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 warning light 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.

• EBD operation is not possible.

• The vacuum inside the brake booster decreases.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

PROCEDURE

1. CHECK IF SKID CONTROL ECU 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

2. CHECK CAN COMMUNICATION SYSTEM

   
   

   1. Check if CAN communication system DTCs are output.

      for LHD: Click here

      for RHD: Click here

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

   
   

   B

   CHECK CAN COMMUNICATION SYSTEM for LHD: Click here CHECK CAN COMMUNICATION SYSTEM for RHD: Click here

   A

3. INSPECT BATTERY

   
   

   1. Check the battery voltage.

      Standard voltage
      11 to 14 V

      Result
      Proceed to OK NG

   
   

   NG

   CHECK OR REPLACE CHARGING SYSTEM OR BATTERY for 2AR-FE: Click here CHECK OR REPLACE CHARGING SYSTEM OR BATTERY for 2GR-FE (w/ Battery Current Sensor): Click here CHECK OR REPLACE CHARGING SYSTEM OR BATTERY for 2GR-FE (w/o Battery Current Sensor): : Click here

   OK

4. CHECK TERMINAL VOLTAGE (IG1 TERMINAL)

   
   
   1. 

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

      Disconnect the A50 skid control ECU (brake actuator assembly) connector.

   2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition A50-12 (IG1) - Body ground Engine switch on (IG) 10.5 to 16 V

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

   
   

   B

   INSPECT STOP AND START SYSTEM (BACKUP BOOST CONVERTER CIRCUIT) Click here

   C

   REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)

   A

5. CHECK HARNESS AND CONNECTOR (GND1 TERMINAL)

   
   

   1. Turn the engine switch off.

   2. 

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

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

      Standard Resistance
      Tester Connection Condition Specified Condition A50-25 (GND1) - Body ground Always Below 1 Ω

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR (GND1 CIRCUIT)

   OK

6. INSPECT BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY

   
   
   1. 

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

      Turn the engine switch off.

   2. Remove the reservoir filler cap and strainer.

   3. Disconnect the A18 brake fluid level warning switch (brake master cylinder reservoir assembly) 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 can be changed by increasing or decreasing the level of brake fluid.

      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
      Proceed to OK NG

   
   

   NG

   REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY for LHD: Click here REPLACE BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY for RHD: Click here

   OK

7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE MASTER CYLINDER RESERVOIR ASSEMBLY)

   
   

   1. Disconnect the G16 combination meter assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition G16-31 (B/LE) - A18-1 (+) Always Below 1 Ω G16-31 (B/LE) or A18-1 (+) - Body ground Always 10 kΩ or higher A18-2 (E) - Body ground Always Below 1 Ω

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

8. READ VALUE USING GTS (BRAKE WARNING LIGHT)

   
   

   1. Reinstall the reservoir filler cap and strainer.

   2. Reconnect the G16 combination meter assembly connector and the A18 brake fluid level warning switch (brake master cylinder reservoir assembly) connector.

   3. Reconnect the A50 skid control ECU (brake actuator assembly) connector.

   4. Connect the GTS to the DLC3.

   5. Turn the engine switch on (IG).

   6. Turn the GTS on.

   7. Select the Data List using the GTS.

      Click here

      
      Chassis > ABS/VSC/TRC > Data List

      Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
      Brake Warning Light	Brake warning light	ON or OFF	ON: Warning light on OFF: Warning light off	-

      
      Chassis > ABS/VSC/TRC > Data List

      Tester Display
      Brake Warning Light

   8. Check the GTS display condition of the brake warning light.

      Result
      Result Proceed to Display of the Data List remains OFF. A Display of the Data List remains ON. B

      Tech Tips

      If troubleshooting has been carried out according to Problem Symptoms Table, refer back to the table and proceed to the next step before replacing parts.

      Click here

   
   

   A

   INSPECT METER / GAUGE SYSTEM Click here

   B

   REPLACE BRAKE ACTUATOR ASSEMBLY Click here