Hey all, I've always come here to get help from the old threads but this is my first post. I'm trying to install an amp and sub using the factory head unit in my 99 GS 400. I don't have the Nakamichi one so it's the Pioneer I guess. When I got the car, the stock sub had already been taken out, along with all the wiring so I'm just assuming that the factory amp has also been taken out. To wire the amp, I pulled out the head unit and spliced into the following wires coming out of the head unit:

REM: Gray wire (I think thats the switched 12V wire)

for signal input, i used the rear speaker signals:
left rear positive - black wire
left rear negative - yellow wire
right rear positive - red wire
right rear negative - white wire

the signal wires i ran to a line level converter which converts to RCAs which go to the amp. The system isn't working though. did i tap into the correct wires? is there a different (proper) way to wire an amp using stock head unit? should i make sure the factory amp has actually been removed (behind the glove box i think...) I checked all the connections i'm kinda stumped on this one.

Also, what's a good way to get the wires into the trunk? I can't get through the back seat, right now the wires are going over the back seat and through the hole where the stock sub goes in the rear deck.

Sorry for the long post but I appreciate any help I can get. Thanks in advance.

 

You first need to look in the trunk for the amplifier it should be on the right side of the trunk underneath the cover. do the rest of the speakers in the car work with the stock deck.. If they do wire the LOC to the wires that went to the stock subwoofer its easier and the best way to run wires to the trunk is to take the back seat out, the bottom piece just lifts up with a little tug, then you might be able to squeeze wires through.

 

Here let me save you some pain and agony..
If you have the factory speakers working off the OEM deck you have the factory amp..

Drop your glovebox open (and the screws holding it in) About 8 or so phillips..
And then look at the main plug (its white) and tap into the 2 seafoam green wires. Seafoam Green with the red stripe is +..
Seafoam Green with the brown stripe is +

For your remote wire just use a OEM fuse adder (its like a fake fuse with a wire and a spot to put 2 fuses and one wire to crimp.....

And a good way to get the wires to teh rear are to take your backseat off and route it throught eh door sills..
Do not route the RCA wires and power wires together..

 

The pioneer amp is in the glovebox..
Here are some DIY's to help you.
http://bananags.grantham-international.com/ (I think there's one for the backseat) and glovebox

 

wow thanks for all the advice...

weewinn01 - there's no factory amp or wires anywhere in the trunk but I'll def take your advice on the back seat

lexusscturbo - thanks for the heads up on the wires, you wrote + for both wires but i think its safe to assume you meant - for the brown stripe. For the remote wire i'll look into that fuse adder if i get this thing working lol. Also, EXCELLENT link, def going in my favorites

I'll post an update once i have one....chicago winters suck btw thanks again guys

 

Yes I meant negative for the seafoam green and brown

 

Here is where you screwed up. You have to tap after the amp for signal. I would remove the back lid, I bet the wires are there tucked away.

 

Alright spent alot of time on this today and finally got it working! I was gonna run the wires under the arm rest like the banana GS link but I couldn't completely remove the arm rest. In the directions, he says you have to remove a screw or something under the steering wheel but I couldn't get that panel out to get to that screw so i couldn't remove the arm rest. Instead, I just ran the wires down the sides of the car. I also couldn't remove the back seat completely because i didn't have deep sockets for the two hidden bolts behind the headrests but managed to lift it up from the bottom just enough to get the wires through.

As for tapping into the wires, I was gonna ask about that, if it matters if you're before or after the amp. I removed the glove box and tapped into two wires, green with red strip and green with black stripe, BUT they weren't the wires coming from the amp, they were coming out of the orange plug thats on the left side of the glove box. I don't know why I didn't see the amp staring at me at first, those were the only wires i saw but whatever it still works.

Thanks again for your help guys, i really appreciate it.