The speedometer cable is bad. It has a kink or a break in the line. I was guess a break from what you are describing.
Our odometer/tripmeter also just stopped working at 220,000 miles. This is an integral part of the speedometer assembly, and cannot be repaired. The entire speedometer must be replaced.
check to see if vehicle speed sensor is bad. it will show up on computer scan that can be done at autozone for free.
Probably has a short or a bad connection.
If by 'set' you mean to match it to an old speedometer's settings to read proper speeds, look on the back of the speedometers and you should see a group of small switches. Make sure the switch positions on the new speedometer match the positions on the old speedometer. Assuming the old speedometer was set correctly to begin with, the new one should now read your speeds and mileages correctly. If it doesn't, contact your local Dodge dealer, they should be able to find the correct setting for your vehicle (they will likely need to know the VIN first).
The speedometer cable on a 1987 Mazda 323 is located on top of the transmission and travels up to the dashboard. It helps the vehicle's computer monitor speeds constantly.
you are changing speeds
Possibly your speed sensor. My speedometer would bounce around & then soon after it felt like my transmission was slipping. Turns out the speed sensor controls the upshift in your transmission.
usually your speedometer, odometer, and trip doesn't work. It also may trigger check engine light with the O\D OFF blinking. I remember this happened to me . it went away when I turned it off. But came back when I hit Hwy speeds, usually and simultaneously when I let off the accelerator abruptly. Order and replace Transmission Vehicle Speed Sensor.
check the speedo cable and see if it needs to be lubed. if car has cruise control, it will have a upper and lower cable.
Broken Speedometer cable. Does the engine run slightly erratically when you drive slowly? If so, your speed sensor (VW calls this the VSS) is at fault. Another option is that the plug that attaches to the VSS is loose or has a bad electrical connection. The erratic behavior is due to your fuel injectors not knowing how fast you're going, among other things, so they can't inject the right fuel mixture. If it's not the VSS, then it's the wiring from the sensor to the instrument panel. The speed sensor is directly wired to your odometer at the instrument panel in the drivers side dash before it goes anywhere else. The VSS signal leaves the instrument cluster (and the odometer in it) for the fuel injectors or where ever else is it needed before it comes back to the instrument cluster and ends up in the speedometer. This so that if you try to "fool" the odometer to not know if the car is moving or not (by cutting the wires, for example) the car won't run well (drives erratically when going at slow speeds.) Since your odometer is not working, the problem can be traced to somewhere between the odometer and the VSS. Try to find this sensor and make sure the plug with the three electrical contacts are solid and there's no oil or crud preventing electrical contact.
1 Mile equals 1.609344 Kilometer. Also, if your speedometer is strictly in Kilometers Per Hour, the same number is used. Here's some values for the more common speeds. 35 mph - 56.3 kh 55 mph - 88.5 kh 60 mph - 96.6 kh 65 mph - 104.6 kh 70 mph - 112.7 kh 75 mph - 120.7 kh Enjoy!
The speedometer does not take into consideration the size of the tires. It measures the rpm's of the transmission or differential. **incorrect, the speedometer uses a predetermined constant based on the circumference of the stock tire diameter multiplied by the number of revolutions** I suggest driving alongside a friend who can signal you when his speedometer reaches predetermined speeds according to the speed zone and check your own speedometer to determine the speed you need to drive for that speed zone. Do this on a rural road with no oncoming traffic to avoid any accidents.