Vehicle Speed Sensor
2021 Hyundai Tucson · 2.5L I4
Sensor Type
hall-effect
Waveform Type
pulse-width
Location
Calculated signal derived from ABS wheel speed sensors via CAN bus, no separate physical VSS on this vehicle - speed data comes from ABS module to instrument cluster and ECM
Pins
Unknown
Timebase
100µs/div for viewing CAN protocol
Voltage Scale
1V/div
Trigger
2.5V differential
Wiring
Not applicable - speed signal transmitted digitally via CAN High (Yellow/Blue) and CAN Low (Yellow/Green) twisted pair on CAN-C network
Expected Voltage Range
At Idle
2V to 3V
At Higher RPM
2V to 3V
Expected Pattern
CAN bus differential signal showing 2.5V nominal with 1V amplitude differential pulses between CAN High and CAN Low, 500 kbps baud rate on CAN-C network carrying vehicle speed data packets
Known-Good Waveform
Vehicle speed is transmitted as a digital value over the CAN-C bus from the ABS/ESC module to other control modules. The CAN bus should show continuous differential voltage activity with CAN High at 3.5V and CAN Low at 1.5V during dominant bits (2V differential). Speed data packets are transmitted approximately every 20ms with vehicle speed encoded as a 16-bit value in km/h.
Common Failure Patterns
Speedometer inoperative, no speed display, transmission stays in low gear
Cause: CAN bus communication failure between ABS module and instrument cluster/ECM, often due to corroded C300 connector behind dashboard
Intermittent speedometer operation or speed drops to zero randomly
Cause: Poor ground connection at ABS module or intermittent CAN bus wiring fault in underbody harness
Speedometer reads incorrectly but ABS functions normally
Cause: Incorrect tire size programmed in ABS module or failed instrument cluster
Related DTCs: P0501
Diagnostic Tips
Always diagnose ABS wheel speed sensors first if vehicle speed issues are present - the VSS signal is calculated from these inputs. Check for CAN bus communication DTCs in all modules. Hyundai TSB 17-BE-009 addresses speedometer/VSS concerns related to ABS module software - verify latest calibration is installed before replacing hardware.
Related Diagnostic Trouble Codes
P0500P0501P0502P0503
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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