Hi,

New here, first post, I looked around and couldn't find an answer to my question so here goes...well actually, let me explain first.

I picked up a 4 channel amp and I want to amp the front door speakers, and rear deck speakers, the only problem is, I don't know how to do that. The stock head unit has no rca, so I have to tap the stock amp in the back (I have stock bose setup with the stock amp at the moment). I just need to know which wires to tap besides the amp turn on.

Also, I'd like to move the amplification from the rear deck to the rear doors (the stock amp, not my 4 channel)

I've wired amp and sub before, but never a 4 channel amp to speakers.

So basically I'm asking how to wire a 4 channel amp off the stock HU to the front doors, and rear deck.

Thanks,

Nick

P.S. after i successfully wire all this jazz and I decide to get an aftermarket HU, if i get the harness and the amplifier integration harness it shouldn't affect my setup right?

Thanks again. and hopefully I made sense...

 

all '98s to the best of my knowledge dont have any amp preinstalled in the car. you would have to wire it like any other car, splice it inline with the speaker wire. the problem would be the stock speakers sometimes blow (rattle loose) out even with the stock head unit. i would not amplify them without upgrading the speakers first. they were made for stock power levels, i doubt they would handle too much more power.

remember- when you change out HU's your OBD port often stops working. search for more information about that. but it means whenever your CEL comes on or emissions places try to plug into your car, your SOL. its pretty random as to which brands/types of HU's actually do it, sometimes it still works, sometimes it doesnt.

 

In order to hook up a 4-channel amp on the factory head unit you need what's called a "premium" line output converter (LOC). This allows you to splice into the factory speaker outputs in the back of the radio and output them into four RCA pre-outs. As for how to do the wiring, you have a couple of options: 1) you could mount your amp, run the RCAs to the head unit, and then run speaker wire directly from the 4-channel to each speaker you want it to power; this is the hard way, but fail-safe. 2) wire the LOC to the back of the head unit, locate your factory amp (I know for a fact that some 98 models have a small amp that is directly attached to the rear left speaker) and catch your speaker wires there instead of running them all around the car. Either way you're essentially bypassing the factory amp. As for changing out the head unit, no worries there. The OBD is only messed up if you wire the amp turn-on wire (blue/white or sometimes just solid blue) in the new wiring harness. There is what is called the "K" wire which lines up with the pinning of the amp turn-on and, if connected, will interfere with the functioning of the OBD. Just don't hook up either the blue or blue/white wires coming off of the aftermarket head unit into the harness that plugs into the car and you'll be good to go.

 

so i've replaced the front door speakers and rear deck speakers because I figure A) The ten year old speakers have seen better days, and B) I want to amp them without worrying about popping the factory ones.

I did the fronts and all is well, but tonight I did the rear deck, took out the bose, took the spade clips off of the, attached them to my new ones, foolishly i re-mounted them back onto the deck before I tested them. Now my rear deck and front doors dont work...It doesn't make any sense to me because if the rear deck was completing some kind of circuit, wouldn't the new ones be doing the same thing? any help would be greatly appreciated.

 

Problem isn't about completing a circuit, it's that your head unit is still looking for those Bose speakers, and rather than risk running speakers it doesn't recognize and could potentially damage, the car just cuts off all the speakers. What you need to do is bypass the factory amp. Try unplugging the side of the amp that goes from the amp to the head unit and the other side going from the amp to the speakers. Jump the wires for the rear speakers (if you don't know which they are the colors might match up to the wires at the speakers, if not then you can use a 'C' or 9-volt battery to test the wires and pop the speakers) from one side to the other, bypassing the amp and see if they come on then. Another reason why your system cut off could be that one or more of the speakers are grounding out. If you can and know how, perform a continuity test on each of them. If not then visually inspect them and make sure none of the wires are grounding out and that none of the terminals on the speakers are either. This would actually be much easier if you just went ahead and replaced the head unit first, seeing as how a premium line output converter to add the four RCAs you'll need costs around $100 anyways.

 

yeah i plan on getting a new head unit, im just waiting for my dash kit and harness to come in

 

so i put in a new headunit, but my rear deck speakers still aren't working. im sure they aren't grounding out because the contacts aren't touching metal, and i dunno. im stumped.

 

Does your new head unit have RCA inputs for 'rear'? If so then you might be able to just splice some male RCA ends onto the speaker wires coming from the harness and plug them into the 'left' and 'right' rear channels on the h/u. I'm guessing that those speakers are low-level inputs, and your h/u is putting out a high level. Using the RCA's should allow your h/u to output in a low-level.

 

some one told me to buy a line level adapter which will convert speaker sound into RCA. heres a link

http://www.legacycaraudio.com/itempage.asp?model=LN60

 

Umm.. well, why would you insist on keeping your OEM headunit? It's from 1998, a lot has happened since then, sound has gotten better, you can play mp3, connect your ipods, use bluetooth, they have bigger screens, better menus and better EQ solutions. I can't recommend using a lineout converter, it will just be another source of sound degrading.
I'd recommend buying something with atleast two pairs of line out (you need three if you want to expand with a subwoofer later).
I've done complete audio rewiring in 3-4 A4 B5s by now, just ask if you're wondering about wiring schematics or anything like that!