The role of the speedometer is to measure the speed of the vehicle and give a visual reading to the driver.
The older speedometers were made up of wires and gears, but the modern speedometer is driven by speed sensors. If your Ford’s speedometer is not working, it could be anything from a bad sensor to a malfunction in the dial. A speedometer repair or replacement can be done in your own garage.
Here are some of the more common problems with speedometers.
The speedometer is no longer reading speeds. In an older speedometer that is cable driven, the cable could have broken. However, in a vehicle manufactured after 1990, the sensor could be bad and no longer sending the information to the speedometer.
The speedometer stopped working and the check engine light is on. Digital speed sensors can malfunction and no longer send information to the Ford’s computer. When this happens, your car’s computer is trying to figure out how fast you are going, and when it cannot find the data, it triggers the check engine light.
The speed sensor may need to be replaced. If the check engine light is not on, and there is no speed reading, you can test it by using the cruise control in your Ford. The cruise is on the same sensors, so if it is working, but the speedometer is not, the problem is in the speedometer itself.
The speedometer jumps or is erratic. This problem is the result of a speed sensor that is faulty, or if you have a cable speedometer, the wiring is bad. Either change the wiring or recalibrate the sensor to repair the speedometer.
You replaced your tires. Because the speedometer uses the factory tires’ diameters and radius as its calibration, if you change the tires to larger or wider tires, you may see erratic readings. It means that you need to recalibrate your speedometer to meet your new tires’ dimensions.
Replacing Your Speedometer Cable
- Take the engine cover off and notice where the cable enters the car. The speedometer cable is a thick, black wire that leads to the cluster.
- Remove the bolt under the dash. This allows you easy access to the old cable.
- Take the nut off the transmission in order to pull the cable out. Take off the clamps that hold the cable in place on both the engine and the transmission.
- Remove the old cable and put the new one on. Within the adapter, attach the square end of the cable. Tighten the rotating shaft nut.
- Feed the cable through and tighten its rear end bolt. Attach it at the square hold of the speedometer.
- Replace the clamps and engine cover.
Front Wheel Drive Speed Sensor Replacement
- Locate the speed sensor above the transaxle and behind the engine.
- Release the connecting hose, electrical connector and air cleaner above the sensor.
- Use a 10mm socket and remove the bolts that hold the sensor. Twist it out.
- Place a new o-ring on the sensor. Clean the flange and housing of the sensor before you reinstall it.
- Place the sensor back on the car and bolt it in.
- Reattach the connecting hose, electrical connector and air cleaner.
Rear Wheel Drive Speed Sensor Replacement
- Place the vehicle on a flat surface.
- Locate the speed sensor behind the transmission on the driver’s side.
- Jack up the driver’s side.
- Take the wheel off.
- Keep the sensor in place while using a socket to remove the electrical connectors and bolts.
- Carefully remove the sensor.
- Place a new o-ring on the new sensor before putting it back on the car.
- Reattach the electrical connector and tighten the bolts.
Your speedometer problem may not be mentioned here since there are other things that can go wrong with sensors and electronics. If you find that the problem you are having with your Ford’s speedometer is not mentioned here, you may want to take your vehicle to your local dealership.