How to: Wire in Factory Sub to Aftermarket Stereo

[phillypremiere05]

or you could just order the wire harness from crutchfield like i did for $25

 

[rgalka]

Well actually no... I did get the radio from Crutchfield so I got the harness... but it does not support the sub woofer. I originally got the harness that uses the Ford amp so that the sub woofer would function, but every time I switched sources or even radio stations I got a loud pop from the speakers. They told me that my head unit was putting 12v on the amp turn on wire an that the Ford wanted 5v so I built a voltage converter on the line with no effect. Turns out that fix is only for popping when first turning on the car... So they switched out the harness for one that by passes the amp. And like I said that harness does not include the subamp.

Bob

 

[The Star Thief]

OK. So to sum up:
1. I need to get the power down to 5 volts from the new HU
2. Connect the HU sub out RCAs to the stock sub by either splicing or dicing

So if this is so simple why does every stereo shop I go to tell me it's impossible?

 

[rgalka]

Hey Star Theif...

So what is it that you have and what are you trying to do?

I found that the 12v to 5v conversion isn't necessary. (at least in my case) If you are getting a pop from the speakers when you turn on the ignition and the radio comes on with a pop then yea you might need that.

this is the circuit that you can build
http://electronician.blogspot.com/2009/11/12v-to-5v-dc-converter-using-7805.html

for capacitors I used 10uf 35v on both the input side and the output side. Use a heat sync. I tested this out and it did work as far as voltage reduction... but it didn't fix the problem I had with I was using the Ford amp and sub amp. If you are bypassing the Ford amp you don't need since the Ford Sub Amp uses 12v for the turn on voltage.

So... what do you have and what are you tring to do?

Bob

 

[The Star Thief]

I've got a 2000 Exp Eddie Bauer. Mach stereo with 6 disc changer, steering wheel controls, rear audio controls, cd/tape HU, stock amp and sub. HU display went blank so I put in an aftermarket Sony. I want to hook up my stock amp and sub.

Here is the Sony harness connected:

Here is the amp/sub:

 

[rgalka]

Hmmm... well I only know my 1994 Eddie Bauer set up.. and the HU feeds the stock amp... and the stock amp feeds the stock sub amp.... so the stock set up (on the 1994) doesn't use the sub pre amp outs for the signal.. I assume that it is generating them interally in the main amp.

So in the rear panel do you have 2 seperate amps? In you photos I am only see the one which looks similar to my stock subamp, but I only have 3 wires going in. Where is you main stock amp? Or does the 2000 explorer hu use an integraed amp with sub pre amp outs? The thing with the sub amp is that it only needs one channel. on my pioneer that has left and right sub amp outs the pioneer tech said that they are identical so you only need to use one.

bob

 

[The Star Thief]

Unless there's another one hiding somewhere that's the only amp I got. Again, I'm no expert, but I imagine that the power and the signal were coming from the head unit to the amp at the back and the amp at the back powered the sub.

 

[rgalka]

Ok..that's what I thought... So then the Ford HU should have sub pre amp outputs going to the subamp... So if you can determine which wires the ford hu sub outs connected to then that is where your sony sub pre amp should connect to.

Have you tried your new sony HU without the sub outs? If so does everything work except the sub woofer?

bob

 

[The Star Thief]

Oh yeah. Stereo works great just no sub.

So should I trace the lines back from the sub and see which is which or should I run wire from the Sony to the amp and splice into it at the back end.

Thanks for all the help, BTW. I really dig this forum

 

[rgalka]

Well from looking at you photos i would guess that the right most cable harness sticking out of your dash is the one that has the wires that go to the sub. On the sub amp the thick green and black is probably the 12v constant to power the amp, and of course one has to be the ground. The rest should match the wires on that right most harness in your dash... you need 3... one is the amp turn on and the other two would be the signal plus and minus. So do you see three wires with the same colors at the amp and at that right most harness in the dash?

 

[The Star Thief]

Yep, I see 'em. OK, so we're getting closer.

So does that mean that the thick green/black wire is already giving it power? So what next?

 

[rgalka]

what are the chances that you are handy with a volt/ohm meter?

 

[justin146]

Yep, I see 'em. OK, so we're getting closer.

So does that mean that the thick green/black wire is already giving it power? So what next?

You need the correct wiring harness- there is one that plugs into one of the unused connectors behind the radio that gives you an RCA jack. Mine didnt have an RCA, but I just spliced one on. This is all you need to make the sub work.

This is what I did:

I did this mod today. The aftermarked wiring harness i have had an adapter with 4 leads for the sub plug, but the pins were in the wrong place. I pulled the pins out and moved them down where they should be, and wired an RCA to the adapter plug.Basically, I made an adapter just like Crutchfields. I hooked the 12v to switched power instead of constant power though- then it just plugged right in. Since I sold the stock sub driver, I had to buy an aftermarket sub. I got a Swiss Audio 8" sub from my local dealer. Its mounting depth was a little too deep, but I drilled out the rear bolt hole(now a voice coil vent hole) and used some rubber tape around the sub hole as a spacer.

It sounds 1000x better even running full range (my HU has no sub out). It sounds so much better mainly because I still have the stock component speakers in the front doors- they put out zero bass.

 

[The Star Thief]

what are the chances that you are handy with a volt/ohm meter?

I would be fine with one if I had one

 

[The Star Thief]

Success!!!

Made all the connections right at the dash. Hooked the remote amp wire from the stereo to the green/violet wire at the (4) wire harness. Spliced an RCA and connected the positive to the red/black wire and negative to the brown/orange wire. Plugged the RCA into the back of the Sony and...PRESTO!!! BASS!!!

Thanks to everyone who gave a suggestion and helped me along. You guys are the best. Big thanks to the creators of this forum.

 

[rgalka]

So now you know what stereo shops not to do business with ;O)

bob

 

[The Star Thief]

Indeed.
Now I have to do the same to my Honda

 

[beachn974door]

I just bought a '01 Sport Trac that has the subwoofer and amp from the factory. However somewhere along the line someone swapped the fatory stereo for one that is not wired for the amp and sub. Any ideas as to how to wire in the amp an sub harness and make it work off of this radio?

 

[Scratch77]

use a 1.5k ohm resistor in line with the remote turn on going to the factory amp and the pop goes away.. the resistor is dirt cheap at radio shack.

 

[fusseli]

not sure if it's come up in this thread or not yet. there's a simple alternative to $25 at crutchfield or wiring it by hand.

$4 wiring harness add-on