Component Testing: Speedometer
NOTE:
Tire size, wear and incorrect inflation can affect speedometer reading and odometer measurement. Allowable variance between actual vehicle speed and indicated speed is about 1/2 MPH for every 10 MPH of vehicle speed.
If speedometer is not functioning properly, disconnect vehicle speed sensor connector. Connect AC voltmeter (5-volt scale) between vehicle speed sensor connector terminals. With transmission in Neutral, slowly turn drive wheels. If voltage pulses are not detected, replace vehicle speed sensor. If voltage pulses are detected, check wiring. If wiring is okay, replace speedometer.