C1202

C1202

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.
Wheel speed sensor is active hall-sensor type and good at temperature and noise characteristic.
Digital waveform is produced as tone wheel rotate according as hall sensor principle.
Frequency of duty waveform is changed in proportion to rotation of tone wheel and HECU calculates vehicle speed by this frequency.






DTC Description
The ABS ECU monitors the wheel speed sensor signal continuously.
This code is set when there is no wheel speed signals within 10 ms to 20 ms at a vehicle speed > 43.2 km/h (26.84 MPH) or a deviation between sensors exceed the threshold or one or two wheels are at 2.75 km/h (1.7 MPH) while the vehicle speed is at 12 km/h (7.4 MPH).
Warning lamp is turned OFF unless additional faults are detected when the IG KEY is turned ON again, and wheel speed is more than 12 Km/h (7.4 MPH).

DTC Detecting Condition Part 1:

DTC Detecting Condition Part 2:

DTC Detecting Condition Part 3:

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 is approx. 50 km/h or more(31 mph or more)
4. Monitor the "WHEEL SPD SENSOR-FL" parameter on the Scantool.

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
- Fault is intermittent caused by poor connection in wheel speed sensor harness (FL), Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
- Repair as necessary and then go to "Verification of vehicle Repair" procedure.

NO - Go to "Component Inspection" Procedure.

Component Inspection
1. Lift the vehicle.
2. Ignition "ON".
3. Turn the wheel by hand.
4. Measure waveform between terminal "1" of the wheel speed sensor harness connector and chassis ground.

Specification: High: 1.05 V, Low: 0.525 V






5. Is the measured waveform within specifications?

YES
- Fault is intermittent caused by poor connection in wheel speed sensor harness.
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.
- 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
- Check for improper installation of wheel speed sensor. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.
- Check for damage of rotor teeth or wheel bearing. If NG, repair as necessary and then go to "Verification of vehicle Repair" procedure.
- 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 is approx. 50 km/h or more (31 mph or more))
4. Are any DTCs present?

YES - Go to the applicable troubleshooting procedure.

NO - System performing to specification at this time.