Lexus IS250 · Service Manual BRAKE

C1246/46

Diagnostic trouble codes

DESCRIPTION

Master cylinder pressure sensor is connected to the skid control ECU in the brake actuator assembly.
DTC C1281/81 can be deleted when the master cylinder pressure sensor sends a master cylinder pressure signal or the Test Mode ends. DTC C1281/81 is output only in the Test Mode.
C106656E03
DTC No.
 DTC Detection Condition
 Trouble Area
C1246/46
 When any of the following is detected:
  1. At a vehicle speed of 4.3 mph (7 km/h) or more, when the PMC terminal voltage is over 0.86 V, it does not change by 0.005 V or more for 30 seconds.
  2. Noise occurs in the PMC terminal 7 times or more within 5 seconds.
  3. When the stop light switch is OFF, the PMC terminal voltage is more than 0.86 V or less than 0.3 V for 5 seconds or more.
  4. With the IG1 terminal voltage between 9.5 and 17.2 V, the VCM terminal voltage is not between 4.4 and 5.6 V for 1.2 seconds or more.
  5. When the VCM terminal voltage between 4.4 and 5.6 V, the PCM terminal voltage is not between 0.14 and 4.85 V for 1.2 seconds or more.
  1. Master cylinder pressure sensor
  2. Master cylinder pressure sensor circuit
  3. Stop light switch circuit
  4. Brake actuator assembly

INSPECTION PROCEDURE

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


1. CHECK STOP LIGHT OPERATION

  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
INSPECT STOP LIGHT CIRCUIT
OK


2. READ VALUE OF INTELLIGENT TESTER (MASTER CYLINDER PRESSURE SENSOR)

  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
    Master Cylinder Sensor
    		 Master cylinder pressure sensor 1 reading / min.: 0 V, max.: 5 V
    		 When brake pedal is released: 0.3 to 0.5 V

  1. Check that the brake fluid pressure value of the master cylinder pressure sensor observed on the intelligent tester changes when the brake pedal is depressed.

    OK:
    When the pedal is depressed, voltage displayed on the intelligent tester increases.



 NG
REPLACE BRAKE ACTUATOR ASSEMBLY
OK


3. READ VALUE OF INTELLIGENT TESTER (STOP LIGHT SWITCH)

  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

  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".



 NG
REPLACE BRAKE ACTUATOR ASSEMBLY
OK


4. RECONFIRM DTC

  1. Turn the engine switch off.

  1. Clear the DTC (Click here).

  1. Start the engine.

  1. At a speed of 18 mph (30 km/h) or more, drive the vehicle and perform braking test (decelerate the vehicle by depressing the brake pedal).

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

    Result:
    Condition
    		 Proceed to
    DTC (C1246/46) is not output
    		 A
    DTC (C1246/46) is output
    		 B



B
REPLACE BRAKE ACTUATOR ASSEMBLY
A

USE SIMULATION METHOD TO CHECK


← C1241/41C1249/49 →