Toyota Nation Forum banner

1 - 3 of 3 Posts

254 Posts
Discussion Starter · #1 · (Edited)
A lot of people (including me) have had difficulty finding an entry point in the firewall for the thick-gauge red amplifer power wire. I spent a couple of hours trying to find a hole in the firewall, so I thought this thread with pictures might help someone else do it quicker with less hassle.

This is the broader view of the 09 Corolla engine drivers-side area, where the rubber feed-thru I used is located. This picture, from standing up and just looking in the engine compartment, kind of explains why it is difficult to find the rubber feed-thru at first. (When I finally found it, I marked it with a piece of masking tape so I wouldn’t lose it again.)

This picture is from the same angle as the first picture, but the camera was placed lower down from the top of the engine and closer. The spot I used is a round rubber wire-bundle feed-thru on the driver’s side of the engine. You can barely make out the red power wire under the uppermost hose, lower end, but you should at least see the black round rubber feed-thru gromet there.

Up close, here is another picture of the red power wire at the lowest point in the round rubber wire bundle feed-through. This feed-thru also has a cylindrical nipple sticking out, which allows for positive identification of the feed-thru. I cut off the end of the rubber nipple and shoved a coat hanger through the hole.

Inside of the car, I reached around under the dash until I felt the coat hanger, and chased it back to the rubber feed-thru. I marked the feed-thru location with a piece of masking tape, because it is easy to lose it’s position once the coat hanger is removed. The rubber feed-thru is pretty far up under the dash over the gas and brake pedals. I removed the coat hanger from the wire bundle feed-thru gromet.

I disconnected the car battery before drilling to minimize electrical hazzard risks from drilling into the car feed-thru wire bundle. I used a ¼” drill bit and drilled through under the feed-thru wire bundle from inside the car at a downward angle, and not to much penetration through the rubber feed-thru to avoid drilling into the wire bundle above the hole.

Routing of the rest of the power wire is pretty straight-forward and is covered in other threads.

I covered the exposed red power wire under the hood with corrigated-black-plastic wire split-loom sheathing, so the red power wire is protected from damage.

There are probably other places to run power wire through the firewall in 10th generation Corollas, but I was satisfied to find this particular one.

2013 Corolla S
2,765 Posts
Yes! I literally just finished installing a sub and amp using this same rubber nipple.

No drilling required.

Normally I custom make my wiring with 4 guage wire from the local audio shop and mount the fuse holders on aluminum bases, but the 4 gauge I had from my last car was already complete with soldered ends, so they would not fit through the nipple, the audio shops are closed for New Years and this is not a car I wanted to drill or cut into the grommet or get too crazy with.

So for this car, I decided to use the nipple and a packaged wiring kit. I cut about 1/2 inch off the end of the nipple, and used a 6 gauge Scosche all copper amp wiring kit that I got at Walmart for $35. The nipple was an absolut perfect and water tight fit with the Scosche kit. I did VERY lightly grease the power cable with connector grease (dielectric grease) to ease pulling the 15 feet of cable through. I also soldered the terminals onto the wire after crimping.

A full 4 guage cable would be a very tight fit.
1 - 3 of 3 Posts