Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: ECM Power Source Circuit

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Engine / A25a-fxs Engine Control / Sfi System / ECM Power Source Circuit

DESCRIPTION

When the power switch is turned to on (IG), the auxiliary battery voltage is applied to IGSW of the ECM. When the transistor in the MREL circuit operates, current flows from the auxiliary battery to ground through the drive circuit of the EFI-MAIN NO. 1 relay, thus operating the relay which supplies power to the +B and +B2 terminals of the ECM.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following 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:

Tester Connection	Condition	Specified Condition
A19-10 (E1) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

2.	CHECK TERMINAL VOLTAGE (IGSW TERMINAL VOLTAGE)

*a	Front view of wire harness connector (to ECM)

(a) Disconnect the ECM connector.

(b) Turn the power switch on (IG).

Standard Voltage:

Tester Connection	Condition	Specified Condition
A19-2 (IGSW) - Body ground	Power switch on (IG)	11 to 14 V

GO TO STEP 6

3.	INSPECT EFI-MAIN NO. 1 RELAY

(a) Inspect the EFI-MAIN NO. 1 relay.

Click here

REPLACE EFI-MAIN NO. 1 RELAY

4.	CHECK HARNESS AND CONNECTOR (EFI-MAIN NO. 1 RELAY - ECM)

(a) Remove the EFI-MAIN NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(b) Remove the VVT, EFI-MAIN NO. 2 and EFI-MAIN NO. 3 relays from the No. 1 engine room relay block and No. 1 junction block assembly.

HINT:

Remove the VVT, EFI-MAIN NO. 2 and EFI-MAIN NO. 3 relays connected between the checked terminals as the coil inside the relay influences the measurement value.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
2 (EFI-MAIN NO. 1 relay) - A19-15 (MREL)	Always	Below 1 Ω
5 (EFI-MAIN NO. 1 relay) - A19-9 (+B)	Always	Below 1 Ω
5 (EFI-MAIN NO. 1 relay) - A19-35 (+B2)	Always	Below 1 Ω
2 (EFI-MAIN NO. 1 relay) or A19-15 (MREL) - Body ground and other terminals	Always	10 kΩ or higher
5 (EFI-MAIN NO. 1 relay), A19-9 (+B) or A19-35 (+B2) - Body ground and other terminals	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

5.	CHECK TERMINAL VOLTAGE (POWER SOURCE OF EFI-MAIN NO. 1 RELAY)

*1	No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
*2	EFI-MAIN NO. 1 Relay

(a) Remove the EFI-MAIN NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
3 (EFI-MAIN NO. 1 relay) - Body ground	Always	11 to 14 V
1 (EFI-MAIN NO. 1 relay) - Body ground	Always	11 to 14 V

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - EFI-MAIN NO. 1 RELAY)

6.	INSPECT IG2 NO. 1 RELAY

(a) Inspect the IG2 NO. 1 relay.

Click here

REPLACE IG2 NO. 1 RELAY

7.	CHECK HARNESS AND CONNECTOR (IG2 NO. 1 RELAY - ECM)

(a) Remove the IG2 NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

(b) Disconnect the ECM connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
3 (IG2 NO. 1 relay) - A19-2 (IGSW)	Always	Below 1 Ω
3 (IG2 NO. 1 relay) or A19-2 (IGSW) - Body ground and other terminals	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

8.	CHECK TERMINAL VOLTAGE (POWER SOURCE OF IG2 NO. 1 RELAY)

*1	No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly
*2	IG2 NO. 1 Relay

(a) Remove the IG2 NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
5 (IG2 NO. 1 relay) - Body ground	Always	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR (AUXILIARY BATTERY - IG2 NO. 1 RELAY)

9.	CHECK HARNESS AND CONNECTOR (IG2 NO. 1 RELAY - BODY GROUND)

(a) Remove the IG2 NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
2 (IG2 NO. 1 relay) - Body ground	Always	Below 1 Ω

REPAIR OR REPLACE HARNESS OR CONNECTOR

10.	CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - IG2 NO. 1 RELAY)

(a) Disconnect the certification ECU (smart key ECU assembly) connector.

(b) Remove the IG2 NO. 1 relay from the No. 1 engine room relay block and No. 1 junction block assembly.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G40-17 (IG1D) - 1 (IG2 NO. 1 relay)	Always	Below 1 Ω
G40-17 (IG1D) or 1 (IG2 NO. 1 relay) - Body ground and other terminals	Always	10 kΩ or higher

GO TO SMART KEY SYSTEM

REPAIR OR REPLACE HARNESS OR CONNECTOR

Dtc Check / Clear

EVAP System

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Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: ECM Power Source Circuit

Dtc Check / Clear

EVAP System

See More:

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Toyota Avalon (XX50) 2019-2022 Service & Repair Manual