Last Modified: 08-21-2023 6.11:8.1.0 Doc ID: RM100000001A0G5
Model Year Start: 2019 Model: Avalon HV Prod Date Range: [04/2018 - 08/2020]
Title: HYBRID / BATTERY CONTROL: HYBRID CONTROL SYSTEM (for NICKEL METAL HYDRIDE BATTERY): ECU Power Source Circuit; 2019 - 2020 MY Avalon HV [04/2018 - 08/2020]

ECU Power Source Circuit

DESCRIPTION

If the power switch is on (IG), the hybrid vehicle control ECU applies current to the MREL terminal to turn the IGCT relay on. This supplies power to the +B1 and +B2 terminals.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary battery terminal notices before proceeding with work.

Click here 2019 - 2022 MY Avalon Avalon HV [04/2018 -        ]; INTRODUCTION: REPAIR INSTRUCTION: PRECAUTION

PROCEDURE

1.

CHECK 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:

Tester Connection

Condition

Specified Condition

A24-4 (+B1) - Body ground

Power switch on (IG)

11 to 14 V

A23-1 (+B2) - Body ground

Power switch on (IG)

11 to 14 V

*a

Component with harness connected

(Hybrid Vehicle Control ECU)

(c) Turn the power switch off.

NG

GO TO STEP 3

OK

2.

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

(a) Disconnect the G46 and G47 hybrid vehicle control ECU connectors.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

G46-6 (E1) - Body ground

Always

Below 1 Ω

G46-5 (E01) - Body ground

Always

Below 1 Ω

G47-5 (E02) - Body ground

Always

Below 1 Ω

G47-4 (E12) - Body ground

Always

Below 1 Ω

*a

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

(c) Reconnect the G46 and G47 hybrid vehicle control ECU connectors.

OK

GO TO PROBLEM SYMPTOMS TABLE

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

3.

CHECK 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:

Tester Connection

Condition

Specified Condition

A24-6 (MREL) - Body ground

Power switch on (IG)

11 to 14 V

*a

Component with harness connected

(Hybrid Vehicle Control ECU)

(c) Turn the power switch off.

NG

REPLACE HYBRID VEHICLE CONTROL ECU

OK

4.

CHECK FUSE (PM-IGCT)

(a) Remove the PM-IGCT fuse from the No. 4 relay block.

*1

No. 4 Relay Block

*2

PM-IGCT Fuse

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

PM-IGCT fuse

Always

Below 1 Ω

(c) Install the PM-IGCT fuse.

NG

GO TO STEP 12

OK

5.

CHECK FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE)

(a) Disconnect the cable from the negative (-) auxiliary battery terminal.

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

(c) Disconnect the 7B fusible link block assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

7B-1 - A-1 (Positive (+) auxiliary battery terminal)

Power switch off

Below 1 Ω

*1

Fusible Link Block Assembly

*a

Component without harness connected

(Fusible Link Block Assembly)

(e) Reconnect the 7B fusible link block assembly connector.

(f) Reconnect the cable to the positive (+) auxiliary battery terminal.

(g) Reconnect the cable to the negative (-) auxiliary battery terminal.

NG

GO TO STEP 13

OK

6.

INSPECT RELAY (IGCT)

(a) Remove the IGCT relay from the No. 3 relay block.

*1

No. 3 Relay Block

*2

IGCT Relay

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3 - 5

Auxiliary battery voltage not applied between terminals 1 and 2

10 kΩ or higher

Auxiliary battery voltage applied between terminals 1 and 2

Below 1 Ω

*1

IGCT Relay

(c) Install the IGCT relay.

NG

REPLACE RELAY (IGCT)
OK

7.

CHECK HARNESS AND CONNECTOR (NO. 4 RELAY BLOCK - HYBRID VEHICLE CONTROL ECU)

(a) Disconnect the A23 and A24 hybrid vehicle control ECU connectors.

(b) Remove the PM-IGCT fuse from the No. 4 relay block.

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

*1

No. 4 Relay Block

*2

PM-IGCT Fuse Holder

*a

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

A24-4 (+B1) - 2 (PM-IGCT fuse holder)

Always

Below 1 Ω

A23-1 (+B2) - 2 (PM-IGCT fuse holder)

Always

Below 1 Ω

(d) Reconnect the A23 and A24 hybrid vehicle control ECU connectors.

(e) Install the PM-IGCT fuse.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

8.

CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - NO. 4 RELAY BLOCK)

(a) Remove the IGCT relay from the No. 3 relay block.

(b) Remove the PM-IGCT fuse from the No. 4 relay block.

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

*1

No. 3 Relay Block

*2

No. 4 Relay Block

*3

IGCT Relay Holder

*4

PM-IGCT Fuse Holder

Standard Resistance:

Tester Connection

Condition

Specified Condition

5 (IGCT relay holder) - 1 (PM-IGCT fuse holder)

Always

Below 1 Ω

(d) Install the PM-IGCT fuse.

(e) Install the IGCT relay.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

9.

CHECK HARNESS AND CONNECTOR (FUSIBLE LINK BLOCK ASSEMBLY - NO. 3 RELAY BLOCK)

(a) Disconnect the 7B fusible link block assembly connector.

(b) Remove the IGCT relay from the No. 3 relay block.

*1

No. 3 Relay Block

*2

IGCT Relay Holder

*a

Front view of wire harness connector

(to Fusible Link Block Assembly)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3 (IGCT relay holder) - 7B-1

Always

Below 1 Ω

(d) Install the IGCT relay.

(e) Reconnect the 7B fusible link block assembly connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

10.

CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU - NO. 3 RELAY BLOCK)

(a) Disconnect the A24 hybrid vehicle control ECU connector.

(b) Remove the IGCT relay from the No. 3 relay block.

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

*1

No. 3 Relay Block

*2

IGCT Relay Holder

*a

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

A24-6 (MREL) - 1 (IGCT relay holder)

Always

Below 1 Ω

A24-6 (MREL) or 1 (IGCT relay holder) - Body ground and other terminals

Always

10 kΩ or higher

(d) Install the IGCT relay.

(e) Reconnect the A24 hybrid vehicle control ECU connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

11.

CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - BODY GROUND)

(a) Remove the IGCT relay from the No. 3 relay block.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

2 (IGCT relay holder) - Body ground

Always

Below 1 Ω

*1

No. 3 Relay Block

*2

IGCT Relay Holder

(c) Install the IGCT relay.

OK

CHECK FOR INTERMITTENT PROBLEMS

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

12.

CHECK HARNESS AND CONNECTOR (NO. 4 RELAY BLOCK - HYBRID VEHICLE CONTROL ECU)

(a) Remove the PM-IGCT fuse from the No. 4 relay block.

(b) Disconnect the A23 and A24 hybrid vehicle control ECU connectors.

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

*1

No. 4 Relay Block

*2

PM-IGCT Fuse Holder

*a

Rear view of wire harness connector

(to Hybrid Vehicle Control ECU)

-

-

Standard Resistance:

Tester Connection

Condition

Specified Condition

A24-4 (+B1) or 2 (PM-IGCT fuse holder) - Body ground and other terminals

Always

10 kΩ or higher

A23-1 (+B2) or 2 (PM-IGCT fuse holder) - Body ground and other terminals

Always

10 kΩ or higher

(d) Reconnect the A23 and A24 hybrid vehicle control ECU connectors.

(e) Install the PM-IGCT fuse.

OK

REPLACE FUSE (PM-IGCT)
NG

GO TO STEP 15

13.

CHECK HARNESS AND CONNECTOR (FUSIBLE LINK BLOCK ASSEMBLY - NO. 3 RELAY BLOCK)

(a) Disconnect the 7B fusible link block assembly connector.

(b) Remove the IGCT relay from the No. 3 relay block.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3 (IGCT relay holder) or 7B-1 - Body ground and other terminals

Always

10 kΩ or higher

*1

No. 3 Relay Block

*2

IGCT Relay Holder

*a

Front view of wire harness connector

(to Fusible Link Block Assembly)

(d) Install the IGCT relay.

(e) Reconnect the 7B fusible link block assembly connector.

NG

GO TO STEP 16

OK

14.

CHECK HARNESS AND CONNECTOR (NO. 3 RELAY BLOCK - NO. 4 RELAY BLOCK)

(a) Remove the IGCT relay from the No. 3 relay block.

(b) Remove the PM-IGCT fuse from the No. 4 relay block.

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

*1

No. 3 Relay Block

*2

No. 4 Relay Block

*3

IGCT Relay Holder

*4

PM-IGCT Fuse Holder

Standard Resistance:

Tester Connection

Condition

Specified Condition

5 (IGCT relay holder) or 1 (PM-IGCT fuse holder) - Body ground and other terminals

Always

10 kΩ or higher

(d) Install the PM-IGCT fuse.

(e) Install the IGCT relay.

OK

REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE)
NG

GO TO STEP 17

15.

REPAIR OR REPLACE HARNESS OR CONNECTOR
NEXT

REPLACE FUSE (PM-IGCT)

16.

REPAIR OR REPLACE HARNESS OR CONNECTOR
NEXT

REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE)

17.

REPAIR OR REPLACE HARNESS OR CONNECTOR
NEXT

REPLACE FUSIBLE LINK BLOCK ASSEMBLY (IGCT FUSE)