Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001CP2S
Model Year Start: 2019 Model: Corolla Hatchback Prod Date Range: [06/2018 - 01/2019]
Title: M20A-FKS (ENGINE CONTROL): SFI SYSTEM: ECM Power Source Circuit; 2019 MY Corolla Corolla Hatchback [06/2018 - 01/2019]

ECM Power Source Circuit

DESCRIPTION

When the engine switch is turned on (IG), the battery voltage is applied to the IGSW terminal of the ECM. The output signal from the MREL terminal of the ECM causes current to flow to the coil of the No. 1 integration relay (EFI-MAIN relay), closing the contacts of the EFI-MAIN 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 (POWER SOURCE OF NO. 1 INTEGRATION RELAY)

(a) Disconnect the No. 1 integration relay connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

1A-10 - Body ground

Always

11 to 14 V

1B-3 - Body ground

Always

11 to 14 V

1B-5 - Body ground

Always

11 to 14 V

NG

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

OK

2.

INSPECT NO. 1 INTEGRATION RELAY (EFI-MAIN RELAY, IG2 NO. 1 RELAY)

(a) Inspect the No. 1 integration relay (EFI-MAIN relay, IG2 NO. 1 relay).

Click here 2019 MY Corolla Corolla Hatchback Corolla HV GR Corolla [06/2018 - 01/2019]; POWER DISTRIBUTION: INTEGRATION RELAY: INSPECTION

NG

REPLACE NO. 1 INTEGRATION RELAY

OK

3.

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

(a) Disconnect the No. 1 integration relay connector.

(b) Disconnect the ECM connector.

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

HINT:

Remove the 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) Remove the VVT relay from No. 2 relay block assembly.

HINT:

Remove the VVT relay connected between the checked terminals as the coil inside the relay influences the measurement value.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1A-9 - A47-2 (IGSW)

Always

Below 1 Ω

1B-6 - A47-15 (MREL)

Always

Below 1 Ω

1B-4 - A47-9 (+B)

Always

Below 1 Ω

1B-4 - A47-35 (+B2)

Always

Below 1 Ω

1A-9 or A47-2 (IGSW) - Body ground and other terminals

Always

10 kΩ or higher

1B-6 or A47-15 (MREL) - Body ground and other terminals

Always

10 kΩ or higher

1B-4 or A47-9 (+B) - Body ground and other terminals

Always

10 kΩ or higher

1B-4 or A47-35 (+B2) - Body ground and other terminals

Always

10 kΩ or higher

HINT:

If a short is detected in any of the above circuits, there may be a malfunction in the circuit of a connected ECU.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

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

5.

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

(a) Disconnect the No. 1 integration relay connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

1A-8 - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.

CHECK TERMINAL VOLTAGE (IGSW TERMINAL VOLTAGE)

*a

Front view of wire harness connector

(to ECM)

(a) Disconnect the ECM connector.

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

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A47-2 (IGSW) - Body ground

Engine switch on (IG)

11 to 14 V

Result

Proceed to

OK

A

NG

B

A

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

B

7.

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

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

(b) Disconnect the No. 1 integration relay connector.

(c) Disconnect the instrument panel junction block assembly 4F connector.

HINT:

Disconnect the IG1-NO. 1, IG1-NO. 2 and IG2-NO. 2 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

I1-15 (IG1D) - 1A-7

Always

Below 1 Ω

I1-15 (IG1D) or 1A-7 - Body ground and other terminals

Always

10 kΩ or higher

OK

GO TO SMART ENTRY AND START SYSTEM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR