Toyota CH-R Service Manual: Brake Warning Light Remains ON

DESCRIPTION

The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication.

If any of the following is detected, the brake system warning light (red indicator) remains on:

  • The skid control ECU (brake actuator assembly) connector is disconnected from the skid control ECU (brake actuator assembly).
  • The brake fluid level is insufficient.
  • The vacuum inside the brake booster decreases. (w/ Vacuum Warning Switch)
  • EBD operation is not possible.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • When replacing the skid control ECU (brake actuator assembly), perform system variant learning.

    Click here

  • Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

1.

CHECK CAN COMMUNICATION SYSTEM

(a) Check if CAN communication system DTCs are output.

Click here

Result

Proceed to

DTCs are not output.

A

DTCs are output.

B

B

INSPECT CAN COMMUNICATION SYSTEM

A

2.

CHECK IF BRAKE ACTUATOR ASSEMBLY CONNECTOR IS SECURELY CONNECTED

(a) Check if the skid control ECU (brake actuator assembly) connector is securely connected.

OK:

The connector is securely connected.

NG

CONNECT CONNECTOR TO ECU CORRECTLY

OK

3.

CHECK BATTERY

(a) Check the battery voltage.

Standard Voltage:

11 to 14 V

NG

CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY

OK

4.

CHECK HARNESS AND CONNECTOR (POWER SOURCE (+BS) TERMINAL)

(a) Disconnect the A42 skid control ECU (brake actuator assembly) connector.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A42-30 (+BS) - Body ground

Always

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK

5.

CHECK HARNESS AND CONNECTOR (POWER SOURCE (IG1) TERMINAL)

(a) Disconnect the A42 skid control ECU (brake actuator assembly) connector.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A42-36 (IG1) - Body ground

Ignition switch ON

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

OK

6.

CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

(a) Turn the ignition switch off.

*a

Front view of wire harness connector

(to Skid Control ECU (Brake Actuator Assembly))

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

A42-46 (GND1) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

OK

7.

INSPECT BRAKE FLUID LEVEL WARNING SWITCH

(a) Turn the ignition switch off.

*a

Component without harness connected

(Brake Fluid Level Warning Switch (Brake Master Cylinder Reservoir Sub-assembly))

(b) Remove the reservoir filler cap and strainer.

(c) Disconnect the A60 brake fluid level warning switch connector.

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

HINT:

A float is located inside the reservoir. Its position changes according to the brake fluid level.

Standard Resistance:

Tester Connection

Condition

Specified Condition

1 (+) - 2 (E)

Switch OFF (Float up)

1.9 to 2.1 kΩ

1 (+) - 2 (E)

Switch ON (Float down)

Below 1 Ω

HINT:

If there is no problem after finishing the above check, adjust the brake fluid level to the MAX level.

NG

REPLACE BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY

OK

8.

CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE FLUID LEVEL WARNING SWITCH)

(a) Disconnect the F4 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

F4-12 (SW) - A60-1 (+)

Always

Below 1 Ω

F4-12 (SW) or A60-1 (+) - Body ground

Always

10 kΩ or higher

A60-2 (E) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

9.

INSPECT VACUUM WARNING SWITCH ASSEMBLY

(a) Inspect the vacuum warning switch assembly.

Click here

OK:

The vacuum warning switch assembly is normal.

NG

REPLACE VACUUM WARNING SWITCH ASSEMBLY

OK

10.

CHECK HARNESS AND CONNECTOR (BRAKE WARNING LIGHT CIRCUIT)

(a) Disconnect the F5 combination meter connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

F5-2 (VCM) - A31-2 (+)

Always

Below 1 Ω

F5-2 (VCM) or A31-2 (+) - Body ground

Always

10 kΩ or higher

A31-1 (E) - Body ground

Always

Below 1 Ω

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

11.

READ VALUE USING TECHSTREAM (BRAKE WARNING LIGHT)

(a) Reconnect the A41 skid control ECU (brake actuator assembly) connector.

(b) Select the Data List on the Techstream.

Click here

Chassis > ABS/VSC/TRAC/EPB > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Brake Warning Light

Brake system warning light (red indicator)

ON or OFF

ON: Warning light on

OFF: Warning light off

-

Chassis > ABS/VSC/TRAC/EPB > Data List

Tester Display

Brake Warning Light

(c) Check the Techstream display condition of the brake system warning light (red indicator).

Result

Proceed to

ON is displayed.

A

OFF is displayed.

B

A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

INSPECT METER / GAUGE SYSTEM

    ABS Warning Light does not Come ON
    DESCRIPTION The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication. CAUTION / NOTICE / HINT NOTICE: When replacing the skid control E ...

    Brake Warning Light does not Come ON
    DESCRIPTION The skid control ECU (brake actuator assembly) is connected to the combination meter assembly via CAN communication. CAUTION / NOTICE / HINT NOTICE: When replacing the skid c ...

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