Code No.21, 22, 23, 24: Wheel Speed Sensor (FR, FL, RR, RL) System

caution

If there is any problem in the CAN bus lines, an incorrect diagnosis code may be set. Diagnose the CAN bus lines before the diagnosis codes (Refer to GROUP 54D, CAN bus-line diagnostic flow

<L.H.drive vehicles>

<R.H.drive vehicles>

OPERATION

A toothed rotor generates a voltage signal as it moves across the pickup field of each wheel speed sensor.
The amount of voltage generated at each wheel is determined by the clearance between the rotor teeth and the wheel speed sensor, and by the speed of rotation.
The wheel speed sensors transmit the frequency of the voltage signal to the Active stability and traction control system-electronic control unit (ASTC-ECU).
The ABS hydraulic unit modulates the amount of braking force individually applied to each wheel cylinder.

DIAGNOSIS CODE SET CONDITIONS

Diagnosis codes No. 21, 22, 23, and 24 are set in the following cases.

Although no open circuit is found, no input signal from the wheel speed sensors of one or more wheels is received.
Any abnormality is found with the input signals from the wheel speed sensors.

PROBABLE CAUSES

The most likely causes for these diagnosis codes to set are:

Malfunction of the wheel speed sensor
Damaged wiring harness or connector
Malfunction of the rotor
The gap between the wheel speed sensor and the rotor is excessive.
Wheel bearing malfunction
Malfunction of the ASTC-ECU

DIAGNOSIS

STEP 1. M.U.T.-III CAN bus diagnostics

caution

Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.

(1)Connect M.U.T.-III to the 16-pin diagnosis connector.

(2)Turn the ignition switch to the "ON" position.

(3)Diagnose the CAN bus line.

(4)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is the check result normal?

	Go to Step 3.

	Repair the CAN bus line (Refer to GROUP 54D, CAN bus line Diagnostic flow ). Then go to Step 2.

STEP 2. Check whether the diagnosis code is reset.

caution

Before connecting or disconnecting the M.U.T.-III, turn the ignition switch to the "LOCK" (OFF) position.

(1)Turn the ignition switch to the "ON" position.

(2)Erase the diagnosis code.

(3)Turn the ignition switch to the "LOCK" (OFF) position.

(4)Turn the ignition switch to the "ON" position.

(5)Disconnect the M.U.T.-III.

(6)Drive the vehicle with speed exceeds 15 km/h to recognize wheel signals to the ASTC-ECU.

(7)Check if the diagnosis code is set.

(8)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.21, 22, 23 or 24 set?

	Go to Step 3.

	The procedure is complete.

STEP 3. Check the installation condition of the wheel speed sensors.

Check whether the wheel speed sensor or its mounting bolts are loosened.

Q. Is the check result normal?

	Go to Step 4.

	Reinstall the wheel speed sensor correctly. Then go to Step 12.

STEP 4. Inspect the wheel speed sensor.

Check the wheel speed sensor relevant to the diagnosis code. For the applicable inspection procedure, refer to

When code No.21 is set: Wheel speed sensor (FR)
When code No.22 is set: Wheel speed sensor (FL)
When code No.23 is set: Wheel speed sensor (RR)
When code No.24 is set: Wheel speed sensor (RL)

Q. Is the check result normal?

	Go to Step 5.

	NO <wheel speed sensor (FR)> : Go to Step 7.

	NO <wheel speed sensor (FL)> : Go to Step 8.

	NO <wheel speed sensor (RR)> : Go to Step 9.

	NO <wheel speed sensor (RL)> : Go to Step 10.

STEP 5. Check the wheel bearing for looseness.

note

If the wheel bearing is loose, the gap between the wheel speed sensor and rotor may become excessive. Check the hub assembly, for looseness.

When code No.21 is set: Check the front hub assembly <Refer to GROUP 26, Hub and knuckle assembly inspection (RH) >.
When code No.22 is set: Check the front hub assembly <Refer to GROUP 26, Hub and knuckle assembly inspection (LH) >.
When code No.23 is set: Check the rear hub assembly <Refer to GROUP 27, Rear axle hub assembly inspection (RH) >.
When code No.24 is set: Check the rear hub assembly <Refer to GROUP 27, Rear axle hub assembly inspection (LH) >.

Q. Is the check result normal?

	Go to Step 6.

	NO (front wheel bearing backlash is not within the standard value) : Replace the front hub assembly (Refer to GROUP 26, Hub and knuckle assembly disassembly and reassembly ). Then go to Step 12.

	NO (rear wheel bearing backlash is not within the standard value) : Replace the rear hub assembly (Refer to GROUP 27, knuckle removal and installation ). Then go to Step 12.

STEP 6. Check the rotor.

Check the rotor, for foreign material or deformation.

When code No.21 is set: Check the rotor <FR> (Refer to ).
When code No.22 is set: Check the rotor <FL> (Refer to ).
When code No.23 is set: Check the rotor <RR> (Refer to ).
When code No.24 is set: Check the rotor <RL> (Refer to ).

Q. Is the check result normal?

	Go to Step 11.

	NO (front) : If the rotor is contaminated with foreign material, clean it. If the front hub assembly is deformed, replace it (Refer to GROUP 26, Driveshaft assembly ). Then go to Step 12.

	NO (rear) : If the rotor is contaminated with foreign material, clean it. If the rear hub assembly is deformed, replace it (Refer to GROUP 27, Driveshaft assembly ). Then go to Step 12.

STEP 7. Check ASTC-ECU connector D-233, intermediate connector A-03 (L.H.drive vehicles), intermediate connector D-137 (R.H.drive vehicles) and wheel speed sensor (FR) connector A-36 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

	Go to Step 11.

	Repair or replace the damaged component(s). Then go to Step 12.

STEP 8. Check ASTC-ECU connector D-233, intermediate connector A-03 (L.H.drive vehicles), intermediate connector D-137 (R.H.drive vehicles) and wheel speed sensor (FL) connector A-28 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

	Go to Step 11.

	Repair or replace the damaged component(s). Then go to Step 12.

STEP 9. Check ASTC-ECU connector D-232, intermediate connector D-219, D-231 and wheel speed sensor (RR) connector E-27 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

	Go to Step 11.

	Repair or replace the damaged component(s). Then go to Step 12.

STEP 10. Check ASTC-ECU connector D-232, intermediate connector D-219, D-231 and wheel speed sensor (RL) connector E-19 for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q. Is the check result normal?

	Go to Step 11.

	Repair or replace the damaged component(s). Then go to Step 12.

STEP 11. Check whether the diagnosis code is reset.

Check again if the diagnosis code is set.

(1)Turn the ignition switch to the "ON" position.

(2)Erase the diagnosis code.

(3)Turn the ignition switch to the "LOCK" (OFF) position.

(4)Turn the ignition switch to the "ON" position.

(5)Disconnect the M.U.T.-III.

(6)Drive the vehicle with speed exceeds 15 km/h to recognize wheel signals to the ASTC-ECU.

(7)Check if the diagnosis code is reset.

(8)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.21, 22, 23 or 24 set?

	Replace the ASTC-ECU. Then go to Step 12.

	It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction .

STEP 12. Check whether the diagnosis code is reset.

(1)Turn the ignition switch to the "ON" position.

(2)Erase the diagnosis code.

(3)Turn the ignition switch to the "LOCK" (OFF) position.

(4)Turn the ignition switch to the "ON" position.

(5)Disconnect the M.U.T.-III.

(6)Drive the vehicle with speed exceeds 15 km/h to recognize wheel signals to the ASTC-ECU.

(7)Check if the diagnosis code is set.

(8)Turn the ignition switch to the "LOCK" (OFF) position.

Q. Is code No.21, 22, 23 or 24 set?

	Repeat the troubleshooting from Step 1.

	The procedure is complete.