Lexus IS250 · Service Manual BRAKE

C1249/49

Diagnostic trouble codes

DESCRIPTION

The skid control ECU (housed in the actuator assembly) inputs the stop light switch signal and the condition of brake operation.
The skid control ECU has an open detection circuit, which outputs this DTC when detecting an open in the stop light input line while the stop light switch is OFF.
DTC No.
 DTC Detection Condition
 Trouble Area
C1249/49
  1. When IG1 terminal voltage is 9.5 to 17.2 V, an open circuit of the stop light switch continues for 0.3 seconds or more.
  2. When the brake pedal load sensing switch is ON, the master cylinder pressure is 2 Mpa or more and the deceleration calculated from the vehicle speed is 0.2 G or more, the stop light switch is OFF for 2 seconds or more.
  1. STOP SW fuse
  2. Stop light switch
  3. Stop light switch circuit
  4. Stop light control relay (A/T)
  5. Stop light control relay circuit (A/T)
  6. Brake actuator assembly (Skid control ECU)

WIRING DIAGRAM

C126456E01
C126457E01

INSPECTION PROCEDURE

NOTICE:
When replacing the brake actuator assembly, perform zero point calibration (Click here).


1. INSPECT STOP SW FUSE

  1. C106592E05
    Remove the STOP SW fuse from the main body ECU RH.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    STOP SW (7.5A) fuse
    		 Always
    		 Below 1 Ω



NG
REPLACE STOP SW FUSE
OK


2. CHECK STOP LIGHT OPERATION

  1. Install the STOP SW fuse.

  1. Check that the stop light comes on when the brake pedal is depressed, and goes off when the brake pedal is released.

    OK:
    Condition
    		 Illumination Condition
    Brake pedal depressed
    		 ON
    Brake pedal released
    		 OFF



NG
Go to step 9
OK


3. INSPECT SKID CONTROL ECU (STP1 TERMINAL)

  1. F049362E35
    Disconnect the skid control ECU connector.

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-27 (STP1) - Body ground
    		 Stop light switch ON (Brake pedal depressed)
    		 8 to 14 V
    A14-27 (STP1) - Body ground
    		 Stop light switch OFF (Brake pedal released)
    		 Below 1.5 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (STP1 CIRCUIT)
OK


4. INSPECT SKID CONTROL ECU (IG1 AND GND TERMINAL)

  1. F049362E36
    Turn the engine switch on (IG).

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-46 (IG1) - Body ground
    		 Engine switch on (IG)
    		 10 to 14 V

  1. Turn the engine switch off.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-32 (GND1) - Body ground
    		 Always
    		 Below 1 Ω
    A14-1 (GND2) - Body ground
    		 Always
    		 Below 1 Ω



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


5. READ VALUE OF INTELLIGENT TESTER (STOP LIGHT SWITCH AND BRAKE PEDAL LOAD SENSING SWITCH)

  1. Reconnect the skid control ECU connector.

  1. Connect the intelligent tester to the DLC3.

  1. Start the engine.

  1. Select the Data List mode on the intelligent tester.

    ABS / VSC: 
    Item (Display)
    		 Measurement Item / Range (Display)
    		 Normal Condition
    Stop Lamp SW
    		 Stop light switch / ON or OFF
    		 ON: Brake pedal depressed
    OFF: Brake pedal released
    Brake Pedal Load Sensing SW
    		 Brake pedal load sensing switch / ON or OFF
    		 ON: Brake pedal depressed
    OFF: Brake pedal released

  1. Check that the stop light display observed on the intelligent tester changes when the brake pedal is depressed.

    OK:
    When the brake pedal is depressed, the intelligent tester displays "ON".

  1. Slowly depress the brake pedal, and check when the stop light switch and brake pedal load sensing switch turn ON.

    OK:
    First the stop light switch should turn ON, and then the brake pedal load sensing switch should turn ON.


    Result:
    Condition
    		 Proceed to
    OK
    		 A
    NG (The turning on of the stop light switch is not confirmed)
    		 B
    NG (The brake pedal load sensing switch turns on first)
    		 C



B
REPLACE BRAKE ACTUATOR ASSEMBLY

C
Go to step 7
A


6. RECONFIRM DTC

  1. Clear the DTC (Click here).

  1. Check if the same DTC is recorded (Click here).

    Result:
    Condition
    		 Proceed to
    DTC (C1249/49) is not output
    		 A
    DTC (C1249/49) is output
    		 B

    HINT:
    If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (Click here).



 B
REPLACE BRAKE ACTUATOR ASSEMBLY
A

USE SIMULATION METHOD TO CHECK

7. CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

  1. Check the brake pedal height and stop light switch installation (Click here).

    OK:
    The brake pedal and stop light switch are normal.



 NG
ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH
OK


8. RECONFIRM DTC

  1. Clear the DTC (Click here).

  1. Check if the same DTC is recorded (Click here).

    Result:
    Condition
    		 Proceed to
    DTC (C1249/49) is not output
    		 A
    DTC (C1249/49) is output
    		 B

    HINT:
    If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (Click here).



 B
REPLACE BRAKE PEDAL SUB-ASSEMBLY (BRAKE PEDAL LOAD SENSING SWITCH)
A

USE SIMULATION METHOD TO CHECK

9. INSPECT STOP LIGHT SWITCH (POWER SOURCE TERMINAL)

  1. I042363E09
    Disconnect the stop light switch connector.

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    A22-2 - Body ground
    		 Always
    		 10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)
OK


10. INSPECT STOP LIGHT SWITCH

  1. F049369E01
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    1 - 2
    		 Switch pin free
    		 Below 1 Ω
    1 - 2
    		 Switch pin pushed in
    		 10 kΩ or higher


    Result:
    Result
    		 Proceed to
    OK (for A/T)
    		 A
    OK (for M/T)
    		 B
    NG
    		 C



B
Go to step 15

C
REPLACE STOP LIGHT SWITCH
A


11. INSPECT STOP LIGHT CONTROL RELAY

  1. C126459E01
    Remove the stop light control relay.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    3 - 4
    		 Always
    		 Below 1 Ω



NG
REPLACE STOP LIGHT CONTROL RELAY
OK


12. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ENGINE ROOM NO. 2 RELAY BLOCK)

  1. C114575E01
    Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A22-1 - Stop light control relay terminal 4
    		 Always
    		 Below 1 Ω
    A22-1 - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


13. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - ENGINE ROOM NO. 2 RELAY BLOCK)

  1. C114576E01
    Disconnect the skid control ECU connector.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-27 (STP1) - Stop light control relay terminal 3
    		 Always
    		 Below 1 Ω
    A14-27 (STP1) - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


14. RECONFIRM DTC

  1. Clear the DTC (Click here).

  1. Check if the same DTC is recorded (Click here).

    HINT:
    Reinstall the relay, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.


    Result:
    Condition
    		 Proceed to
    DTC (C1249/49) is not output
    		 A
    DTC (C1249/49) is output
    		 B

    HINT:
    If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (Click here).



 B
REPLACE BRAKE ACTUATOR ASSEMBLY
A

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)

15. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU - STOP LIGHT SWITCH)

  1. F049379E01
    Disconnect the skid control ECU connector.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A14-27 (STP1) - A22-1
    		 Always
    		 Below 1 Ω
    A14-27 (STP1) - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


16. RECONFIRM DTC

  1. Reconnect the skid control ECU connector and the stop light switch connector.

  1. Clear the DTC (Click here).

  1. Check if the same DTC is recorded (Click here).

    Result:
    Condition
    		 Proceed to
    DTC (C1249/49) is not output
    		 A
    DTC (C1249/49) is output
    		 B

    HINT:
    If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (Click here).



 B
REPLACE BRAKE ACTUATOR ASSEMBLY
A

INSPECT LIGHTING SYSTEM (STOP LIGHT CIRCUIT)


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