Passing power cable through firewall

I did a search on this but could not find an answer, so...

I own a 2000 Chevy Tahoe (new body style) and need to run a power cable (wire) from the battery to power my amps. I'm using a Rockford Fosgate wire kit for my cables. I would like to find out if someone knows of a good spot to run the cable (wire) through the firewall and also let me know if I may need to dril or cut a hole in something to do it. I'd prefer not to drill a hole but if there is no other way, then I'll have to deal with that.

Thanks.

Good suggestions nouse...as usual.

What I would do first before drilling is get up under that dash and see where other exsisting wires and stuff go through. If I find a suitible "grommet" I CAREFULLY slice with a razor knife and slide a "fishing tool" into it. (A long azz zip tie works wonders).

I catch it under the hood, tape the amp wire to it, lube it up so it slides back in easily.

Now, if you need to drill be ultra careful. Nouse is right to leave this to a pro. However, what I do is look at the firewall from the inside and see in relation to the brake pedal, where the throttle cable goes thru, bolts etc. to get a good idea where a safe and accesible place to run the wire is.

I start with a small 1/8'' bit and carfully drill without pushing to hard. You don't want to poke anything..it's a nightmare. Once I am through I either shine a light on one side and look on the other for it..or slide a small wire thru the 1/8'' hole to see exactly where I am. If you were extra careful with the earlier steps..all should be well and drill for size....use a grommet. Don't want no blown fuses down the road. If you messed up, seal the hole with silicone and repeat process. Remember, if you can't see light thru the first layer..don't go for the second unless you know for a fact whats behind it.

Good Luck

Thanks for the suggestions. When the sun comes up again, I'll look to see if the wire will fit where the other wires are and/or search for a good possible drill spot. I'd prefer not to drill and I like my vehicle so it would be the last resort.

Thanks and I'll keep yall updated on the situation.

On that vehicle the grommet for the main wiring harness through the firewall is pretty large with a lot of room in it. It is a double walled grommet.   What you can do is put a small slit in it just large enough for your power wire and then push a dull object (so that you do not risk cutting into any of the wires in the harness) into it in order to put pressure on the inner wall.  You may need some one to hold pressure on the inner wall while you reach in from the inside (directly up from the junction box and slightly to the left) and seperate the inner wall from the outer.  Once this is done it is very easy to run your power cable through the firewall.

If your power cable is small enough you may be able to drop it through the emergency brake cable grommet directly in front of the drivers seat, run the wire over the frame and follow the main harness up into the engine compartment to the battery.  From that grommet forward it is only about a 6inch run to the main harness.

I have another question regarding this vehicle (2000 Tahoe).

I noticed it has 7 speakers total. One speaker on each door with two tweeters and a subwoofer in the cargo area. Playing with the fader on the factory stereo, I noticed that the tweeters in the cargo area were fading with the rear door speakers, the front door speakers were for the front, and the subwoofer didn't fade at all.

When I replace the factory stereo, will the speakers in the cargo area cease to work? I don't believe there is a factory amp, but I don't know for sure because there is no real power coming from the system. I don't believe the original system is a Bose system because Bose isn't displayed anywhere in the vehicle.

I know on some of those trucks there is a strange system where the front and rear speakers are on deck power, and the rear doors are amplified and crossed over for bass only. Play the system and put your ear by the back door speakers. If you only hear bass you have one of those systems.

The sub not fading is normal.

Thanks for the reply. When I was playing with the fader earlier, that's when I noticed how the system worked. Driver door and front passenger are the "front" of the fader. The speakers on the passenger doors behind the driver and front passenger AND the tweeters in the cargo area are on the "back" of the fader. The woofer is non-fading. I call the tweeters in the cargo area tweeters because there is no bass coming from them; the bass is only coming from the very low powered sub in the cargo area.

My semi-concern is to still have all the speakers working when I change the deck. I guess I'll find out when I hook up the harness to the aftermarket deck.

I don't know the impedence of any of the speakers in this vehicle but if the rear passenger door speakers and the speakers in the cargo area are all hooked up to create a the something equal to a two channel 4-ohm load, I guess that'd be ok. I guess in the end, I'd still want all the ability of all 7 of the speakers working. Then again, I don't care about the subwoofer working but I do care about the tweeters in the cargo area.

I don't really want to take it apart to look at the wiring. I have a basic wiring diagram from a Haynes service manual (the kind they sell in auto parts stores) but it seems a bit confusing to tell. I'll try to take a picture of the diagram.

Heres a trick I remember. If it's a bose system for some reason (like you noticed) it is not identified anywhere. However, when you first turn the deck on, it will say Bose on the display screen for a short time.

Regardless, it appears you have an amplified or partially amplified system. What I have done with those in the past is grab the rear door wires at the sill area. Then I use a 4 channel 2 ohm stable amp.  I run the front doors and rear doors together to the front channel and the rear cargo area speakers to the rear channels (makes alot more sense IMO)

Now if you don't plan on using an amp you might be best not using the rear door speakers..the front and rear cargo wires are at the deck area, I have not  yet figured out how to integrate with the factory amp on that particular system..it's just strange basically.

as far as the rear sub if you hook up the remote wire in the factory harness it might play high level but probably a better idea to use a "real" amp/sub for much better output, SQ and reliability.

Keep me posted.

Thanks for the reply.

My plan is to use the deck power on the doors for now and put two 12s in the back in a box making the factory sub redundant. The wiring that caused me to start this thread is for the amplifier, which happens to be a MTX Thunder421D 210W x 1, to push the subs. I'm also prewiring the power and ground wires (without fuses) to the vehicle for when I have the funds to purchase a 4 channel amp for the other speakers. The deck I have has 3 preamp outputs, one for subs, one for front, and one for rear. I just came up with an idea, tell me what ya think....

I can use components for the front and rear except for the rear, I can put the tweeters where the current tweeters are now in the cargo area and put the mids in the passenger door. Nah, now that I think about it, doesn't seem like a good idea. I'm beginning to over think!

yeah, for best sound keep the mids tweets close together.

Should be no problem doing it that way until you get your 4 channel. I am pretty sure the speakers in the back are more then just tweets, perhaps components or a small mid. Have you checked back there yet?

I haven't checked them out yet in the cargo area, I will do so in a couple of days. I did get bored and looked for a hidden amp somewhere and decided to look behind the glove box. I ended up taking a blurry photo of this:

So, do you think that is the hidden amp that is helping power all these speakers?

Could be, looks like it has factory amp/speaker wiring to me.

Regardless, it does not look like anything critical such as SRS or any kind of control module so I would suggest this...

With the vehicle off, unplug one the harness plugs. Turn on the vehicle, turn on the stereo and see what is or isn't playing. If all is still playing turn key off and reconnect. If any speakers stop playing you found the hidden treasure. You can acess the speaker wires off that amp and run them to the dash or to the location where your aftermarket amp(s) will be installed.

Keep me posted. If it is an amp I will tell you how to determine what all the wires are.

master5 wrote:

---

yeah, for best sound keep the mids tweets close together.

---

great suggestion but this does not always yield the "best sound." In fact many SQ vehicles have the tweeters mounted in the a-pillars and the mids in the kicks. this yields for great soundstage and stage depth.

Agreed in certain applications killer however speaker placement as far as sq vehicles staging depends on other factors aside from placing the tweeters in the a pillars. On most of the comp vehicles I put mids/tweets in the kicks and use a seperate center channel with a spacial control and attenuator.

If you think about how directional tweeters are, and when in the pillars for example on the drivers side the left tweet is alot closer to you then the passenger side. By placing the tweets in the kick you won't be in the center of the sound stage, but will be closer to centered due to the increased distance vs a door or pillar. I have found in some cases a seperate center channel is not even needed, the positioning of the mid/tweet yeilds a really good stage on its own.

This is why the most extreme of comp vehicles either center the seat, or move them as far back as possible.

But this is not to say in every vehicle it will hurt the sound quality by placing the tweets in the pillars. Reflections, shapes and materials, power, phasing etc all have some affect on sq, good or bad.

But as far as what murdakillemall was thinking about doing was using a component set and place the mids in the back doors and the tweets all the way on the rear pillars. I can't imagine that sounding very good.

I ended up utilzing the factory amp and my external amp. The stereo is wired to the factory amp to allow all 7 other speakers to work while the external amp is wired (of course) to handle the two 12s. I prewired it for additional amps from the stereo but I probably won't use them as it gets pretty loud. Once I replace the speakers in my box (and maybe even the box) I'll decide what to do for the amp, either get another mono amp or purchase a 2 channel amp.

But as far as it sounds now, it's doing what I want it to do.

Cool, just make a better connection..wires falling out sux..lol

How did you interface the factory amp? Did it use a standard harness with remote on to it, of was any kind of interface or adaptor needed? Jus curious.

Thanks

I used the factory amp by connecting the remote from the deck to the remote on the wire harness, just the standard harness. No other adapter was necessary. I was going to get a amp bypass harness but not now, since all of the speakers are working, even the 8 inch sub that I don't even care about heh. The reason I wanted a new box is because the box I have now is a bandpass box and I think I want to go with a regular ported box.

That's something I need to figure out though...