VEHICLE STABILITY CONTROL SYSTEM 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

PROCEDURE

1. CHECK CAN COMMUNICATION SYSTEM

   
   

   1. Check if CAN communication system DTCs are output.

      Click here

      Result
      Result Proceed to DTCs are not output. A DTCs are output. B

   
   

   B

   INSPECT CAN COMMUNICATION SYSTEM Click here

   A

2. CHECK IF BRAKE ACTUATOR ASSEMBLY CONNECTOR IS SECURELY CONNECTED

   
   

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

      OK
      The connector is securely connected.

      Result
      Proceed to OK NG

   
   

   NG

   CONNECT CONNECTOR TO ECU CORRECTLY

   OK

3. CHECK BATTERY

   
   

   1. Check the battery voltage.

      Standard Voltage
      11 to 14 V

      Result
      Result Proceed to OK A NG (for 8NR-FTS) B NG (for 3ZR-FAE) C

   
   

   B

   CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY Click here

   C

   CHECK OR REPLACE CHARGING SYSTEM COMPONENT OR BATTERY Click here

   A

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

   
   
   1. 

      *a	Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

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

   2. 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

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

   OK

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

   
   
   1. 

      *a	Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

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

   2. 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

      Result
      Result Proceed to OK A NG (w/ Stop and Start System) B NG (w/o Stop and Start System) C

   
   

   B

   GO TO STOP AND START SYSTEM Click here

   C

   REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

   A

6. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

   
   
   1. 

      *a	Front view of wire harness connector (to Skid Control ECU (Brake Actuator Assembly))

      Turn the ignition switch off.

   2. 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

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

   OK

7. INSPECT BRAKE FLUID LEVEL WARNING SWITCH

   
   
   1. 

      *a	Component without harness connected (Brake Fluid Level Warning Switch (Brake Master Cylinder Reservoir Sub-assembly))

      Turn the ignition switch off.

   2. Remove the reservoir filler cap and strainer.

   3. Disconnect the A60 brake fluid level warning switch connector.

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

      Tech Tips

      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

      Tech Tips

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

      Result
      Result Proceed to OK A NG (for LHD) B NG (for RHD) C

   
   

   B

   REPLACE BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY Click here

   C

   REPLACE BRAKE MASTER CYLINDER RESERVOIR SUB-ASSEMBLY Click here

   A

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

   
   

   1. Disconnect the F4 combination meter assembly connector.

   2. 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

      Result
      Result Proceed to OK (w/ Vacuum Warning Switch) A OK (w/o Vacuum Warning Switch) B NG C

   
   

   B

   GO TO STEP 10 Click here

   C

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   A

9. INSPECT VACUUM WARNING SWITCH ASSEMBLY

   
   

   1. Inspect the vacuum warning switch assembly.

      Click here

      OK
      The vacuum warning switch assembly is normal.

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE VACUUM WARNING SWITCH ASSEMBLY

   OK

10. CHECK HARNESS AND CONNECTOR (BRAKE WARNING LIGHT CIRCUIT)

    
    

    1. Disconnect the F5 combination meter connector.

    2. 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

       Result
       Proceed to OK NG

    
    

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

11. READ VALUE USING GTS (BRAKE WARNING LIGHT)

    
    

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

    2. Select the Data List on the GTS.

       Click here

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

       Tester Display
       Brake Warning Light

    3. Check the GTS display condition of the brake system warning light (red indicator).

       Result
       Result Proceed to ON is displayed. (for LHD) A ON is displayed. (for RHD) B OFF is displayed. C

    
    

    A

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    C

    INSPECT METER / GAUGE SYSTEM Click here