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Last Modified: 11-27-2007 1.6 C
Service Category: Brake Section: Brake Control/Dynamic Control System
Model Year: 2008 Model: LX570 Doc ID: RM000001DXD00JX
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: DESCRIPTION (2008 LX570)

DTC

C1246/46

Master Cylinder Pressure Sensor Malfunction

DESCRIPTION

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



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.

  • The vehicle speed is more than 7 km/h (4 mph).
  • The PM/C1 or PCTRL terminal voltage exceeds 0.86 V.
  • The master cylinder pressure does not change by more than 0.048 MPa (0.5 kgf/cm2, 7.0 psi).

2. The PM/C1 or PCTRL terminal receives interference at least 7 times within 5 seconds.

3. Both of the following conditions continue for at least 1.2 seconds.

  • The stop light switch is off.
  • The PM/C1 or PCTRL terminal voltage is higher than 0.86 V or below 0.3 V.

4. Both of the following conditions continue for at least 1.2 seconds.

  • The VM/C1 or VCTRL terminal voltage is between 4.4 and 5.6 V.
  • The PM/C1 or PCTRL terminal voltage is not between 0.19 and 4.57 V.
  • Master cylinder pressure sensor
  • Pressure control sensor
  • Stop light switch
  • Harness or connector
  • Master cylinder solenoid

INSPECTION PROCEDURE

NOTICE:

When replacing the master cylinder solenoid, perform zero point calibration BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: CALIBRATION (2008 LX570) .

HINT:

When C1249/49 is output together with C1246/46, inspect and repair the trouble areas indicated by C1249/49 first.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (MASTER CYLINDER SENSOR)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG) and turn the Techstream on.

(c) Enter the following menus: Chassis / ABS/VSC/TRAC / Data List.

ABS/VSC/TRAC

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Master Cylinder Sensor

Master cylinder pressure sensor reading/min.: 0 V, max.: 5 V

When brake pedal is released: 0.3 to 0.9 V

The reading increases when the brake pedal is depressed.

(d) Check that the master cylinder pressure value of the master cylinder pressure sensor displayed on the Techstream changes when depressing the brake pedal.

Result

Result

Proceed to

Master cylinder pressure sensor value does not change.

A

Master cylinder pressure sensor value changes but it is not normal.

B

Master cylinder pressure sensor value changes normally.

C
B

2.

CHECK BRAKE PEDAL AND STOP LIGHT SWITCH INSTALLATION

(a) Check the brake pedal height BRAKE SYSTEM (OTHER): BRAKE PEDAL: ADJUSTMENT (2008 LX570)+ .

(b) Check the stop light switch installation BRAKE SYSTEM (OTHER): BRAKE PEDAL: ADJUSTMENT (2008 LX570)+ .

OK:

The brake pedal and stop light switch are normal.

OK

3.

INSPECT SKID CONTROL ECU (STP TERMINAL)

(a) Disconnect the A24 skid control ECU connector.

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

A24-7 (STP) - Body ground

Stop light switch on (Brake pedal depressed)

8 to 14 V

A24-7 (STP) - Body ground

Stop light switch off (Brake pedal released)

Below 1.5 V
OK

4.

RECONFIRM DTC

(a) Clear the DTC BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: DTC CHECK / CLEAR (2008 LX570) .

(b) Check if the same DTC is output BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: DTC CHECK / CLEAR (2008 LX570) .

HINT:

Reinstall the sensors, connectors, etc. and restore the previous vehicle conditions before rechecking for DTCs.

Result

Result

Proceed to

DTC is output.

A

DTC is not output.

B
A