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 and multiplex communications.
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.
- The EBD is defective.

WIRING DIAGRAM





INSPECTION PROCEDURE
NOTE: 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 CODE
A -- Continue to next step.
2. INSPECT CAN COMMUNICATION SYSTEM
(a) Check if the CAN communication system DTC is output Diagnosis System.
Result:






B -- REPAIR CAN COMMUNICATION SYSTEM
A -- Continue to next step.
3. INSPECT MULTIPLEX COMMUNICATION SYSTEM
(a) Check if the multiplex communication system DTC is output Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- REPAIR MULTIPLEX COMMUNICATION SYSTEM
A -- Continue to next step.
4. INSPECT IF SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED
(a) Check the skid control ECU connector's connection.
OK:
The connector should be securely connected.
NG -- CONNECT CONNECTOR TO ECU CORRECTLY
OK -- Continue to next step.
5. INSPECT BATTERY
(a) Check the battery voltage.
Voltage:
11 to 14 V
NG -- INSPECT CHARGING SYSTEM
OK -- Continue to next step.
6. INSPECT SKID CONTROL ECU (IG1 TERMINAL)





(a) Turn the ignition switch on.
(b) Measure the voltage according to the value(s) in the table below.
Voltage:






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





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






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)
OK -- Continue to next step.
8. READ VALUE OF TECHSTREAM (PARKING BRAKE SWITCH)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch on.
(c) Select the Data List mode on Techstream.

ABS / VSC / TRAC:





(d) Using Techstream, check the input of switch operation when the parking brake pedal is operated.
OK:
When the parking brake pedal is operated, the display changes as shown above.
NG -- INSPECT PARKING BRAKE SWITCH
OK -- Continue to next step.
9. INSPECT COMBINATION METER ASSEMBLY
(a) Check the combination meter assembly How To Proceed With Troubleshooting.
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
10. INSPECT PARKING BRAKE SWITCH





(a) Disconnect the parking brake switch connector.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPLACE PARKING BRAKE SWITCH
OK -- Continue to next step.
11. CHECK HARNESS AND CONNECTOR (BETWEEN PARKING BRAKE SWITCH AND SKID CONTROL ECU)





(a) Disconnect the skid control ECU connector S40 and parking brake switch connector.
(b) Measure the resistance according to the value(s) in the table below.
Resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE SKID CONTROL ECU