Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: ECU Power Source Circuit

Toyota Corolla Cross (2022-2025) Service Manual / Drivetrain / K120 (cvt) / Continuously Variable Transaxle System / ECU Power Source Circuit

DESCRIPTION

When the ignition switch is turned to ON, auxiliary 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.

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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.

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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

Front view of wire harness connector

(to TCM)

-

-

(a) Disconnect the C80 TCM 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

C80-1 (+B) - Body ground

Ignition switch ON

11 to 14 V

(d) Connect the C80 TCM connector.

OK

CHECK FOR INTERMITTENT PROBLEMS

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NG

3.

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

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

(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) - 3 (EFI-MAIN NO. 1 Relay)

Always

Below 1 Ω

C80-1 (+B) or 3 (EFI-MAIN NO. 1 Relay) - Body ground

Always

10 kΩ or higher

(d) Connect the C80 TCM connector.

(e) Install the EFI-MAIN NO. 1 relay to the No. 1 engine room relay block assembly.

OK

GO TO ECM POWER SOURCE CIRCUIT (ENGINE CONTROL SYSTEM / SFI SYSTEM)

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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