TCS

C1208

Component Location:

General Description
The wheel speed sensor is the essential component the ABS ECU uses to calculate vehicle speed and to determine whether wheel lock occurs. For example, rear wheel speed signal is used as a reference value, for vehicle speed, in front wheel drive vehicles, and if a difference between front and rear wheel speed occurs, then ABS control is performed. The wheel speed sensor generates sine wave signals, based on magnetic field made by a permanent magnet in the speed sensor, when the tone wheel rotates. The frequency and AC voltage changes in proportion to the wheel speed, and the HECU determines the speed by calculating the frequency of the signal.






DTC Description
The ABS ECU monitors the wheel speed sensor signal continuously. The monitoring method for this sensor is to check the (-) side signal of the sensor circuit when a reference voltage is applied to (+) side of the sensor circuit. This code is set when the sensor air gap is out of specified range or when the ABS control cycle is continued abnormally. The HECU checks for air gap malfunctioning by monitoring the sensor signal at speeds between 2 km/h to 10 km/h. Warning lamp is turned OFF if the detected fault is not more than when the IG KEY is turned to ON again, and wheel speeds are more than 10 km/h.

DTC Detecting Condition:

Specification:

Schematic Diagram:

Signal Waveform:

Monitor Scantool Data
1. Engine "ON".
2. Connect scantool to Data Link Connector (DLC).
3. Start and drive vehicle in gear and maintain vehicle speed at or above 10 km/h (6 mph)
4. Monitor the "WHEEL SPEED (RL)" parameter on the Scantool.

a. Specification : Compare with other parameters related to wheel speed sensor.

If it is the same as other parameters, it is in normal condition.






5. Is parameter displayed within specifications?

YES
a. Fault is intermittent caused by poor connection in wheel speed sensor harness (RL) and/or HECU's connector or was repaired and HECU memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.

NO
a. Go to "Component Inspection" procedure.

Component Inspection
1. Ignition "OFF".
2. Disconnect wheel speed sensor connector.
3. Measure resistance between terminal "1,2" of the wheel speed sensor connector.

a. Specification : Approx. 1.385 kohms ± 110 ohms






4. Is the measured resistance within specifications?

YES
a. 1. Check for improper installation of wheel speed sensor. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.
2. Check for damage of rotor teeth or wheel bearing. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.
3. Measure air gap between wheel speed sensor and rotor. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.

- Specification : Air-gap : 0.2 - 1.3 mm






4. Substitute with a known-good HECU and check for proper operation. If problem is corrected, replace HECU and then go to "Verification of Vehicle Repair" procedure.

NO
a. Substitute with a known-good Wheel speed sensor and check for proper operation. If problem is corrected, replace Wheel speed sensor and then go to "Verification of Vehicle Repair" procedure.

Verification of Vehicle Repair
After a repair, it is essential to verify that the fault has been corrected.
1. Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode
2. Using a Scantool, Clear DTC.
3. Operate the vehicle within DTC Detecting Condition in General Information. (Start and drive vehicle in gear and maintain vehicle speed at or above 10 km/h (6 mph))
4. Are any DTCs present?

YES
a. Go to the applicable troubleshooting procedure.

NO
a. System performing to specification at this time.