How do I Install an Amp Power Cable?

By Blaze Johnson

i Hemera Technologies/ Images

External car audio amplifiers require adequate amounts of power in order to function and perform properly. The power output capability of your car audio amplifier will greatly affect the size of the power and ground cables needed for installation. Car audio amplifiers require an appropriately rated in-line fuse to isolate and protect the electrical power circuit. Running a power cable from your vehicle's battery to an external audio amplifier is an easy task, when using the appropriate tools and materials.

Step 1

Open the vehicle's hood and disconnect the "Negative" battery cable from the battery.

Step 2

Remove the interior rocker trim molding, located on the same side of the vehicle as the battery, using an appropriate screwdriver. Refer to a vehicle-specific repair manual for specific instructions on how to remove applicable interior components needed for the power cable installation.

Step 3

Remove the rear seat cushions to gain access to possible wire looms entering the trunk, if applicable.

Step 4

Examine the engine compartment firewall on the same side as the battery. Locate a suitable wire loom opening large enough for the power cable to pass through. If you cannot locate a suitable wire loom large enough for the power cable, drill a small 1/2-inch hole through the firewall, located away from any mechanical or electrical obstructions. Install a small rubber grommet in the hole to avoid damaging the power wire from the exposed bare metal.

Step 5

Feed the power cable through the firewall, from the inside of the vehicle. Pull the power cable up to the "Positive" battery terminal, providing enough slack to route the wire safely within the engine compartment.

Step 6

Route the remaining end of the power cable underneath the vehicle's carpet and rocker trim areas. Locate a suitable opening needed to route the power wire to the trunk area, if applicable. Run the power cable next to the amplifier, giving enough slack in the cable for proper routing.

Step 7

Cut off a 6-inch piece of wire from the cable on the battery side.

Step 8

Strip 5/8-inch of insulation from both ends of the 6-inch piece of cable and amplifier-side cable, using a pair of wire strippers or box knife. Install one of the supplied ring terminals on one end of the 6-inch cable, using a suitable pair of wire crimpers.

Step 9

Insert the remaining end of the 6-inch cable into one of the fuse holder terminals. Secure the cable to the fuse holder terminal by tightening the small setscrew, using an appropriately sized Allen wrench.

Step 10

Strip 5/8-inch of insulation from the cable end routed next to the amplifier and install one of the supplied spade or ring terminals. Certain amplifiers may feature setscrew power connections, similar to the type used for the fuse holder, eliminating the need to install ring or spade terminals.

Step 11

Disconnect the "Positive" battery cable from the battery. If your vehicle features "GM-style" side-mount battery posts, replace the factory battery post bolt with a battery post adapter, made specifically for car audio amplifier applications. Secure the power cable ring terminal to the outer connection stud on the adapter, using an appropriately sized wrench.

Step 12

If your vehicle features "top-post" battery connections, simply slide the "Positive" battery terminal bolt through the ring terminal found on the 6-inch piece of cable and tighten the connection, using an appropriately sized wrench.

Step 13

Check the amplifier power cable connections and fix any wire strand frays present. Secure the remaining half of the fuse holder to the cable leading to the amplifier. Connect the two halves of the fuse holder together, with the fuse installed.

Step 14

Secure the power cable with wire ties away from moving mechanical components and heat sources within the engine compartment. Replace the interior trim pieces and the rear seat cushions.

Step 15

Reconnect the "Negative" battery cable to the battery to finish the installation process.