So I finally got some 4 gauge wire in for powering my upgraded stereo system. I've decided to go through the rubber grommet in the firewall that the main wiring harness passes through (I don't want to be drilling holes). I've seen a few pictures from the stickies and searching, but I'd like a bit of advice from people who have done it, before I start mucking about with an exacto knife inches away from delicate wiring.

How did you cut a hole in the grommet for the wiring harness? What tools did you use? How long did it take, did you go from the interior or the engine compartment?

Any advice would be appreciated.

 

just poke a phillips head screwdriver through there, pull it out, and then feed the wire through that hole from the inside.

 

That's what I do..

 

I think it's better to drill a hole (on the passenger side). I wired it through the grommet at first, but didn't like the way the routing looked from the driver's side, so I drilled a hole on the passenger side firewall (there's a lot of space to do it too...just double check your clearance on both sides). You'll use less wiring too since the battery is on that side.

 

I think RotaryGod did a DIY thread on routing power wire..

 

I just used a bit of brute force to push two 4gauge wires through the side of the grommet (one for battery and one for ground) it wasn't THAT bad... but it wasn't exactly the easiest thing i've ever done...

 

I have not done this, but I work for a wiring company. The one thing you will want to make sure is that you seal your hole. You can get water in the grommet and the wiring and you will have a major mess. Use silicone to seal your hole. As for going through the driver side grommet, go the screw driver approach. do not us a knife. you will nick a circuit then get heat and a potential fire.

The other approach is to pull the voltage from an existing circuit within the car.
Here is where you can get the wiring diagram:
http://foxed.ca/foxed/index.php?page=rx7manual (at the bottom is the RX8)