The wheel speed sensor is the essential component taht the PCM uses to calculate vehicle speed. This wheel speed sensor is the active hall-sensor type and good at temperature and noise chariteristic. 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 PCM gets vehicle speed through ABS control unit or ESP control unit.
Checking vehicle speed signal every from wheel speed sensor or ABS control unit 30 sec. under detecting condition, if an signal is in the detecting condition for more than 20 sec., PCM sets P0501. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till cosecutive 2 driving cycle.
Item
Detecting Condition
Possible cause
DTC Strategy
? Detects the lack of vehicle speed signal
? Poor connection
? Open or short in harness
? Wheel speed sensor(FR)
? ABS or ESP control unit
? Vehiclee Speed Sensor
? PCM
Enable Conditions
Case 1(Power)
? Engine Running
? No VSS disabling malfunction present
? No TPS fault present
? No MAP fault present
? 11V< Ignition Voltage< 16V
? Engine Coolant Temperature >60°C (140?)
? MAP >55kPa
? 25% = TPS = 60%
? 1200rpm = Engine Speed = 4000rpm
? Vehicle Speed derived from transmission = 10 kph (6.2 mph)
Case 2(Decel)
? MAP< 32kPa
? TPS< 1%
? 1800rpm = Engine Speed = 6000rpm
? Transmission in gear
Threshold value
? VSS Fault Vehicle Speed = 10kph
? Vehicle Speed< 5kph
? Delta Engine Speed = 100rpm
Diagnosis Time
? Continuous (More than 20 seconds failure for every 30 seconds test )
MIL On Condition
? 2 driving cycles