Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM1000000028LUO
Model Year Start: 2023 Model: Corolla Hatchback Prod Date Range: [11/2022 - 03/2023]
Title: M20A-FKS (ENGINE CONTROL): SFI SYSTEM: ECM Power Source Circuit; 2023 MY Corolla Corolla Hatchback [11/2022 - 03/2023]

ECM Power Source Circuit

DESCRIPTION

When the ignition switch is turned to ON, the battery voltage is applied to the IGP terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the EFI-MAIN NO. 1 relay, closing the contacts of the EFI-MAIN NO. 1 relay and supplying power to terminals +B and +B2 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

A47-10 (E1) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.

CHECK TERMINAL VOLTAGE (IGP TERMINAL VOLTAGE)

(a) Disconnect the ECM connector.

(b) Turn the ignition switch to ON.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A47-2 (IGP) - Body ground

Ignition switch ON

11 to 14 V

*a

Front view of wire harness connector

(to ECM)

NG

GO TO STEP 6

OK

3.

INSPECT EFI-MAIN NO. 1 RELAY

Click here 2023 - 2025 MY Corolla Corolla Hatchback [11/2022 -        ]; M20A-FKS (ENGINE CONTROL): RELAY: ON-VEHICLE INSPECTION+

NG

REPLACE EFI-MAIN NO. 1 RELAY

OK

4.

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

(a) Disconnect the ECM connector.

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

HINT:

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

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1(EFI-MAIN NO.1 relay) - A47-15 (MREL)

Always

Below 1 Ω

3(EFI-MAIN NO.1 relay) - A47-9 (+B)

Always

Below 1 Ω

3(EFI-MAIN NO.1 relay) - A47-35 (+B2)

Always

Below 1 Ω

1(EFI-MAIN NO.1 relay) or A47-15 (MREL) - Body ground and other terminals

Always

10 kΩ or higher

3(EFI-MAIN NO.1 relay), A47-9(+B) or A47-35 (+B2) - Body ground and other terminals

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

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

2(EFI-MAIN NO. 1 relay) - Body ground

Always

11 to 14 V

5(EFI-MAIN NO. 1 relay) - Body ground

Always

11 to 14 V

OK

REPLACE ECM

NG

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

6.

INSPECT IGP-MAIN RELAY

Click here 2023 - 2025 MY Corolla Corolla Hatchback [11/2022 -        ]; M20A-FKS (ENGINE CONTROL): RELAY: ON-VEHICLE INSPECTION

NG

REPLACE IGP-MAIN RELAY

OK

7.

CHECK HARNESS AND CONNECTOR (IGP-MAIN RELAY - ECM)

(a) Disconnect the ECM connector.

(b) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3(IGP-MAIN relay) - A47-2 (IGP)

Always

Below 1 Ω

3(IGP-MAIN relay) or A47-2 (IGP) - Body ground and other terminals

Always

10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

8.

CHECK HARNESS AND CONNECTOR (POWER SOURCE VOLTAGE OF IGP-MAIN RELAY)

*1

No. 1 Engine Room Relay Block and No. 1 Junction Block Assembly

*2

IGP-MAIN Relay

(a) Remove the IGP-MAIN 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(IGP-MAIN relay) - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGP-MAIN RELAY)

OK

9.

CHECK HARNESS AND CONNECTOR (IGP-MAIN RELAY - BODY GROUND)

(a) Remove the IGP-MAIN 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

1(IGP-MAIN relay) - Body ground

Always

Below 1 Ω

Result

Proceed to

OK (w/ Smart Key System)

A

OK (w/o Smart Key System)

B

NG

C

B

GO TO STEP 11

C

REPAIR OR REPLACE HARNESS OR CONNECTOR

A

10.

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - IGP-MAIN RELAY)

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

(b) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

O175-24 (IGPD) - 2(IGP-MAIN relay)

Always

Below 1 Ω

O175-24 (IGPD) or 2(IGP-MAIN relay) - Body ground and other terminals

Always

10 kΩ or higher

OK

GO TO SMART KEY SYSTEM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

11.

INSPECT IGNITION OR STARTER SWITCH ASSEMBLY

(a) Inspect the ignition or starter switch assembly.

Click here 2020 - 2025 MY Corolla Corolla Hatchback [01/2019 -        ]; M20A-FKS (STARTING): IGNITION SWITCH: INSPECTION

NG

REPLACE IGNITION OR STARTER SWITCH ASSEMBLY

OK

12.

CHECK HARNESS AND CONNECTOR (IGNITION OR STARTER SWITCH ASSEMBLY - IGP-MAIN RELAY)

(a) Disconnect the ignition or starter switch assembly connector.

(b) Remove the IGP-MAIN relay from the No. 1 engine room relay block and No. 1 junction block assembly.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

I12-8 (IG1) - 2 (IGP-MAIN relay)

Always

Below 1 Ω

I12-8 (IG1) or 2 (IGP-MAIN relay) - Body ground and other terminals

Always

10 kΩ or higher

OK

REPAIR OR REPLACE HARNESS OR CONNECTOR (BATTERY - IGNITION OR STARTER SWITCH ASSEMBLY)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR