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.
If the vehicle speed signal is below the specified minimum value under driving, PCM sets P2159.
Item
Detecting Condition
Possible cause
DTC Strategy
Plausibility check
Poor connection
Short in harness
ESC(ESP) control unit
PCM
Enable Conditions
Fuel Cut On
ECT > 40?
1000 < rpm < 4500
Threshold value
Vehicle speed raw signal < 1km/h
Diagnosis Time
3sec
MIL On Condition
2 Driving Cycles
Fig.1) Normal waveforms of VSS (from ESC(ESP) ECU-5KM/H)