The Vehicle Speed Sensor (VSS) generates a waveform with a frequency according to the speed of the vehicle. The signal generated by VSS informs the ECM not only the vehicle speed is low or high but also the vehicle stops or not. The ECM uses this signal to control fuel injection, ignition timing, transmission/transaxle shift scheduling and torque converter clutch scheduling.
If there is no signal’s change, the ECM judged as a fault and DTC is set.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Output frequency(Fvss) is monitored | ● Poor connection ● Open or short in VSS circuit ● Defective VSS ● Defective ECM |
Enable Conditions | ● Idle switch "OFF" ● Engine speed>2500rpm ● Load value>60% ● After cranking 2sec. | |
Threshold value | ● Output frequency(Fvss) = 0 | |
Diagnostic Time | ● Continuous | |
MIL ON condition | ● 2 driving cycles |