Speaker wires in a mobile environment must be installed and routed with care. The constant motion of the vehicle, foot traffic and shifting items in a trunk or storage area also present potential for damaged car stereo wiring. Speaker wires may be repaired using simple techniques, creating an electrical connection as secure as if the break never happened.
Identifying the Cause
Although you'll want to fix the broken speaker wire as soon as possible to resume listening, take the time to investigate why the damage occurred to begin with. Wires pinched in door jambs, leads that are too short and failure to protect the wires with a grommet or wire loom as it passes through sheet metal are all immediate causes. Look where the wires are routed. If the speaker wires lead to an amplifier mounted under the seat, make sure that the seat rail is not running over the wire as you slide forward and back. Amplifiers mounted to seat backs may become broken if the wire is too short and the seat is folded too far. Taking the time to investigate the potential cause of broken wires prevents you from having to repeat the process, while examining more critical wires such as power and ground helps you prevent similar issues that could cause a fire.
To perform a proper and permanent wire repair, basic but essential hardware is required. Insulated butt connectors crimp on each end of the break, restoring electrical continuity while providing protection against shorts circuits and a repeat of the problem. You choose these by examining the wire-gauge indications on the wire's outer jacket, whether 16, 14 or 12 gauge. A stripping and crimping multitool has wire strippers and crimping jaws all in one, allowing quick repairs. Have Phillips, Allen and Torx screwdrivers on hand if you need to remove a damaged portion of wire from an amplifier terminal. For added security, have a length of corrugated wire loom and electrical tape to secure the wire should it pass through or by a part of the car that could damage the section once again. Have these materials at the ready prior to beginning the repair.
Make sure the vehicle and stereo are turned off. Unscrew any speaker wire remaining in an amplifier using the correct screwdriver. Snip away the damaged section so you are left with two clean ends. Strip 1/2 inch of outer insulation from each end of the break. Slide one end of the wire into one end of the correctly sized insulated crimp connector. Place this into the appropriate crimp jaw on the multitool, normally color coded with the connector. Ensure the split in the metal sleeve on the connector is on the opposite side as the tool's crimping tooth. Squeeze firmly to compress the connector. Repeat the process for the other side. Give a gentle but firm tug on each end of the splice to test the strength of the crimp. There should not be any exposed wire visible at the base of the connector. If there is, wrap the exposed wire with two passes of electrical tape. Slide the wire into the corrugated loom if necessary, and provide a single spiral wrap of electrical tape to secure the wire inside. Turn the stereo back on and verify you have sound.
What Not to Do
Low-voltage applications such as speaker wires carry a only small amount of current, and do not require anything more than a properly-executed crimp. Electrical wiring in a vehicle with constantly twisting and moving panels is subject to stresses. As such, you should never simply twist the wires together, tape them and assume that the splice is secure. Soldering the wires back together is a possible solution, but it's not necessary and carries the risk of burning upholstery with the hot soldering iron. If you have to create an extension due to an abnormally large damaged section, do not use a smaller gauge wire than what is already in place. Doing so creates unnecessary resistance and potential signal loss.
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