Lexus NX manuals

Lexus NX: Master Cylinder Pressure Sensor (C1246,C1281,C1364)

Lexus NX Service Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System / Master Cylinder Pressure Sensor (C1246,C1281,C1364)

DESCRIPTION

The regulator pressure sensor and wheel cylinder pressure sensor are built into the brake actuator. They measure their respective pressures and send signals to the skid control ECU (brake booster with master cylinder assembly).

DTC C1281 will be cleared when the regulator pressure sensor sends a regulator pressure signal or when Test Mode ends. DTC C1281 is output only in Test Mode.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

Note

C1246

Master Cylinder Pressure Sensor

201

202

203

204

207
  • INF Code: 201
    • Sensor supply voltage (VCM1) is 4.75 V or less, or 5.25 V or more for 0.05 seconds.
  • INF Code: 202
    • Regulator pressure sensor output voltage (Preg) is less than 8%, or 90.3% or more (less than 0.4 V, or 4.52 V or more) of sensor supply voltage (VCM1) for 0.05 seconds or more.
  • INF Code: 203
    • When not under braking, the regulator pressure sensor output voltage is 0.2 V or less or 0.88 V or more for 3 seconds or more.
  • INF Code: 204
    • Either of the following is detected:
      1. The regulator pressure sensor output voltage does not correspond with brake pedal stroke sensor assembly and the readings remain out of specification for 0.5 to 5 seconds or more continuously.

        (The brake pedal stroke sensor assembly may be malfunctioning.)

      2. The regulator pressure sensor output voltage does not correspond with wheel cylinder pressure sensor and the outputs remain out of specification for 0.5 to 5 seconds or more continuously.

        (May be output with INF code 424.)

  • INF Code: 207
    • Fluctuation of regulator pressure sensor output is out of specification (the difference between the present value and last value is 15 MPa (153.0 kgf/cm2, 2176 psi) or more) for 0.1 seconds or more.
  • INF Code: 201, 202, 203, 207
    • Brake booster with master cylinder assembly
  • INF Code: 204
    • Brake pedal stroke sensor assembly
    • Brake booster with master cylinder assembly

-

C1281

Abnormal Output in Master Cylinder Pressure Sensor

-

Detected only during Test Mode.
  • Stop light switch assembly
  • Regulator pressure sensor (Brake booster with master cylinder assembly)

-

C1364

Wheel Cylinder Pressure Sensor

421

422

423

424

426
  • INF Code: 421
    • Sensor supply voltage 1 (VCM1) is 4.75 V or less, or 5.25 V or more for 0.05 seconds or more.
  • INF Code: 422
    • Wheel cylinder pressure sensor output voltage (Pfront) is less than 8%, or 90.3% or more (less than 0.4 V, or 4.52 V or more) of sensor supply voltage (VCM1) for 0.05 seconds or more.
  • INF Code: 423
    • When not under braking, the wheel cylinder pressure sensor output voltage is 0.2 V or less or 0.88 V or more for 0.1 to 3 seconds or more.
  • INF Code: 424
    • The wheel cylinder pressure sensor output voltage does not correspond with regulator pressure sensor and the outputs remain out of specification for 0.5 to 5 seconds or more continuously.

      (May be output with INF code 204.)

  • INF Code: 426
    • Fluctuation of wheel cylinder pressure sensor output is out of specification (the difference between the present value and last value is 15 MPa (153.0 kgf/cm2, 2176 psi) or more) for 0.1 seconds or more.

Brake booster with master cylinder assembly

-

CAUTION / NOTICE / HINT

NOTICE:

When replacing the skid control ECU (brake booster with master cylinder assembly) or brake actuator (brake booster with master cylinder assembly), perform initialization and calibration of the linear solenoid valve.

Click here

PROCEDURE

1.

CHECK STOP LIGHT SWITCH ASSEMBLY INSTALLATION

(a) Check the protrusion of the plunger.

Click here

OK:

The stop light switch assembly is installed properly.

HINT:

If the stop light switch assembly is not installed properly, adjust the protrusion of the plunger before proceeding to the next step.

NG

ADJUST PROTRUSION OF SHAFT

OK

2.

READ VALUE USING TECHSTREAM (REGULATOR PRESSURE SENSOR)

(a) Mount a pedal effort gauge and install LSPV gauges to the rear wheels.

Click here

(b) Connect the Techstream to the DLC3.

(c) Turn the power switch on (IG).

(d) Select the Data List on the Techstream.

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Regulator Pressure Sensor Output

Regulator pressure sensor output

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 0.10 to 0.90 V

Reading increases when brake pedal is depressed
Chassis > ABS/VSC/TRAC > Data List

Tester Display

Regulator Pressure Sensor Output

(e) Check the output value of the regulator pressure sensor as the brake pedal is depressed.

Standard Voltage:

Brake Effort

(N (kgf, lbf))

Regulator Pressure Sensor Output

(V)

Rear Right Wheel Hydraulic Pressure

(MPa (kgf/cm2, psi))

Rear Left Wheel Hydraulic Pressure

(MPa (kgf/cm2, psi))

100 (10, 22.5)

1.51 to 2.31

4.89 to 8.89 (49.9 to 90.6, 709 to 1289)

4.89 to 8.89 (49.9 to 90.6, 709 to 1289)

200 (20, 45.0)

3.17 to 3.97

13.06 to 17.06 (133.2 to 173.9, 1894 to 2473)

13.06 to 17.06 (133.2 to 173.9, 1894 to 2473)
NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

OK

3.

READ VALUE USING TECHSTREAM (WHEEL CYLINDER PRESSURE SENSOR)

(a) Install LSPV gauges to the front wheels.

Click here

(b) Select the Data List on the Techstream.

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Wheel Cylinder Pressure Sensor

Wheel cylinder pressure sensor

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 0.10 to 0.90 V

Reading increases when brake pedal is depressed
Chassis > ABS/VSC/TRAC > Data List

Tester Display

Wheel Cylinder Pressure Sensor

(c) Check the output values of the wheel cylinder pressure sensor at each hydraulic pressure during electronically controlled brake system control.

Standard Voltage:

for Front Wheel Cylinder LH

Hydraulic Pressure

(MPa (kgf/cm2, psi))

Wheel Cylinder Pressure Sensor

(V)

2.0 (20.4, 290)

0.53 to 1.33

5.0 (51.0, 725)

1.12 to 1.92

7.0 (71.4, 1015)

1.52 to 2.32

10.0 (102.0, 1451)

2.14 to 2.94
for Front Wheel Cylinder RH

Hydraulic Pressure

(MPa (kgf/cm2, psi))

Wheel Cylinder Pressure Sensor

(V)

2.0 (20.4, 290)

0.53 to 1.33

5.0 (51.0, 725)

1.12 to 1.92

7.0 (71.4, 1015)

1.52 to 2.32

10.0 (102.0, 1451)

2.14 to 2.94
NG

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

OK

4.

READ VALUE USING TECHSTREAM (BRAKE PEDAL STROKE SENSOR ASSEMBLY AND PRESSURE SENSOR COMPARISON)

(a) Mount a pedal effort gauge and install LSPV gauges to the front and rear wheels.

Click here

(b) Select the Data List on the Techstream.

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Regulator Pressure Sensor Output

Regulator pressure sensor output

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 0.10 to 0.90 V

Reading increases when brake pedal is depressed

Stroke Sensor

Brake pedal stroke sensor assembly

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 0.65 to 1.35 V

Reading increases when brake pedal is depressed

Stroke Sensor2

Brake pedal stroke sensor assembly 2

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 3.65 to 4.35 V

Reading decreases when brake pedal is depressed

Wheel Cylinder Pressure Sensor

Wheel cylinder pressure sensor

Min.: 0.00 V, Max.: 5.00 V

Brake pedal released: 0.10 to 0.90 V

Reading increases when brake pedal is depressed
Chassis > ABS/VSC/TRAC > Data List

Tester Display

Regulator Pressure Sensor Output

Stroke Sensor

Stroke Sensor2

Wheel Cylinder Pressure Sensor

(c) Check the output value of the brake pedal stroke sensor assembly as the brake pedal is depressed.

Standard Voltage:

Brake Effort

(N (kgf, lbf))

Stroke Sensor

(V)

Stroke Sensor2

(V)

Regulator Pressure Sensor Output

(V)

Wheel Cylinder Pressure Sensor

(V)

100 (10, 22.5)

1.56 to 2.26

2.74 to 3.44

1.51 to 2.31

1.30 to 2.10

200 (20, 45.0)

2.11 to 2.81

2.19 to 2.89

3.17 to 3.97

2.73 to 3.53
NG

REPLACE BRAKE PEDAL STROKE SENSOR ASSEMBLY

OK

5.

RECONFIRM DTC

(a) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

(b) Turn the power switch off.

(c) Perform a road test.

(d) Check if the same DTC is output.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result

Proceed to

DTCs C1246 and C1364 are not output.

A

DTCs C1246 and/or C1364 are output.

B
A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY

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