Toyota 4Runner manuals

Toyota 4Runner: Front Speed Sensor RH Malfunction (C1401,C1271,C1272,C1402)

Toyota 4Runner Service Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Hydraulic Brake Booster) / Front Speed Sensor RH Malfunction (C1401,C1271,C1272,C1402)

DESCRIPTION

The speed sensor detects the wheel speed and sends the appropriate signals to the skid control ECU. These signals are used for brake control.

The speed sensor rotors have rows of alternating N and S magnetic poles and their magnetic fields change when the rotors turn.

Each speed sensor detects that magnetic change and sends a pulse signal to the skid control ECU.


DTC Code

DTC Detection Condition

Trouble Area

C1401

C1402

One of the following conditions is met:

  1. At a vehicle speed of 10 km/h (6 mph) or more, the output voltage from one of the speed sensors is less than that from the other sensors for 15 seconds or more.
  2. At a vehicle speed of less than 10 km/h (6 mph), the output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more.
  3. At a vehicle speed of 10 km/h (6 mph) or more, the outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more.
  • Front speed sensor RH/LH
  • Speed sensor rotor
  • Sensor installation

C1271

C1272

Stored only during test mode.
  • Front speed sensor RH/LH
  • Speed sensor rotor
  • Sensor installation

HINT:

  • DTCs C1401 and C1271 are for the front speed sensor RH.
  • DTCs C1402 and C1272 are for the front speed sensor LH.

CAUTION / NOTICE / HINT

NOTICE:

Check the speed sensor signal after cleaning or replacement (See page ).


PROCEDURE

1.

CHECK FRONT SPEED SENSOR INSTALLATION

(a) Turn the ignition switch off.

(b) Check the speed sensor installation.

OK:

There is no clearance between the sensor and the front steering knuckle.

The installation bolt is tightened properly.

Torque

8.5 N*m (87 kgf*cm, 75 in.*lbf)

Text in Illustration

*1

Front Speed Sensor

*a

No clearance

*b

OK

*c

NG


NG

INSTALL FRONT SPEED SENSOR CORRECTLY
OK

2.

INSPECT FRONT SPEED SENSOR TIP

(a) Remove the front speed sensor (See page
).

(b) Check the speed sensor tip.

OK:

No scratches, oil, or foreign matter on the sensor tip.

NOTICE:

If no damage to the speed sensor tip is found during this inspection, do not replace the speed sensor.


NG

CLEAN OR REPLACE FRONT SPEED SENSOR
OK

3.

INSPECT FRONT SPEED SENSOR ROTOR

(a) Remove the front axle with ABS rotor bearing assembly (for 2WD: See page , for 4WD: See page
).


(b) Check the speed sensor rotor.

OK:

No scratches, oil, or foreign matter on the rotors.

HINT:

The front speed sensor rotor is incorporated into the front axle with ABS rotor bearing assembly.

If the front speed sensor rotor needs to be replaced, replace it together with the front axle with ABS rotor bearing assembly.


NG

CLEAN OR REPLACE FRONT SPEED SENSOR ROTOR
OK

4.

READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Start the engine.

(d) 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

FR Wheel Speed

Front wheel speed sensor RH reading/ Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

Actual wheel speed

No large fluctuations when driving at a constant speed.

FL Wheel Speed

Front wheel speed sensor LH reading/ Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)

Actual wheel speed

No large fluctuations when driving at a constant speed.

(f) Check that there is no difference between the speed value output from the speed sensor displayed on the Techstream and the speed value displayed on the speedometer when driving the vehicle.

HINT:

Factors that affect the indicated vehicle speed include tire size, tire inflation and tire wear. The speed indicated on the speedometer has an allowable margin of error. This can be tested using a speedometer tester (calibrated chassis dynamometer). For details about testing and the margin of error, refer to the reference chart (See page ).


OK:

The speed value output from the speed sensor displayed on the Techstream is the same as the actual vehicle speed measured using a speedometer tester (calibrated chassis dynamometer).


OK

USE SIMULATION METHOD TO CHECK

NG

5.

REPLACE FRONT SPEED SENSOR

(a) Replace the front speed sensor (See page
).

NEXT

6.

RECONFIRM DTC

(a) Clear the DTCs (See page ).


(b) Turn the ignition switch off.

(c) Start the engine.

(d) Drive the vehicle at a speed of 40 km/h (25 mph) or more for at least 60 seconds.

(e) Check if the same DTC is output (See page
).

Result

Result

Proceed to

DTCs C1401 and C1402 are not output

A

DTCs C1401 and/or C1402 are output (for 2WD)

B

DTCs C1401 and/or C1402 are output (for 4WD)

C

A

END

B

REPLACE FRONT AXLE WITH ABS ROTOR BEARING ASSEMBLY


C

REPLACE FRONT AXLE WITH ABS ROTOR BEARING ASSEMBLY

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