Last Modified: 4-30-2014 6.6 C Doc ID: RM000001A6C002X
Model Year: 2006 Model: LX470 Prod Date Range: [05/2005 -           ]
Title: BRAKE CONTROL: VEHICLE STABILITY CONTROL SYSTEM: C1246/46; Master Cylinder Pressure Sensor Malfunction; 2006 MY LX470 [05/2005 -        ]

DTC

C1246/46

Master Cylinder Pressure Sensor Malfunction

DESCRIPTION

DTC No.

DTC Detection Condition

Trouble Area

C1246/46

One of the following 1., 2., 3., 4. or 5. is detected:

  1. At a vehicle speed of 7 km/h (4 mph) or more, PMC terminal voltage does not change by more than 0.005 V once it exceeds 0.86 V continues for at least 30 seconds.
  2. Interference occurs to ECU terminal PMC 7 times or more for 5 sec.
  3. ECU terminal STP is OFF, and the condition that terminal PMC voltage becomes more than 0.86 V or less than 0.3 V continues for 5 sec. or more.
  4. The condition that ECU terminal IG1 voltage is 9.5 V to 17.0 V and terminal VCM voltage other than the range from 4.4 V to 5.6 V continues for 1.2 sec. or more.
  5. The condition that ECU terminal VCN voltage is 4.4 V to 5.6 V, and terminal PMC voltage other than the range from 0.14 V to 4.85 V continues for 1.2 sec. or more.
  • Master cylinder pressure sensor
  • Master cylinder pressure sensor circuit

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

When using the intelligent tester, start from *1. When not using the intelligent tester, start from *2.

PROCEDURE

1.

READ VALUE USING INTELLIGENT TESTER (OIL PRESSURE SENSOR)

(a) Check the DATA LIST for proper functioning of the master cylinder pressure sensor (oil pressure sensor).

Skid control ECU assembly

Item

Measurement Item / Range (Display)

Normal Condition

Diagnostic Note

MAS CYL PRS 1

Master cylinder pressure 1 /

Min.: 0 V, Max.: 5 V

When brake pedal is released: 0.3 to 0.9 V

Reading increases when brake pedal is depressed

OK:

Brake fluid pressure value must be changing.

OK

GO TO STEP 4

NG

2.

CHECK MASTER CYLINDER PRESSURE SENSOR (OIL PRESSURE SENSOR)

(a) Install SST (LSPV gauge) to the front caliper bleeder plug portion, and bleed LSPV gauge.

SST: 09709-29018

(b) Remove the master cylinder cover.

(c) Start the engine and depress the brake pedal, and then check the relation between the fluid pressure and voltage of terminals 22 (PMC) and 12 (E2) of the oil pressure sensor with the connector still connected.

Standard voltage:

Front Brake Caliper Fluid Pressure

Voltage

0 kPa (0 kgf/cm 2 , 0 psi)

0.37 to 0.63 V

5,883 kPa (60 kgf/cm 2 , 853 psi)

1.57 to 1.83 V

11,768 kPa (120 kgf/cm 2 , 1,706 psi)

2.77 to 3.03 V

HINT:

Voltage between terminals 10 (VCM) and 12 (E2) is 4.7 to 5.3 V.
NG

REPLACE MASTER CYLINDER PRESSURE SENSOR

OK

3.

CHECK WIRE HARNESS (SKID CONTROL ECU ASSEMBLY - MASTER CYLINDER PRESSURE SENSOR)
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

REPLACE SKID CONTROL ECU ASSEMBLY

4.

CHECK WHETHER OR NOT THE ECU TERMINAL STP INPUT VOLTAGE IS CHANGED WHEN THE STOP LIGHT SWITCH IS TURNED ON AND OFF
NO

CHECK STOP LIGHT SWITCH CIRCUIT

YES

REPLACE SKID CONTROL ECU ASSEMBLY