Aside from the fuel gauge, the speedometer is the most important instrument for vehicles operated on public roadways. A properly operating speedometer is necessary to ensure that the vehicle is operated within the speed limit, but also to ensure that speed warning signs can properly be adhered to. Although speedometers are simple in design, problems can still develop. The most common speedometer problems include a needle that either fails to register any speed or a needle that moves erratically. Thankfully, changing a speedometer is fairly straightforward.
Disconnect the negative battery cable from the battery with a wrench to prevent electrical shocks.
Disconnect the instrument panel from the dashboard. Instrument panels use a series of retaining screws that hold the instrument panel to the dashboard. These retaining screws are typically located on the lip of the instrument panel. Remove the screws with a screwdriver, then pull the instrument panel towards the steering wheel until the speedometer cable can be accessed.
Remove the speedometer cable from the back of the speedometer with an open-end wrench. There is a single speedometer cable that uses an integrated nut to attach to the speedometer. Using the wrench, twist the integrated nut in a counterclockwise direction until the nut is loose, then pull the speedometer cable away from the speedometer.
Remove the lights and any other electronics from the back of the speedometer. Except for very old speedometers, all speedometers utilize at least one light to illuminate the speedometer when the vehicle's headlights are turned on. To remove the light(s), pull the metal cone that surrounds the light straight out of the back of the speedometer. Some light assemblies must first be slightly twisted before being pulled to unlock them.
Replace the speedometer. Removing the existing speedometer is simply a matter of removing the small retaining screws from the back of the speedometer. These screws hold the speedometer to the back of the instrument panel. Most speedometer retaining screws are very small, and may require the use of a jeweler-sized Phillips head screwdriver. Once the speedometer has been removed, position the new speedometer against the back of the instrument panel and install the retaining screws.
Connect the speedometer cable and the electronics to the back of the speedometer. Install lights and any other electronics first, since it is easier to access the back of the speedometer with the speedometer cable disconnected. Connect the lights and any other electronics into the speedometer, then insert the speedometer cable into the back of the speedometer. Tighten the integrated nut on the end of the speedometer cable with an open-end wrench.
Position the instrument panel into place within the dashboard, then install the instrument panel's retaining screws. Connect the negative battery cable to the negative battery post with a wrench to complete the replacement.
