Last Modified: 05-13-2024 6.11:8.1.0 Doc ID: RM100000001D0YQ
Model Year Start: 2019 Model: Corolla Hatchback Prod Date Range: [06/2018 - 09/2022]
Title: K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: ECU Power Source Circuit; 2019 - 2022 MY Corolla Corolla Hatchback [06/2018 - 09/2022]

ECU Power Source Circuit

DESCRIPTION

When the engine switch is turned on (IG), battery voltage is applied to terminal MREL of the ECM through the coil of the EFI-MAIN relay. This causes the EFI-MAIN relay to close, which supplies power to terminal +B of the TCM.

WIRING DIAGRAM

Refer to DTC U010087.

Click here 2019 - 2022 MY Corolla Corolla Hatchback [06/2018 - 09/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: U010087; Lost Communication with ECM/PCM "A" Missing Message

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • Perform registration and/or initialization when parts related to the continuously variable transaxle system are replaced.

    Click here 2019 MY Corolla Corolla Hatchback [06/2018 - 01/2019]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: PRECAUTION 2020 - 2022 MY Corolla Corolla Hatchback [01/2019 - 09/2022]; K120 / K121 (CVT): K120 CONTINUOUSLY VARIABLE TRANSAXLE SYSTEM: PRECAUTION

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (TCM - BODY GROUND)

(a) Disconnect the C80 TCM connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

C80-2 (E1) - Body ground

Always

Below 1 Ω

(c) Connect the C80 TCM connector.

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.

INSPECT ECU TERMINAL VOLTAGE (+B TERMINAL)

(a) Disconnect the C80 TCM 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

C80-1 (+B) - Body ground

Engine switch on (IG)

11 to 14 V

(d) Connect the C80 TCM connector.

OK

CHECK FOR INTERMITTENT PROBLEMS

NG

3.

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

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

(b) Disconnect the C80 TCM connector.

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

Standard Resistance (Check for Open):

Tester Connection

Condition

Specified Condition

C80-1 (+B) - 1B-4

Always

Below 1 Ω

C80-1 (+B) or 1B-4 - Body ground

Always

10 kΩ or higher

(d) Connect the C80 TCM connector.

(e) Connect the 1B No. 1 integration relay connector.

OK

GO TO ECM POWER SOURCE CIRCUIT (ENGINE CONTROL SYSTEM / SFI SYSTEM) 2019 MY Corolla Corolla Hatchback [06/2018 - 01/2019]; M20A-FKS (ENGINE CONTROL): SFI SYSTEM: ECM Power Source Circuit 2020 - 2022 MY Corolla Corolla Hatchback [01/2019 - 09/2022]; M20A-FKS (ENGINE CONTROL): SFI SYSTEM: ECM Power Source Circuit

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR