Code No.15: Wheel
Speed Sensor (output signal error)
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 ABS-ECU.
- The ABS hydraulic unit modulates the amount of braking force individually applied
to each wheel cylinder.
DIAGNOSIS CODE SET CONDITION
When the vehicle speed is 20 km/h or more and one or more input values of the
four wheel speed sensors differ from other wheel speeds
PROBABLE CAUSES
- Incorrect tyre size
- Wear or deformation of tyre
- Improperly installed wheel speed sensor
- Malfunction of the wheel speed sensor
- Damaged wiring harness or connector
- Malfunction of the rotor
- Wheel bearing malfunction
- Malfunction of the ABS-ECU
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STEP 1. Check the tyre size.
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Carry out the following check.
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- Check if the tyres of 4 wheels are uniform and adequate in size.
- Is there any tyre which is abnormally worn or deformed?
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Q.
Is the check result normal?
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 Go to Step 2.
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 Replace the tyre.
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STEP 2. Inspect the wheel speed sensor.
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Check the mounting bolt of wheel speed sensor for looseness.
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Q.
Is the check result normal?
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Go to Step 3.
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Install the wheel speed sensor(s) properly.
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STEP 3. Inspect the wheel speed sensor output voltage.
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Refer to  .
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Q.
Is the check result normal?
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Go to Step 6.
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Go to Step 4.
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STEP 4. Inspect the wheel speed sensor and rotor.
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Check the following items. For inspection service points, refer to .
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- Resistance between wheel speed sensor terminals
- Wheel speed sensor insulation resistance
- Rotor tooth check
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Q.
Is the check result normal?
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Go to Step 5.
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Replace the wheel speed sensor or the rotor.
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STEP 5. Check the wheel bearing for looseness.
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- Front: Refer to GROUP 26, Hub and knuckle assembly inspection .
- Rear: Refer to GROUP 27, Rear axle hub assembly inspection .
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Q.
Is the check result normal?
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Go to Step 6.
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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 ).
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NO (rear wheel bearing backlash is not within the standard value) : Replace the rear hub assembly (Refer to GROUP 27, Rear axle hub and knuckle assembly disassembly
and reassembly ).
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STEP 6. Check whether the diagnosis code is reset.
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Check again if the diagnosis code is set.
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(1)Drive the vehicle with speed exceeds 8 km/h to recognize wheel signals
to the ABS-ECU.
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(2)Erase the diagnosis code.
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(3)Turn the ignition switch to the "LOCK" (OFF) position.
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(4)Turn the ignition switch to the "ON" position.
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(5)Disconnect the M.U.T.-III.
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(6)Drive the vehicle with speed exceeds 20 km/h to recognize wheel signals
to the ABS-ECU.
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(7)Check if the diagnosis code is reset.
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(8)Turn the ignition switch to the "LOCK" (OFF) position.
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Replace the ABS-ECU. Then go to Step 7.
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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 .
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STEP 7. Check whether the diagnosis code is reset.
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Check again if the diagnosis code is set.
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(1)Drive the vehicle with speed exceeds 8 km/h to recognize wheel signals
to the ABS-ECU.
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(2)Erase the diagnosis code.
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(3)Turn the ignition switch to the "LOCK" (OFF) position.
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(4)Turn the ignition switch to the "ON" position.
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(5)Disconnect the M.U.T.-III.
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(6)Drive the vehicle with speed exceeds 20 km/h to recognize wheel signals
to the ABS-ECU.
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(7)Check if the diagnosis code is reset.
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(8)Turn the ignition switch to the "LOCK" (OFF) position.
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Repeat the troubleshooting from Step 1.
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The procedure is complete.
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