How to: Run Power Wire in your 4th Gen Nissan Altima Sedan

One of the most frequent stereo questions I see, regardless of vehicle, are those around installing an amp. One of the biggest parts of that process is running the power wire. I hope this how-to of that process will help you if you are at that step.

Tools required:

Phillips Screwdriver
Flathead Screwdriver
10mm socket wrench/ratchet
Box Cutter/Razor Blade

Step 1: Unhooking the battery

This is likely the most important step. Unhooking the positive battery terminal will prevent accidental shorting to the chassis, which can fry your equipment!

Using a 10mm wrench, loosen the bolt on the positive battery terminal, give the terminal a spin back-and-forth and pull the terminal off. Put the terminal to the side of the battery to prevent it from accidentally touching the battery lead during your install.
This picture shows the negative terminal being removed. The positive terminal is removed in the same fashion.

Step 2: Removing the Driver’s Side lower panel

Removing the Driver’s side lower panel is a good idea before you run wire through the grommet. While you can scrape by without, removing the panel (and a few accessories goes a LONG way to increasing the access to these tight spaces.

First, remove the cover to the left of the dashboard by gently sliding a flathead screwdriver into the crack until you can get a finger-grip on the edge. Pull the cover towards the outside of the car and it will ‘pop’ out.
Next, remove the fusebox cover to the left of the steering wheel to reveal a screw to the right of the fuses.
Once you have removed this screw, you can pull the lower panel off, first from the lower portion towards the seats, and then from the upper section.
Once you have the panel removed, we need to remove some wiring that is attached to the panel. First, remove the lower computer hookup by pushing down on the tab and pulling it out of it’s holder. Next remove, what I believe to be, the temperature sensor to the right of the panel by removing a single screw and pulling it off.
The only remaining piece is to remove the button panel and emergency key reader to the left of the panel. This is removed by using the tabs to remove any button wires, and unscrewing (2) screws, one on the top, one on the bottom. Pull this off and place it on the steering wheel column to get it out of the way.
For maximum comfort, remove the hood popper from behind the lower panel by unscrewing the (2) nuts that hold it to the bracket (10mm I believe).
Once you’ve got all of these components off, you should have easier access to the firewall location.

Step 3: Running through the firewall

While there are plenty of spots to run wire through the firewall, including drilling a new hole and installing your own grommet, there’s a great stock location that will accept the thicket wire you will likely run (1/0 ga). If I can offer any advice here, just be careful, you’ll be working in a tight space with a razor blade, and sharp edges all around. Most likely, you WILL scrape/cut yourself on something, much less if you get too hastey.

First you need to identify where the grommet is. Crawl up under the dash and look up, you will notice that the carpeting ends about a foot up into the firewall and there is some under-carpeting that goes up into the dash the rest of the way. Feel/look a few inches to the left of the Emergency Brake bracketing and you will feel a budge about the size of a tennis ball with some wiring coming through the under-carpet, that’s the grommet!
Get your bearings on where the wiring is coming out, grab your razor blade and start cutting around the grommet itself. There’s not a lot of wires running around the grommet itself, only through it, but be careful! I found the best ‘technique’ was to score a semi-circle around the grommet and then get my hands in there to pull at the carpeting until I had the grommet exposed. The under-carpeting is fairly thick, but it will come out with a few strategic cuts and some pulling and ripping.
Once you’ve got it exposed, again get your bearings on how the wire goes through, grab your razor blade again and cut a ‘cross’ into the lower section of the grommet. I found using the razor blade to get through a few layers and then using a phillips screwdriver to push through was a good technique.
Once you have your screwdriver pushing all the way through the grommet, you can start feeding the wire through. You won’t need a hanger on this one, the grommet is nice and pliable, so you should be able to feed it through from the inside. Once you have a foot or (2) through, walk around to the engine bay and look behind the air box, find your wire and pull your desired length into the engine compartment.

Step 4: Running wire down the driver’s side paneling

Now the wire is in your engine bay to the desired point, you can start running the wire to your trunk (or wherever you are mounting your amp(s)/distribution). Lucky you, the hard part’s over, most of the remaining panels will come up with just a bit of elbow grease, no tools required.

First, remove the running panels (both front and back) by sliding your fingers under the panel and pulling up. Once you have a clip up, slide your fingers down 6-12 inches and repeat until the panel is off.
Remove the driver’s side kick panel by sliding your fingers under the panel and pulling in towards the center console until the clips come out.
The middle pillar does not need to be completely removed. I opted to only remove the lower portion of the panel. Again, this is accomplished by sliding your fingers under the panel near the bottom and pulling in towards the seats. I believe there are (3) clips on the bottom that gave me enough clearance to work.
Now that our panels are out the way, you can start running your wire. For me, I chose to run my wire under & to the outside of the existing wiring. Just thread your wire where you would want to behind the kick panel though, it’s a good idea to use some zip ties to keep the cable in place.
If you haven’t noticed already, there are round clips going all the way to the back under the running-panels. You’ve got two options here: open them up like a clamshell or just run the wire through them like threading a needle. To open them, use a flathead screwdriver and pivot off of the top of the clip on the inner tab (I found a lighter touch worked best here). If you’re having trouble, no worries, there is enough room here to thread a single 1/0 ga wire with ease. Note that the center pillar will have to be threaded, if you did not remove the whole panel.
Once you’ve made it to the rear seat, you will want to lift the seat pan (the butt of the seat) to get the wire all the way to the trunk. The seat pan is easily removed by lifting it a little on the driver’s side and looking for a little pull tab. Pull it and the seat will come up.