How to Wire Up a Car Speaker System

by David Lipscomb Google

    In many vehicles -- irrespective of price -- the speakers in the stock audio system get short shrift. However, the aftermarket is filled with every level of quality and price point you can imagine, allowing you to wire new speakers in your car or truck. Although nearly every vehicle has thin speaker wire running to the doors, this too can be upgraded to offer a fuller sound and greater power transfer. When these improvements are complete, your vehicle retains its factory look while offering vastly improved sound.

    Wiring and Supplies

    A new wiring project involves a few key tools and parts that, while simple, are necessities. You'll need a socket wrench, wire crimper/stripper combination tool, insulated crimp connectors matching the gauge of wire you choose, Philips, Allen and Torx screwdrivers and wire push tool. A device called a panel popper gets under the clips and pins securing the door panel to the sheet metal, reducing the chance of breaking the plastic retaining hardware. For connection to the radio's wiring harness, T-tap connectors splice directly into the wiring without having to cut it. For most vehicles, 16- or 14-gauge speaker wire is acceptable, given the relatively short distances from the stereo to the new speakers. All of these supplies are available at your local electronics store. Source a vehicle schematic to locate the multiple screws, pins and clips holding panels and trim to the dash and door, as well as various wire locations. These diagrams are available from vehicle manufacturers, online installation sites and -- sometimes -- the back of your vehicle owner's manual.

    Radio Access

    Remove any screws securing the trim around the dash in place. Set these into a nearby cup holder or a plastic baggie for safekeeping. Gently pull off the trim using the panel popper and set it aside. Remove the screws securing the radio bracket to the dash and pull out the radio. Look at the label affixed to the top of the stereo to determine which wires leading from the harness pertain to the speakers you intend to replace. Each speaker pair has four wires. The left and right speakers have different colored wiring, with one wire featuring a black or white stripe.

    Panel Removal

    Follow the same procedure used with the radio trim, removing screws and using the panel popper to loosen the door panel. Gently pull away the panel, peering inside the gap between the panel and the sheet metal for the various wire harnesses powering locks, lights and windows. Release these with your fingers and then set the panel aside. Remove the screws holding the stock radio in place. If present, pull off the speaker wire harness connected to the speaker terminals. Leave this intact for a quick reversion to stock later on when you sell or trade in the vehicle. If the stock speaker uses a detachable spacer to ensure window clearance, pull this off for use with the new speaker.

    Radio Wiring

    Remove the negative battery terminal wire under the hood using the socket wrench with the appropriate insert. Clamp a T-tap connector over each of the speaker wires on the wire harness, making this connection as close as possible to the back of the radio. Secure each clamp with a pair of needle-nose pliers until the two halves click together. Measure and cut a length of speaker wire for each speaker location, adding roughly 20 percent to the length to ensure you have enough slack. Strip 1/2 inch of insulation from both conductors of each wire at the radio end. Crimp the male spade component of the T-tap connector to each conductor. Push the spades into the slots at the base of the clamp half of the connector, until it pops into place. Repeat for every speaker. Drop the wires behind the dash, but don't push the radio back in just yet in case you need to troubleshoot later on.

    Speaker Connections

    Pop off the sill plates and kick panels to gain access to the wire chase, located under the doors in most vehicles. Note that you probably won't have to remove the sill plates if you're only wiring the front doors. Push the wire through the rubber boot protecting the stock door lock and window wiring leading from the cabin into the door panel. Pull the wire to the speaker opening. Strip away 1/2 inch of insulation from both conductors on the wire. Crimp a female spade terminal to each conductor. Slide the spacer, if present, onto the back of the new speaker and then slip the wires onto the speaker terminals. Screw the speaker to the door using the original screws. If the new speaker includes a rubber gasket, stick this to the back of the speaker basket to aid in vibration reduction before sliding on the spacer. If you're upgrading the rear speakers, grip the wire with the wire pusher and carefully route it from the front of the vehicle to the back doors through the wire channel. The remainder of the process is the same.

    Cleanup and Testing

    Attach the negative battery wire. Turn on the stereo, adjusting balance and fade to ensure all speakers are receiving signal. If you don't hear signal from one or more channels, check the wire connections at each speaker and behind the radio. When you're satisfied all is well, return all panels to the sheet metal and around the radio. Vacuum up any wire shavings and insulation clippings from the interior.

    About the Author

    David Lipscomb is a professional writer and public relations practitioner. Lipscomb brings more than a decade of experience in the consumer electronics and advertising industries. Lipscomb holds a degree in public relations from Webster University.

    Photo Credits

    • Photodisc/Digital Vision/Getty Images