Passing power cable through firewall

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.

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.