Diagnostic trouble code C1246 Land Cruiser

DESCRIPTION

INSPECTION PROCEDURE

CHECK DTC

READ VALUE USING INTELLIGENT TESTER (MASTER CYLINDER SENSOR)

CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE TERMINAL)

INSPECT STOP LIGHT SWITCH ASSEMBLY

RECONFIRM DTC

DTC C1246/46 Master Cylinder Pressure Sensor Malfunction

Description

The master cylinder pressure sensor is connected to the skid control ECU in the master cylinder solenoid.

Diagnostic trouble code C1246 Land Cruiser. Description
DTC Code DTC Detection Condition Trouble Area
C1246/46 When any of the following conditions is detected: 1. All of the following conditions continue for at least 30 seconds.
  1. The vehicle speed is more than 7 km/h (4 mph).
  2. The PM/C1 terminal voltage exceeds 0.86 V.
  3. The master cylinder pressure does not change by more than 0.048 MPa (0.5 kgf/cm2, 7.0 psi).
2. The PM/C1 terminal receives interference at least 7 times within 5 seconds. 3. Both of the following conditions continue for at least 1.2 seconds.
  1. The stop light switch is off.
  2. The PM/C1 terminal voltage is higher than 0.86 V or below 0.3 V.
4. The following condition continues for at least 1.2 seconds.
  1. The PM/C1 terminal voltage is not between 0.19 and 4.57 V.
  1. STOP fuse
  2. Master cylinder pressure sensor
  3. Stop light switch
  4. Harness or connector
  5. Master cylinder solenoid

Inspection procedure

NOTICE:

  1. Inspect the fuses for circuits related to this system before performing the following inspection procedure.
  2. When replacing the master cylinder solenoid, perform zero point calibration .

1.CHECK DTC

  1. Clear the DTC .

  1. Turn the ignition switch off.

  1. Start the engine.

  1. Depress the brake pedal.

  1. Check for DTC .

    Result
    Result Proceed to
    DTC C1246/46 is output A
    DTCs C1246/46 and C1249/49 are output B
  B  
GO TO DTC C1249/49
 
A  
   

2.READ VALUE USING INTELLIGENT TESTER (MASTER CYLINDER SENSOR)

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch to ON and turn the intelligent tester on.

  1. Enter the following menus: Chassis / ABS/VSC/TRC / Data List.

    ABS/VSC/TRC
    Tester Display Measurement Item/Range Normal Condition Diagnostic Note
    Master Cylinder Sensor Master cylinder pressure sensor reading / min.: 0.00 V, max.: 5.00 V When brake pedal is released: 0.3 to 0.9 V The reading increases when the brake pedal is depressed.

  1. Check that the master cylinder pressure value of the master cylinder pressure sensor displayed on the intelligent tester changes when depressing the brake pedal.

    Result
    Result Proceed to
    Master cylinder pressure sensor value does not change LHD A
    RHD B
    Master cylinder pressure sensor value changes but it is not normal C
    Master cylinder pressure sensor value changes normally
  B  
REPLACE MASTER CYLINDER SOLENOID
 
  C  
Go to step 3
 
A  
   
REPLACE MASTER CYLINDER SOLENOID

3.CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

  1. Check the brake pedal height (LHD:).

  1. Check the stop light switch installation (LHD:/RHD:).

    OK:

    The brake pedal and stop light switch are normal.

    Result
    Result Proceed to
    OK A
    NG LHD B
    RHD C
  B  
ADJUST BRAKE PEDAL AND/OR STOP LIGHT SWITCH
 
  C  
ADJUST BRAKE PEDAL AND/OR STOP LIGHT SWITCH
 
A  
   

4.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE TERMINAL)

Diagnostic trouble code C1246 Land Cruiser. Disconnect the A30 stop light switch connector.

  1. Disconnect the A30 stop light switch connector.

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

    Standard Voltage:

    Tester Connection Condition Specified Condition
    A30-2 - Body ground Always 11 to 14 V
  NG  
REPAIR OR REPLACE HARNESS OR CONNECTOR
 
OK  
   

5.INSPECT STOP LIGHT SWITCH ASSEMBLY

  1. Remove the stop light switch assembly.

Diagnostic trouble code C1246 Land Cruiser. Measure the resistance according to the value(s) in the table below.

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

    Standard Resistance:

    Tester Connection Switch Condition Specified Condition
    1 - 2 Switch pin free Below 1 ?
    Switch pin pushed in 10 k? or higher
  NG  
REPLACE STOP LIGHT SWITCH ASSEMBLY
 
OK  
   

6.RECONFIRM DTC

  1. Clear the DTC .

  1. Check if the same DTC is output .

    Result
    Result Proceed to
    DTC is not output A
    DTC is output LHD B
    RHD C
  B  
REPLACE MASTER CYLINDER SOLENOID
 
  C  
REPLACE MASTER CYLINDER SOLENOID
 
A  
   
USE SIMULATION METHOD TO CHECK