4.
Monitor the "Wheel Speed Sensor" parameter on the Scantool.
Specification : Compare with another parameters related to wheel speed sensor. If it is the same as another parameters, it is in normal condition
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 referecnce 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 chariteristic. 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 calculate vehicle speed by this frequency.
The ABS ECU monitors the wheel speed sensor signal continuously. This code is set when an abnormal signal due to air gap problem or an abnormal speed change ratio are detected at the vehicle speed between 10 km/h to 80 km/h. 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.
Item | Detecting Condition | Possible cause | ||
DTC Strategy | ● Signal monitoring | ● Improper installation of wheel speed sensor ● Abnormal Rotor and wheel bearing ● Inoperative Wheel speed sensor ● Inoperative HECU | ||
Case1 | Monitoring Period | ● The monitoring is active from 10 km/h to 80 km/h and if no ABS-control is active at a front wheel and a rear wheel. | ||
Enable Conditions | ● Every time, if a gap in the wheel speed sensor signal occurs cyclically with one wheel rotation, a fault counter is increased by one. If the fault counter exceeds its limit of 6, a wheel specific fault is stored in the EEPROM. | |||
Case2 | Monitoring Period | ● Continuous | ||
Enable Conditions | ● If following interference and signal disturbance is detected, a failure is set after 10 s. non-plausible high frequency received. non-plausible high wheel acceleration. non-plausible high wheel jurk. non-plausible delta T and edges at low speed. | |||
Fail Safe | ● Sensor failure outside of the ABS control cycle
● Sensor failure inside the ABS control cycle
| |||
Engine "ON".
Connect scantool to Data Link Connector(DLC).
Start and drive vehicle in gear and maintain vehicle speed at or above 12 km/h(7 mph)
Monitor the "Wheel Speed Sensor" parameter on the Scantool.
Specification : Compare with another parameters related to wheel speed sensor. If it is the same as another parameters, it is in normal condition
Is parameter displayed within specifications?
▶ Fault is intermittent caused by faulty HECU or external noise, was repaired and HECU memory was not cleared. 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.
▶ Go to "Component Inspection" Procedure.
Lift the vehicle.
Ignition "ON".
Turn the wheel with hand.
Measure waveform between terminal "1" of the wheel speed sensor harness connector and chassis ground.
Specification : High : 1.05 V , Low : 0.525 V
Is the measured waveform within specifications?
▶ Fault is intermittent caused by poor connection in wheel speed sensor harness or external noise, Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage and external noise, an interference between harnesses. Repair or replace as necessary and then go to "Verification Of Vehicle Repair" procedure.
▶ If OK, 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.
▶ 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.
After a repair, it is essential to verify that the fault has been corrected.
Connect scantool and select "Diagnostic Trouble Codes (DTCs)" mode
Using a scantool, Clear DTC.
Operate the vehicle within DTC Detecting Condition in General Information.(Start and drive vehicle in gear and maintain vehicle speed at or above 12 km/h (7 mph))
Are any DTCs present ?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
