Car Stereos: power wire, self tapping screw, clutch plate

Question
i have a extened cab silverado. tryin to put a subwoofer in it. running the power 12v cable for the amp and it is giving me a hard time. where and how do you run the power wire threw the fure wall.

hope to hear from you..

Answer
Hi Trey,

On the full-sized GM trucks and SUV's, I usually drill a hole in the firewall's "clutch plate" area.  This is a spot on the firewall located under the driver's side dash.  You can locate it by looking for a circular cutout in the rubber firewall liner under the dash.  Remove the cutout, and there will be a clear spot in the metal underneath that can be drilled.  Be sure to protect the wire from sharp metal edges by using a grommet or bushing, and seal the hole afterwards so water can't run into the cabin along the power wire.

If your truck is equipped with a manual transmission, this part of the firewall will be occupied by the clutch assembly.

You can also find a large bundle of vehicle wiring that runs through the firewall near this area.  It might be possible to run your power wire along with this wiring.  However, I've always found it easier just to drill a new hole.

The best way to drill through a firewall is with a step bit or "uni-bit".  A good trick is to use a self-tapping screw to make a small hole in the firewall before you use the drill bit. Then you can locate the hole, and make sure there's nothing on the other side that will be damaged by drilling.  You'll find it easier to drill from the inside of the firewall, instead of the engine side.

Hope this helps!

Brian