ECM Power Source Circuit

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

ECM Power Source Circuit

DESCRIPTION

When the power switch is on (IG), the battery voltage is applied to terminal IGSW of the ECM (included in the hybrid vehicle control ECU). The ECM 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 ECM.
If the power switch is turned off, the ECM 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 on (IG), voltage from the ECM's MREL terminal flows to the IGCT relay. This causes the contacts of the IGCT relay to close, which supplies power to terminal +B or +B1 of the ECM.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. INSPECT HYBRID VEHICLE CONTROL ECU (+B1, +B2 VOLTAGE)

(a) Turn the power switch on (IG).
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:

NG -- CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND)
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
2. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND)

(a) Disconnect the hybrid vehicle control ECU connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):

(c) Reconnect the hybrid vehicle control ECU connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (HYBRID VEHICLE CONTROL ECU - BODY GROUND)
OK -- Continue to next step.
3. INSPECT HYBRID VEHICLE CONTROL ECU (IGSW VOLTAGE)

(a) Turn the power switch on (IG).
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:

NG -- CHECK FUSE (IGN FUSE)
OK -- Continue to next step.
4. INSPECT HYBRID VEHICLE CONTROL ECU (MREL VOLTAGE)

(a) Turn the power switch on (IG).
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:

NG -- CHECK FUSE (IGCT NO. 2 FUSE)
OK -- REPLACE HYBRID VEHICLE CONTROL ECU
5. CHECK FUSE (IGCT NO. 2 FUSE)

(a) Remove the IGCT No. 2 fuse from the engine room relay block No. 2.
(b) Measure the IGCT No. 2 fuse resistance.
Standard resistance:
Below 1 Ohms
(c) Reinstall the IGCT No. 2 fuse.
NG -- REPLACE FUSE (IGCT NO. 2 FUSE)
OK -- Continue to next step.
6. INSPECT IGCT RELAY

(a) Remove the IGCT relay from the engine room relay block.
(b) Measure the IGCT relay resistance.
Standard resistance:

NG -- REPLACE IGCT RELAY
OK -- Continue to next step.
7. CHECK HARNESS AND CONNECTOR (IGCT RELAY- HYBRID VEHICLE CONTROL ECU)

(a) Remove the IGCT relay from the engine room relay block.
(b) Disconnect the hybrid vehicle control ECU connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:

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

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

(c) Reinstall the IGCT relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- CHECK AND REPAIR HARNESS AND CONNECTOR (TERMINAL +B OF HV CONTROL ECU - BATTERY POSITIVE TERMINAL)
9. CHECK FUSE (IGN FUSE)

(a) Remove the IGN fuse from the instrument panel junction block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(c) Reinstall the IGN fuse.
NG -- REPLACE FUSE (IGN FUSE)
OK -- Continue to next step.
10. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - IG2 RELAY)

(a) Remove the IG2 relay from the engine room relay block.
(b) Disconnect the hybrid vehicle control ECU connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:

(d) Reconnect the ECM connector.
(e) Reinstall the IG2 relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (HYBRID VEHICLE CONTROL ECU - IG2 RELAY)
OK -- Continue to next step.
11. INSPECT IG2 RELAY

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

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

(c) Reinstall the IG2 fuse
NG -- REPLACE FUSE (IG2 FUSE)
OK -- Continue to next step.
13. CHECK HARNESS AND CONNECTOR (IG2 RELAY POWER SOURCE)

(a) Remove the IG2 relay from the engine room relay block.
(b) Turn the power switch on (IG)
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:

(d) Reinstall the IG2 relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG2 RELAY - BATTERY)
OK -- Continue to next step.
14. CHECK HARNESS AND CONNECTOR (IG2 RELAY - BODY GROUND)

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

(c) Reinstall the IG2 relay.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG2 RELAY - BODY GROUND)
OK -- Continue to next step.
15. CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK - MAIN BODY ECU)

(a) Remove the IG2 relay from the engine room relay block.
(b) Remove the instrument panel junction block (main body ECU).
(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 IG2 relay.
(e) Reconnect the main body ECU connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (ENGINE ROOM RELAY BLOCK - MAIN BODY ECU)
OK -- CHECK SMART KEY SYSTEM