Could be a loose cable (connection on the back of the speedometer). In today's electronics on cars it's best to take it to a mechanic who knows what they are doing for the repair. You might want to save the money, but if you mess something else up trying to fix the one thing it might cost you even more.
Faulty Vehicle Speed Sensor, faulty wiring, faulty input or output to the CECU (on certain vehicle types), faulty speedometer... you start by diagnosing to determine the cause of the problem, then you move on to how to repair it.
There are several common causes for a speedometer to stop working. Typically, these malfunctions are caused by an issue with a car's wiring, a broken gear in the speedometer system, a speed sensor issue or a faulty engine control unit.
Changing the tire size or changing the differential gear ratio changes the accuracy of the speedometer. The year, make and model vehicle will affect the answer especially if the speedometer is cable driven or electronic.
"Does he has to read" makes no sense. The sentence is "Does he have to read?"
The size of tires can effect that accuracy of a speedometer. Larger tires will cause the speedometer to read less than you are actually going.
Check the wires on the back of the rear axle. There is a sensor there for the speedometer. If the wires break, it will not read any speed or distance. I have had to repair mine twice. The sensor is on the drivers side of the differential to the rear. Hope that is it. Figure out the anti swaybar travel when you repair the connection to the sensor
Right around 107 MPH (Remember that your speedometer will read different)
instantaneous speed. =)
instantaneous speed
One of your wheel sensors are shot or your vss. Go to a repair shop and have them read the codes to see which one it is. The wheel sensors are cheap and easy to replace!
I ended up having to have a shop drill into it to get it out. Everything you read says they come right out, but mine didn't.
There are many PC repair courses online but you must find the right one. Some range from having you read a manual to giving you a video demonstration on how to repair PCs.
On the speedometer, no. It will indicate a speed but it will not be accurate.
At 60 mph the speedometer will read 58.1 mph.
A car has a speedometer. When you read the speed that it indicates, and you know the direction in which you're driving, then you know the car's velocity.