Lexus SC300 / Lexus SC400. Manual — part 276

WIRING DIAGRAM

DTC

55

Brake Fluid Level Warning Switch Circuit

CIRCUIT DESCRIPTION

The brake fluid level warning switch sends the appropriate signal to the ECU when the brake fluid level drops.

DTC No.

DTC Detecting Condition

Trouble Area

55

Voltage at ECU terminal LBL is 0Vcontinuously for 10

sec. or more.

Brake fluid level.

Brake fluid level warning switch.

Short in brake fluid level warning switchcircuit.

ECU

Fail safe function:

If trouble occurs in this circuit, the ECU cuts off current to the TRAC solenoid relay

and prohibits TRAC control.

DIAGNOSTIC CHART

DIAGNOSTIC CHART

BR–132

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

OK

NG

OK

NG

OK

NG

INSPECTION PROCEDURE

1

Check brake fluid level.

Check the amount of fluid in the bake reservoir.

C

Check and repair brake fluid leakage and add fluid.

2

Check brake fluid level warning switch.

See page

BE–142

.

Replace brake fluid level warning switch.

3

Check for short in all the harness and components connected to brake fluid level warning light
(See page

IN–33

).

Repair or replace harness or connector.

Check and replace ABS & TRAC ECU.

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

BR–133

DTC

56, 57 Pressure Sensor Circuit

CIRCUIT DESCRIPTION

The pressure sensor detects the TRAC accumulator hydraulic pressure and if it is low, it sends signals to the
ECU to operate the pump. If the pressure is high, it sends signals to the ECU to stop the pump.

DTC No.

DTC Detecting Condition

Trouble Area

56

Pressure sensor terminal PR outputs below 1 V for

about 1 sec. or more.

Open or short in pressure sensor circuit.

57

TRAC (BRAKE) control is executed continuouslymore

than 255 times while pressure sensor ONsignal is not

output.

Pressure sensor

Fail safe function:

If trouble occurs in the pressure sensor circuit, the ECU cuts off current to the TRAC

solenoid relay and prohibits TRAC control.

BR–134

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

WIRING DIAGRAM

DIAGNOSTIC CHART

DIAGNOSTIC CHART

–

BRAKE SYSTEM

ANTI–LOCK BRAKE SYSTEM (ABS)

BR–135