The Wheel Speed Sensor (WSS) generates a waveform with a frequency proportional to the speed of the vehicle. The signal generated by the WSS informs the PCM not only if the vehicle speed is low or high but also if the vehicle is or is not moving. The PCM uses this signal to control the fuel injection, ignition timing, transaxle shift scheduling and torque converter clutch scheduling. The WSS signal is also used to detect rough road conditions.
Checking vehicle speed signal every from ABS(or ESP) control every 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 consecutive 2 driving cycle.
Item
Detecting Condition
Possible cause
DTC Strategy
? Detects the lack of vehicle speed signal to the PCM
? Poor connection
? Open or short in harness
? Wheel speed sensor(FR)
? ABS or ESP control unit
? 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?(140?)
? MAP > 55kPa
? 25% = TPS = 60%
? 1200rpm = Engine Speed = 4000rpm
? Vehicle Speed derived from transmission = 10KPH(6.2MPH)
Case 2(Decel)
? MAP < 32kPa
? TPS < 1%
? 1800rpm = Engine Speed = 6000rpm
? Transmission in gear
Threshold value
? 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