The third generation for the F-150 -- 1987 through 1991 -- brought about a redesign of the popular pickup's front end. Ford eliminated the old-style glass headlight assemblies in favor of more modern plastic lenses with bulb inserts. This allowed Ford to make the headlights set flush with theF-150's grille. When installing an aftermarket radio, or trying to trace an electrical problem within the 1989 F-150's audio system, knowing the color codes for the wires simplifies the process.
The 1989 F-150's radio requires two power wires to function correctly. One wire -- known as the constant power -- allows a constant flow of 12 volts to reach the radio to retain the radio's clock setting and station presets. The second power wire -- commonly called the switched power -- is what provides the electricity needed to turn the radio off and on with the ignition.
The constant power wire is light green with a yellow stripe. The switched power wire is yellow with a black stripe.
As with all electrical systems, the F-150's radio requires a good ground to complete the electrical circuit. Without a good ground, the radio might work, but it will not be at optimal performance -- squealing through the speakers, dim lights, low volume etc. The wire that leads to a good ground for the 1989 F-150's radio is red and it connects to the body behind the instrument panel.
The 1989 F-150's audio system has only two speakers from the factory; Ford mounted these speakers inside the door panels. The right speaker's positive wire is white with a light green stripe and the negative wire is black with a white stripe. The left door speaker's positive wire is orange with a light green stripe and the negative wire is black with a white stripe.
Both speakers have the same color of ground wire, but the ground wire for each speaker is bundled together with its respective positive wire.
If you are installing an aftermarket radio with a four-speaker output, you can add two more speakers and run new wires through the truck to the new speakers. If you are not using these outputs, make certain to cut any exposed wire off and tape the end of the wire with electrical tape. Failure to do this may result in failure of your stereo.
When you turn on the F-150's interior lights, the radio lights turn on as well. A light blue wire with a red stripe controls this process. If you are connecting an aftermarket radio, this wire is typically used to signal the radio to dim its display to avoid distracting you while driving at night.
The antenna wire is the thick, black cable that plugs into its own receptacle on the rear of the radio. The 1989 F-150's antenna wire has a standard size plug, so it plugs directly into the antenna receptacle on an aftermarket radio, if applicable.
