Wiring aftermarket headunit

[cWalk3r]

I have the premium stereo from a 1990 325i vert. We figured out that in the picture below where the blue circle is that connection is bad in my stock head unit and my amp is A ok. Now on to wiring the aftermarket head unit. My wires don't match the colour of the wires on the amp bypass. So I'm just wondering if I can keep the amp in place and see the blue and green circle. Those lead to some sort of connector, on that connector there is 1 ground a purple/red wire and also 2 wires for the left front speakers 1 for left rear and 2 wires for the right front and 1 for right rear. Is it possible to take the new head unit and connect all negatives to the single ground on the factory head unit and then connect the left front to the 2 wires, the left rear to the 1. and so on for the right side? will that work connecting an aftermarket head unit?

Heres the pic mentioned:


Or should i try and follow the diy that i don't understand or just run new wires to the speakers.

and FYI i don't have a clue what I'm doing lol i have a friend that can wire car radios. I'm just trying to do some research...

[AndrewBird]

DO NOT connect the grounds together on your new HU. IT will fry it.

You need to unwrap your harness PAST the fader in the dash and find the separate pairs of wires running to the stock amp.

[cWalk3r]

Thanks that's good to know. I don't believe I have a fader but you say the separate pairs. Will these be twisted together further inside the dash and with it be a positive and negative/ground there?

And I think in having trouble understanding this because I thought our cars only had one ground wire entering the amp. So will I have to connect the amp wires together and then use the positives from the head unit connect those to the dash wires and then for negatives run new wires to the output of the amp for negatives?

Sorry for all the questions

[mattjewell]

If you unwrap that harness, you will find these:




Those green crimps are factory, pull them off!

[cWalk3r]

Thanks. I'll take a look tonight. So those will be the grounds for the negative left/right for the new head unit and I just have to figure out which one belongs to which speaker? Then then I connect the positives to the other positive wires that are in the 8 pin connector?

Would I still have to bypass the amp? Or will connecting the head unit like that cause that not to get damaged?

[mattjewell]

Thanks. I'll take a look tonight. So those will be the grounds for the negative left/right for the new head unit and I just have to figure out which one belongs to which speaker? Then then I connect the positives to the other positive wires that are in the 8 pin connector?

That's what I did with the Alpine unit I just bought. Took me a while to figure it out, but it's now working perfectly. Crisp and clear.

Now if you don't have it connected right, trust me.. You'll know. Won't sound right at all at higher volumes.

Would I still have to bypass the amp? Or will connecting the head unit like that cause that not to get damaged?

I didn't have an amp. Looked everywhere in the trunk, removed the trunk lining as well. But the new HU is amplified. I had to remove the kick panels up front and remove the speakers from the rear deck to see what color the wires coming off the speakers were before it made sense to me.

[mattjewell]

Oh and the wire nuts were not a final product, did that only to test.

[cWalk3r]

Hey thanks for the help. I found those 4 ground wires in the dash so that'll make everything easier. Just have to take a look and see which positive wires go back to the amp and then just connect them at the amp.

I dunno if anyone else has a weird problem where it comes out of the amp at one colour and by the time it gets to the speaker it's another colour. Like the rear left comes out of the amp and it's black/purple and at the speaker it's yellow black lol there must be a splice in the wires near the drivers door.

[mattjewell]

If you have a fader, that might be where they are. Since I didn't have an oem amp, I'm not sure.

Let us know if you get it working!

[cWalk3r]

I got the head unit installed and it looks great!! I'll have to take a picture tomorrow. It was actually pretty easy to install but I accidentally switched the wires for rear left at the amp and now at the head unit the positive is a yellow brown wire. I didn't have enough connectors to take it off and redo it. It all works but I think I might have either drained the battery listening to it or something in the ignition wiring is bad.

Thanks for the help, I'll update this tomorrow

[cWalk3r]