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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: RM000001EA800LX
Title: BRAKE CONTROL / DYNAMIC CONTROL SYSTEMS: VEHICLE STABILITY CONTROL SYSTEM: DESCRIPTION (2008 LX570)

DTC

C1254/54

Pressure Switch Circuit

DESCRIPTION

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



DTC Code

DTC Detection Condition

Trouble Area

C1254/54

There is an accumulator pressure sensor malfunction (the fluid pressure does not change when the pump operates or when the brake is applied).
  • Hydraulic brake booster
  • Accumulator pressure sensor
  • Master cylinder pressure sensor

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) .

PROCEDURE

1.

READ VALUE USING TECHSTREAM (ACCUMULATOR SENSOR)

(a) Turn the engine switch off.

(b) Connect the Techstream to the DLC3.

(c) Depress the brake pedal more than 20 times.

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

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

ABS/VSC/TRAC

Tester Display

Measurement Item/Range

Normal Condition

Diagnostic Note

Accumulator Sensor

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

3.58 to 5 V

If the value is constant regardless of the pump operation, an accumulator pressure sensor malfunction is suspected.

(f) Check the accumulator output value.

Result

Result

Proceed to

Output value is within the "Normal Condition" range.

A

Output value is out of the "Normal Condition" range.

B

Output value is constant regardless of pump operation.
A

2.

READ VALUE USING TECHSTREAM (MASTER CYLINDER SENSOR)

(a) Turn the engine switch off.

(b) Depress the brake pedal more than 20 times.

(c) Install the brake pedal effort gauge (SST), and bleed air.

SST: 09709-29018

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

(e) 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

0.3 to 1.8 V

With pedal effort of 49 N (5 kgf, 11 in.*lbf)

The front brake pressure is 930 to 2130 kPa (9.5 to 21.7 kgf/cm2, 135 to 309 psi).

(f) Check that the master cylinder pressure sensor output value is normal.

OK:

Master cylinder pressure sensor value is normal.

OK

3.

RECONFIRM DTC

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

(b) Turn the engine switch off.

(c) Depress the brake pedal more than 20 times.

(d) Turn the engine switch on (IG).

(e) Wait until the pump motor stops.

(f) Depress the brake pedal and release it.

(g) Wait for 25 minutes.

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

Result

Result

Proceed to

DTC is output.

A

DTC is not output.

B
A