Power Wire Through Firewall

[Hives]

How can I run a 4 gauge power wire through the firewall without having to drill through it? Also, would an Optima red top battery be compatible with a 2006 Mazda 3? Please help me! I need to continue my audio project.

[TheProfessor]

I ran my 4awg wire through a pre-existing hole in the firewall. There is a cable running through a hole with some spare room up behind the pedals. I just used a coat hanger to force the wire through and voila, no drilling. Truth be told though, it was a bitch to do, but worth it as I didn't want to have to drill.

As for the battery, I wouldn't know, but I'm sure you could just e-mail Optima.

[MPS]

Yellow Top for audio ... and if ur not sure how to run ur power wire then i don't think you should do ur own system ....

[Flagrum_3]

Hey MazdaSpeed everyone has to start somewhere!, don't discourage him.As for Optima batteries...I've been searching also, but I don't think they build one to fit our 3s yet....If you manage to find it please post it.

Thanks,


_3


.

[MazdaTree]

Go run a search on m3f, Im pretty sure I saw a few ppl with the optima batteries in their cars... I think they just had to put a piece of wood under to keep it secure, because it wasn't tall enough. Jeff from Lockdown reccommends the blue top (marine) because it has the most cold amp cranks or something like that.

As for installing your own system it's pretty easy.
To run the 4 gauge wire is even easier.

You can either
1) Fit it through the hole alittle on top of the brake pedal (small hole)
2) Make a hole in that huge gromit on the passenger side with a hanger then run the wire from behind the glove box.

[EvilEric]

http://www.mazda3forums.com/index.php?topic=33092.0

This one has alot of details on locations to run wires through. I think everyone uses the gromlet by the door.

[MazdaTree]

http://www.mazda3forums.com/index.php?topic=33092.0

This one has alot of details on locations to run wires through. I think everyone uses the gromlet by the door.

Yea, it just fits 4 gauge... Everything under 4 gauge doesn't fit...

[KeithB]

I may be late in posting this...
If you remove the glove box, 2 screws under trim strip, you have easy access to a large grommet that passes a cable harness through the firewall.
As for number 4 wire, it seems a bit excessive!
Unless you have a HUGE amp system , #8 will probably work and is easier to handle.
Or.if you must, use 2 #8 cables...again, easier to handle.

Also, I have found that a ground wire run from the rear of the head unit helps with buzzzzzing ignition noises.

[cereal83]

I just installed an amp in my car on the weekend. It was the worst install I ever had to do. I was trying to get 4 awg through the hood release hole but that never worked so I went with 8 awg through the same hole and it worked. If you have enough cable, there is a nice big hole behind the glove box on the passenger side!

[KeithB]

The 3 is definately the toughest car for wiring through the firewall I have run into.
It's quite easy to get the glove box out.
Just remove the 2 screws that are under the dash trim strip and the whole box "drops" out.
Oh, and remove the box light assembly.
Then, it's dead easy to get to the the hole for the wiring harness.
Lost of space for wiring.
It is the best car for working in the dash once the glove box and radio are out.

[TheProfessor]

I had no choice but to use 4AWG but I managed after a lot of swearing and getting my wife to help me to get it through the hood release hole. I didn't know about the hole behind the glove box, probably would've saved some serious aggrevation!

[garboui]

The 3 is definately the toughest car for wiring through the firewall I have run into.
It's quite easy to get the glove box out.
Just remove the 2 screws that are under the dash trim strip and the whole box "drops" out.
Oh, and remove the box light assembly.
Then, it's dead easy to get to the the hole for the wiring harness.
Lost of space for wiring.
It is the best car for working in the dash once the glove box and radio are out.

i have to disagree with that especially iy its an automatic. when i did my system i ran 4awg(excessive for my setup but i have upgrade room). i took out my battery and drilled a 3/8" hole in the back of the battery box. the fuse holder has plenty of space to live in the batt box as well. ran the power cable out the back of the box and down a few inches. on the ATX cars there is a nice square plastic cap that fills in the hole where the clutch would normally go. w/o having to take out the plug its easially excessable fomr the inside to run drill another 3/8" hole. 4awg wire fits snug in this hole so having water come through shouldnt be a problem. then from here its easially run down the drivers side to the rear. unless you look under the dash or inside/behind the battery box its impossible to tell that there is anything installed.