Toyota Tacoma 2015-2018 Service Manual: Front Speed Sensor RH Malfunction (C1401,C1402)

Toyota Tacoma 2015-2018 Service Manual / Brake Control / Dynamic Control Systems / Vehicle Stability Control System(for Vacuum Brake Booster) / Front Speed Sensor RH Malfunction (C1401,C1402)

DESCRIPTION

The speed sensor detects wheel speed and sends the appropriate signals to the skid control ECU (brake actuator assembly). 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 (brake actuator assembly).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
C1401	Front Speed Sensor RH Malfunction	Any of the following is detected: At a vehicle speed of 10 km/h (6 mph) or more, output voltage from one of the speed sensors is less than that from the other sensors for 15 seconds or more. At a vehicle speed less than 10 km/h (6 mph), output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more. At a vehicle speed of 10 km/h (6 mph) or more, outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more. (except both rear speed sensors are 0 km/h (0 mph))	Front speed sensor RH Front axle with ABS rotor bearing assembly RH Sensor installation
C1402	Front Speed Sensor LH Malfunction	Any of the following is detected: At a vehicle speed of 10 km/h (6 mph) or more, output voltage from one of the speed sensors is less than that from the other sensors for 15 seconds or more. At a vehicle speed less than 10 km/h (6 mph), output from one of the speed sensors is 0 km/h (0 mph) for 1 second or more. At a vehicle speed of 10 km/h (6 mph) or more, outputs from both front speed sensors are 0 km/h (0 mph) for 15 seconds or more. (except both rear speed sensors are 0 km/h (0 mph))	Front speed sensor LH Front axle with ABS rotor bearing assembly LH Sensor installation

HINT:

DTC will be output when conditions for any of the patterns in the table above are met.

PROCEDURE

1.	CHECK FRONT SPEED SENSOR INSTALLATION

(a) Turn the ignition switch off.

(b) Check the speed sensor installation (See page OK: OK: ).

OK:

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

The installation bolt is tightened properly.

Text in Illustration

*a	Normal
*b	Abnormal
*c	Clearance

INSTALL FRONT SPEED SENSOR CORRECTLY

2.	INSPECT FRONT SPEED SENSOR TIP

(a) Remove the front speed sensor (See page (b) Check the speed sensor tip. ).

(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.
If there is iron powder sticking to the rotor, this will result in a malfunction, so confirm that the rotor is not contaminated with foreign material before replacing the sensor.
Check the speed sensor signal after cleaning or replacement (See page ).

Result

Proceed to
OK
NG

CLEAN OR REPLACE FRONT SPEED SENSOR

3.	INSPECT FRONT AXLE WITH ABS ROTOR BEARING ASSEMBLY

(a) Remove the front axle hub inner bearing (See page (b) Check the front skid control rotor. ).

(b) Check the front skid control rotor.

OK:

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

NOTICE:

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

HINT:

The front skid control rotor is incorporated into the front axle hub inner bearing.
If the skid control rotor needs to be replaced, replace it together with the front axle hub inner bearing.

for the front speed sensor: (See page )
for the front axle hub inner bearing: (See page )

CLEAN OR REPLACE FRONT AXLE HUB INNER BEARING

4.	READ VALUE USING TECHSTREAM (FRONT SPEED SENSOR)

(a) Connect the Techstream to the DLC3.

(b) Start the engine.

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

(e) According to the display on the Techstream, read the Data List.

ABS/VSC/TRAC

Tester Display	Measurement Item	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)	Vehicle stopped: 0 km/h (0 mph)	When driving at constant speed: No large fluctuations
FL Wheel Speed	Front wheel speed sensor LH reading/ Min.: 0 km/h (0 mph), Max.: 326 km/h (202 mph)	Vehicle stopped: 0 km/h (0 mph)	When driving at constant speed: No large fluctuations

(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, see the reference chart (See page OK: OK: ).

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).

HINT:

If troubleshooting has been carried out according to the Problem Symptoms Table, refer back to the table and proceed to the next step (See page ).

USE SIMULATION METHOD TO CHECK

5.	REPLACE FRONT SPEED SENSOR

(a) Turn the ignition switch off.

(b) Replace the front speed sensor (See page NOTICE: ).

NOTICE:

After replacing the speed sensor, perform a Test Mode (signal check) inspection sensor check (See page ).

6.	RECONFIRM DTC

(a) Clear the DTCs (See page (b) Turn the ignition switch off. ).

(b) Turn the ignition switch off.

(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 recorded (See page Result Result ).

Result

Result	Proceed to
DTCs C1401 and C1402 are not output	A
DTCs C1401 and/or C1402 are output	B

NOTICE:

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

HINT:

The front skid control rotor is incorporated into the front axle hub inner bearing.
If the front skid control rotor needs to be replaced, replace it together with the front axle hub inner bearing.

END

REPLACE FRONT AXLE HUB INNER BEARING

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