Brake Warning Light Remains ON

BRAKE CONTROL: ELECTRONICALLY CONTROLLED BRAKE SYSTEM: Brake Warning Light Remains ON

Brake Warning Light Remains ON

DESCRIPTION

The skid control ECU is connected to the combination meter via CAN communication.
If any of the following is detected, the BRAKE warning light remains on:

- The skid control ECU connector is disconnected from the skid control ECU.
- The brake fluid level is insufficient.
- The parking brake is applied.
- EBD operation is not possible.

WIRING DIAGRAM





INSPECTION PROCEDURE
NOTICE: When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration Initialization.

PROCEDURE

1. CHECK DTC
(a) Check if the ABS, VSC and/or Electronically Controlled Brake DTC is output Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- REPAIR CIRCUIT INDICATED BY OUTPUT DTC
A -- Continue to next step.
2. CHECK CAN COMMUNICATION SYSTEM
(a) Check if the CAN communication system DTC is output Diagnosis System.
Result:






B -- INSPECT CAN COMMUNICATION SYSTEM
A -- Continue to next step.
3. CHECK IF SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED
(a) Check if the skid control ECU connector is securely connected.
OK:
The connector should be securely connected.
NG -- CONNECT CONNECTOR TO ECU CORRECTLY
OK -- Continue to next step.
4. CHECK AUXILIARY BATTERY
(a) Check the auxiliary battery voltage.
Standard voltage:
11 to 14 V
NG -- CHARGE OR REPLACE AUXILIARY BATTERY
OK -- Continue to next step.
5. INSPECT SKID CONTROL ECU (IG1 TERMINAL)




(a) Disconnect the skid control ECU connector.
(b) Turn the power switch on (IG).
(c) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)
OK -- Continue to next step.
6. INSPECT SKID CONTROL ECU (GND TERMINAL)




(a) Turn the power switch off.
(b) Disconnect the skid control ECU connectors.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)
OK -- Continue to next step.
7. READ VALUE USING TECHSTREAM (PARKING BRAKE SWITCH)
(a) Reconnect the skid control ECU connectors.
(b) Connect Techstream to the DLC3.
(c) Turn the power switch on (IG).
(d) Select the Data List mode on Techstream.

ABS / VSC / TRAC:





(e) Using Techstream, check the input of switch operation when the parking brake pedal is operated.
OK:
When the parking brake is operated, the display changes as shown above.
OK -- INSPECT COMBINATION METER ASSEMBLY
NG -- Continue to next step.
8. INSPECT PARKING BRAKE SWITCH




(a) Turn the power switch off.
(b) Disconnect the parking brake switch connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE PARKING BRAKE SWITCH
OK -- Continue to next step.
9. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - PARKING BRAKE SWITCH)




(a) Disconnect the main body ECU connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:





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

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)
10. INSPECT COMBINATION METER ASSEMBLY
(a) Turn the power switch off.
(b) Perform Active Test of the combination meter (meter CPU) using Techstream Scan Tool Testing and Procedures.
OK:
The BRAKE warning light turns on or off in accordance with Techstream.
HINT: If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step before replacing the part Problem Symptoms Table.

NG -- REPLACE COMBINATION METER ASSEMBLY
OK -- REPLACE SKID CONTROL ECU