Vehicle Speed Sensor
2024 Ford F-150 · 3.5L V6 EcoBoost
Sensor Type
hall-effect
Waveform Type
pulse-width
Location
Electronic signal derived from ABS wheel speed sensors and processed by ABS module, no dedicated VSS - signal sent via CAN bus to PCM and instrument cluster
Pins
Unknown
Timebase
500μs/div for CAN bus analysis
Voltage Scale
1V/div
Trigger
2.5V on CAN High line
Wiring
Not applicable - digital CAN bus communication (twisted pair High Speed CAN)
Expected Voltage Range
At Idle
0V to 0V
At Higher RPM
2.5V to 3.5V
Expected Pattern
CAN bus differential signal on High Speed CAN network, nominal 2.5V (recessive) with pulses to 3.5V (dominant) on CAN High and inverse on CAN Low
Known-Good Waveform
Modern F-150s do not use a traditional VSS; vehicle speed is calculated by the ABS module from the four wheel speed sensors and transmitted digitally via CAN bus at 500 kbps. When monitoring CAN High and CAN Low together, expect clean differential signal with 2V peak-to-peak amplitude and proper recessive state around 2.5V when idle. Speed data is broadcast on the network every 10-20ms during vehicle operation.
Common Failure Patterns
No vehicle speed displayed, speedometer inoperative, transmission issues
Cause: CAN bus communication failure, failed ABS module not transmitting speed data, or multiple wheel speed sensor failures
Intermittent speed signal loss, erratic speedometer
Cause: Poor CAN bus termination, corroded network connections, or ABS module software fault
Diagnostic Tips
Use a CAN bus-capable scan tool to monitor PID for vehicle speed and compare to actual speed. If no speed signal, check all four wheel speed sensors first as ABS module needs valid inputs to calculate vehicle speed. Verify correct tire size and axle ratio programming in PCM as this affects speed calculation accuracy. Check for Ford TSB 22-2367 for speedometer accuracy issues on 2021-2023 models.
Related Diagnostic Trouble Codes
P0500P0501P0502P0503
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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