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 ECM not only if the vehicle speed is low or high but also if the vehicle is or is not moving. The ECM 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 ESC) control every 30 sec. under detecting condition, if an signal is in the detecting condition for more than 20 sec., ECM 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 | 1. Poor connection 2. Open or short in harness 3. Wheel speed sensor(FR) 4. ABS or ESC control unit 5. ECM | |
Enable Conditions | Case 1 |
•
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 |
•
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 < 32kPa
•
TPS < 1%
•
1800rpm ≤ Engine Speed ≤ 6000rpm
•
Transmission in gear | ||
Threshold value | Case 1 |
•
Vehicle Speed ≤ 10kph | |
Case 2 |
•
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 | ||
Fig.1) Normal data & waveforms of VSS (from ABS,ESC(ESP) ECU) when vehicle speed is 6km/h.
Fig.2) Normal data & waveforms of VSS (from ABS,ESC(ESP) ECU) when vehicle speed is 25km/h.
