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, if the speed difference with adjacent wheel is out of permissible range or the ABS control cycle is abnormal.
Item | Detecting Condition | Possible cause | |
Case 1 | DTC Strategy | ● Signal motorning | ● Improper installation of wheel speed sensor ● Abnormal Rotor and wheel bearing ● Inoperative Wheel speed sensor ● Inoperative HECU |
Monitoring Period | ● Continous | ||
Enable Conditions | ● When short cut between the wheel speed sensor supply and the battery. | ||
Fail Safe | ● Wheel speed sensor signals are not reliable. | ||
Case 2 | DTC Strategy | ● Signal motorning | |
Monitoring Period | ● Continous | ||
Enable Conditions | ● The monitoring reports a failure if the ABS target slip is exceeded for a time period ＞= 10 s at one or more wheels. - If the driver brakes or the velocity is lower than 50 km/h the detection time is enlarged to 60 s. | ||
Fail Safe | ● Reduced function of the ESP system | ||
Engine "ON".
Connect scantool to Data Link Connector(DLC).
Start and drive vehicle in gear and maintain vehicle speed at or above 10 km/h(6 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 poor connection in wheel speed sensor harness, 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 "1,2" of the wheel speed sensor harness connector and chassis ground.
Specification :
High : 1.05 V , Low : 0.525 V
Compare waveforms of all wheel speed sensors.
If they have same waveform, it is in normal condition.
Is the measured waveform within specifications?
▶ 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.
▶ Check following point at wheel speed sensor which has abnormal waveform.
▶ 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 is approx. 50km/h or more(31mph or more))
Are any DTCs present ?
▶ Go to the applicable troubleshooting procedure.
▶ System performing to specification at this time.
