One sensor at each wheel hub - front sensors mount to steering knuckle, rear sensors mount to axle housing or backing plate facing tone ring on axle shaft or hub bearing
Pins
2-pin connector
0
Timebase
10ms/div at 30mph, 5ms/div at 60mph
Voltage Scale
500mV/div to 1V/div
Trigger
0V, rising or falling edge
Wiring
Varies by wheel position - typically twisted pair, front left: White/Yellow and Light Blue, front right: Brown/White and Orange/Black, rear sensors similar color combinations, all are differential signal pairs
Expected Voltage Range
At Idle
0V to 0V
At Higher RPM
-2.5V to 2.5V
Expected Pattern
AC sine wave with frequency proportional to wheel speed, amplitude increases with speed, 60 pulses per revolution from 60-tooth tone ring
Known-Good Waveform
At 30mph, expect clean sine wave at approximately 35-40Hz with amplitude of 0.8-2.0V peak-to-peak. Amplitude increases with speed - at 60mph expect 1.5-3.5V peak-to-peak at 70-80Hz. All four sensors should show similar waveforms at same vehicle speed. Zero crossing should be clean with no distortion and consistent frequency.
Common Failure Patterns
No signal output or intermittent dropout during rotation
Cause: Broken sensor wire, corroded connector, or damaged sensor coil
Compare all four wheel speed sensors simultaneously during a road test - they should show identical frequency at same speed and similar amplitude. Ford F-150 4WD models commonly experience rear sensor damage from road debris. Check for metallic debris on sensor tip and verify air gap with feeler gauge. Worn wheel bearings are a common cause of erratic WSS signals on higher mileage trucks.
Related Diagnostic Trouble Codes
C0035C0040C0045C0050
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.