On a mechanical speedometer, a worn cable could lose its ability to spin the way that it needs to, interrupting the chain reaction process that gives you your speedometer reading.
On an electronic speedometer, a faulty speed sensor could prevent it from working properly. If the VSS isn’t working, your vehicle doesn’t have a way to measure how fast the driveshaft is spinning to calculate your speed. Because it can’t determine vehicle speed, this can also prevent your cruise control from functioning.
Regards,
Rachel Gomez