The wheel speed sensor is the essential component that the ECM uses to calculate vehicle speed. This wheel speed sensor is the active hall-sensor type and good at temperature and noise characteristic. Digital wave is produced as tone wheel rotate according as hall sensor principle. Frequency of duty wave is changed in proportion to rotation of tone wheel and ECM gets vehicle speed through ABS/ESP control unit or the wheel speed sensor(In case of non-ABS/ESP vehicle).
The ECM evaluates engine speed and mass air flow if there is no vehicle speed signal. This evaluation of both value will detect open circuit or short circuit error on wheel speed sensor. The ECM sets DTC P0501 if there is no vehicle speed signal from wheel speed sensor while both engine speed and mass air flow are higher than predetermined threshold during predetermined time.
If the same error code is set in the next driving cycle, the ECM illuminates the MIL.
Item
Detecting Condition
Possible Cause
DTC Strategy
Signal check (implausible)
[ABS/ESP Vehicle]
Poor connection
Open or short in signal circuit
ABS/ESP Module
Faulty ECM
[Non-ABS/ESP Vehicle]
Open or short in power circuit
WSS
Case1
Enable
Conditions
Relative charge of cylinder > 49.5 %
Engine speed > 3000 rpm
Coolant temperature > -6?
Gear position : D or R
Threshold Value
Vehicle speed < 1.0 km/h
Case2
1520 rpm < Engine speed < 4000 rpm
Fuel cut - off
Signal interruption : Vehicle speed < 1.0 km/h
Diagnostic Time
2 sec
MIL ON Condition
3 driving cycle
Fig 1) Vehicle Speed fromWheel Speed S. (Idle)
Fig 2) Vehicle Speed fromWheel Speed S. (Low Speed)
Fig 3) Vehicle Speedfrom ABSM To ECM (Idle)
Fig 4) Vehicle Speedfrom ABSM To ECM (Low Speed)
Fig 5) Vehicle Speedfrom ABSM To ECM (High Speed)