RX400h · Service Manual BRAKE

Brake Warning Light Remains ON

Circuit diagnosis

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:
  1. The skid control ECU connector is disconnected from the skid control ECU.
  2. The brake fluid level is insufficient.
  3. The parking brake is applied.
  4. The EBD is defective.

WIRING DIAGRAM

C112008E03

INSPECTION PROCEDURE

NOTICE:
When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration (Click here).


1. CHECK DTC

  1. Check if the ABS, VSC and/or ECB DTC is output (Click here).

    Result:
    Condition
    		 Proceed To
    DTC is not output
    		 A
    DTC is output
    		 B



B
REPAIR CIRCUIT INDICATED BY OUTPUT CODE
A


2. INSPECT CAN COMMUNICATION SYSTEM

  1. Check if the CAN communication system DTC is output (Click here for LHD, for Click here RHD).

    Result:
    Condition
    		 Proceed To
    DTC is not output
    		 A
    DTC is output
    		 B



B
REPAIR CAN COMMUNICATION SYSTEM
A


3. INSPECT MULTIPLEX COMMUNICATION SYSTEM

  1. Check if the multiplex communication system DTC is output (Click here).

    Result:
    Condition
    		 Proceed To
    DTC is not output
    		 A
    DTC is output
    		 B



B
REPAIR MULTIPLEX COMMUNICATION SYSTEM
A


4. INSPECT IF SKID CONTROL ECU CONNECTOR IS SECURELY CONNECTED

  1. Check the skid control ECU connector's connection.

    OK:
    The connector should be securely connected.



 NG
CONNECT CONNECTOR TO ECU CORRECTLY
OK


5. INSPECT BATTERY

  1. Check the battery voltage.

    Voltage:
    11 to 14 V



 NG
INSPECT CHARGING SYSTEM
OK


6. INSPECT SKID CONTROL ECU (IG1 TERMINAL)

  1. F047485E35
    Turn the ignition switch on.

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

    Voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    S40-7 (IG1) - Body ground
    		 Ignition switch on
    		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 CIRCUIT)
OK


7. INSPECT SKID CONTROL ECU (GND TERMINAL)

  1. F047485E34
    Measure the resistance according to the value(s) in the table below.

    Resistance:
    Tester Connection
    		 Specified Condition
    S41-1 (GND1) - Body ground
    		 Below 1 Ω
    S40-2 (GND2) - Body ground
    		 Below 1 Ω
    S40-1 (GND3) - Body ground
    		 Below 1 Ω
    S39-2 (GND4) - Body ground
    		 Below 1 Ω
    S39-1 (GND5) - Body ground
    		 Below 1 Ω
    S38-4 (GND6) - Body ground
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (GND CIRCUIT)
OK


8. READ VALUE OF INTELLIGENT TESTER (PARKING BRAKE SWITCH)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch on.

  1. Select the DATA LIST mode on the intelligent tester.

    ABS / VSC / TRAC: 
    Item (Display)
    		 Measurement Item/Range (Display)
    		 Normal Condition
    PARKING BRAKE SW
    		 Parking brake switch/ON or OFF
    		 ON: Parking brake pedal depressed
    OFF: Parking brake pedal released

  1. Using the intelligent tester, 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
Go to step 10
OK


9. INSPECT COMBINATION METER ASSEMBLY

  1. Check the combination meter assembly (Click here).

    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 (Click here).



 NG
REPLACE COMBINATION METER ASSEMBLY
OK

REPLACE SKID CONTROL ECU

10. INSPECT PARKING BRAKE SWITCH

  1. F050267E01
    Disconnect the parking brake switch connector.

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

    Resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    1 - Body ground
    		 Parking brake switch ON
    (Switch pin free)
    		 Below 1 Ω
    1 - Body ground
    		 Parking brake switch OFF
    (Switch pin pushed in)
    		 10 kΩ or higher



NG
REPLACE PARKING BRAKE SWITCH
OK


11. CHECK HARNESS AND CONNECTOR (BETWEEN PARKING BRAKE SWITCH AND SKID CONTROL ECU)

  1. C112027E03
    Disconnect the skid control ECU connector S39 and parking brake switch connector.

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

    Resistance:
    Tester Connection
    		 Specified Condition
    S39-14 (PKB) - P4-1
    		 Below 1 Ω
    S39-14 (PKB)
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE SKID CONTROL ECU


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