




(a) Disconnect the A61 hybrid vehicle control ECU connector.
(b) Remove the IGCT relay from the engine room R/B.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):






Standard resistance (Check for short):





(d) Reinstall the engine room R/B.
(e) Reconnect the hybrid vehicle control ECU connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. INSPECT HYBRID VEHICLE CONTROL ECU (IGSW VOLTAGE)




(a) Disconnect the A61 hybrid vehicle control ECU connector.
(b) Measure the voltage between the terminal and body ground.
Standard voltage:





(c) Reconnect the hybrid vehicle control ECU connector.
OK -- CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND)
NG -- Continue to next step.
8. INSPECT IG2 RELAY




(a) Remove the IG2 relay from the engine room R/B.
(b) Measure the resistance between the terminals.
Standard resistance:





(c) Reinstall the IG2 relay.
NG -- REPLACE IG2 RELAY
OK -- Continue to next step.
9. CHECK HARNESS AND CONNECTOR (IG2 RELAY - BODY GROUND)




(a) Remove the IG2 relay from the engine room R/B.
(b) Measure the resistance between the terminal and body ground.
Standard resistance:





(c) Reinstall the IG2 relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- GO TO SMART KEY SYSTEM
10. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND)




(a) Disconnect the A61 hybrid vehicle control ECU connector.
(b) Measure the resistance between the terminal and body ground.
Standard resistance:





(c) Reconnect the hybrid vehicle control ECU connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE HYBRID VEHICLE CONTROL ECU