DTC C1401: Front Speed Sensor RH Malfunction; DTC C1271: Low Output Signal of Front Speed Sensor RH (Test Mode DTC); DTC C1272: Low Output Signal of Front Speed Sensor LH (Test Mode DTC); DTC C1402: Front Speed Sensor LH Malfunction [08/2015 - ]: Procedure

1. Turn the engine switch off.
2. Check the speed sensor installation (Refer to INSTALLATION [08/2015 - ] ).

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK

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

   The installation bolt is tightened properly.

   TEXT IN ILLUSTRATION
   
   

   *1	Front Speed Sensor
   *a	No clearance
   *b	OK
   *c	NG

Result: 

NG 

INSTALL FRONT SPEED SENSOR CORRECTLY 

Result: 

OK 

See step  2

1. Remove the front speed sensor (Refer to REMOVAL [08/2015 - ] ).
2. Check the speed sensor tip.

   OK

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

   NOTE:

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

Result: 

NG 

CLEAN OR REPLACE FRONT SPEED SENSOR 

Result: 

OK 

See step  3

1. Remove the front axle hub subassembly (Refer to REMOVAL [08/2015 - ] ).
2. 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.

Result: 

NG 

CLEAN OR REPLACE FRONT SPEED SENSOR ROTOR 

Result: 

OK 

See step  4

1. Turn the engine switch off.
2. Connect the Techstream to the DLC3.
3. Start the engine.
4. Turn the Techstream on.
5. 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 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 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.

6. 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 (Refer to OPERATION CHECK [08/2015 - 08/2017] Refer to OPERATION CHECK [08/2017 - ] ).

   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).

Result: 

OK 

CHECK FOR INTERMITTENT PROBLEMS 

(Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2015 - 08/2017] Refer to HOW TO PROCEED WITH TROUBLESHOOTING [08/2017 - ] )

Result: 

NG 

See step  5

1. Replace the front speed sensor (Refer to REMOVAL [08/2015 - ] ).

Result: 

NEXT 

See step  6

1. Clear the DTC (Refer to DTC CHECK / CLEAR [08/2015 - 08/2017] Refer to DTC CHECK / CLEAR [08/2017 - ] ).
2. Turn the engine switch off.
3. Start the engine.
4. Drive the vehicle at a speed of 40 km/h (25 mph) or more for at least 60 seconds.
5. Check if the same DTC is output (Refer to DTC CHECK / CLEAR [08/2015 - 08/2017] Refer to DTC CHECK / CLEAR [08/2017 - ] ).
   RESULT
   
   

   Result	Proceed to
   DTC is not output	A
   DTC is output	B

Result: 

A 

END 

Result: 

B 

REPLACE FRONT AXLE WITH ABS ROTOR BEARING ASSEMBLY 

(Refer to DISASSEMBLY [08/2015 - ] )