stock head unit stock speakers - quick help

[DrMcDave]

i am going to install a HU in my buddies car today. I rewired my whole car but he wants to stick w/ the stock wiring and run the stock speakers. I am fine w/ this.

I am familiar w/ the crossover setup and fader but once i get the stock headunit out is it pretty self explanatory how to wire it up. I am thinking there should be 4 sets of wires leaving the stock deck. However i recall seeing something years ago about the grounds. A few tips would be great. I have about an hour and a half until i start.

[parkerbink]

I may be wrong. I removed my stock hu in the mid 90's but I seem to recall it has a common ground for all four channels. I am sure Luke or one of the electrical gurus will chime in shortly.

[parkerbink]

Here is a writeup I found on e30tech:

http://www.e30tech.com/forum/viewtopic.php?t=14625&highlight=

The amplifer wiring harness plug has the following circuits: 4 channels of input from the head unit, 4 channels of boosted output to the speakers, switched power lead (activated by head unit), constant battery power lead, and power ground. Following are the pinouts on my car as tested and verified by me:

BETWEEN HEAD UNIT AND BOOSTER AMP

Yellow/Red - Left Front Channel
Yellow/Black - Left Rear Channel
Blue/Red - Right Front Channel
Blue/Black - Right Rear Channel
Yellow/Brown - Left Channel Ground at Amp End Only
Blue/Brown - Right Channel Ground at Amp End Only
Brown - All Channel Ground at Head End Only
(note that the all of the grounds are spliced together within the wiring harness - the system uses a common ground between the head and the amplifer)
White - 12V Switched (to turn amplifier ON when head unit ON, also runs to power antenna)

BETWEEN AMP AND SPEAKERS

Pair: Black/White and Black/Brown - Right Rear Speakers
Pair: Grey/White and Grey/Brown - Right Front Speakers
Pair: Black/Red and Black/Purple - Left Rear Speakers
Pair: Grey/Red and Grey Purple - Left Front Speakers
(note that the wires highlighted in red above all run to the crossover side of the midrange drivers, you'll want to know this to keep all your speakers in phase - make sure all of your speaker (+)s go to these wires)
(also note that the speaker circuits DO NOT use a common ground when they leave the booster amp)

[StereoInstaller1]

Hey Doc...is this an early car or late? Premium or not, amplified or not?

Here is the basic rundown: Early: split ground (NOT common) left and right split to the amp...2 channel to the fader then split ground for the 4 speaker locations basically behind the fader.

Late: 4 channel common ground to the amp, 4 channel BTL to the speakers (all seperate grounds)

Some late bodies had 2 channel decks and a fader, with the amp after the fader.

So is this cat just looking to make some kind of music in this car? What a waste of time!

Luke

[DrMcDave]

okay there were only and left and right channel coming into the headunit. Its an early model car.

At this point i have everything well sorted except the speaker wires (imagine that). When i did my car i just rewired the whole thing. His car is featuring the fader and has premuim sound.

Basically he currently has 2 shitty speakers and a diskman/ipod providing music so he wants his stock ones to play.


I have to finish figuring out wtf i am doing before i have him come back to my house to finish up. We had to stop because he had to go to work.

so essentially i just need to take the four power wires from head unit to the four speaker wires behind the amp and then just ground all four head unit grounds to the common ground behind the fader? I should really just run some new wire for him but he isn't that close of a friend.

[DrMcDave]

someone confirm what i need to do to finish this please. cough luke cough.

[FredK]

Wait, I thought if you had a fader, you don't have premium sound. I had a four speaker, fader, common ground, non amplified system in my 10/88 325i. I did not run new wire,

I clipped the common ground crimps right behind the HU. I also checked each and every wire to make sure they were not coupled in any way to each other. After removing the crimps, they are not.

The common ground crimps are protected by green silicone caps that are wrapped in black tape. Cut the crimp and liberate the grounds. Hook them up to the back of the HU by whatever termination method you're using. It shouldn't take more than 15 minutes.

http://www.e30tech.com/forum/viewtopic.php?t=32429

[DrMcDave]

Wait, I thought if you had a fader, you don't have premium sound. I had a four speaker, fader, common ground, non amplified system in my 10/88 325i. I did not run new wire,

I clipped the common ground crimps right behind the HU. I also checked each and every wire to make sure they were not coupled in any way to each other. After removing the crimps, they are not.

The common ground crimps are protected by green silicone caps that are wrapped in black tape. Cut the crimp and liberate the grounds. Hook them up to the back of the HU by whatever termination method you're using. It shouldn't take more than 15 minutes.

http://www.e30tech.com/forum/viewtopic.php?t=32429

good stuff, i dunno he has premium sound via the tweeter and a fader - no idea.

hows my old ride looking. Need an s52 i hit a deer w/ my new bmw and its taking forever to fix. its not even at the body shop yet.

[FredK]

haha it looks the same! I haven't moved it since I parked it after bringing it up from PA!

I don't need an S52 quite yet. I think I'll leave the M42 alone for a little while, before I do anything to it. :D

[thereisnoyun]

uh...

yo man... whats up....

what would possess your friend to keep the stock wires...

I dont know about everyone else, but my cabrio only had one ground.

I redid all my wires, but it just went from HU to amp and amp out... its pretty darn self explanatory when I did mine.

[DrMcDave]

this one has seperate grounds. I rewired mine. i am sure i could figure it out but he's all nervous and it annoys me so i just want to dive in and be done. the stupid fader makes it different.

[DaveSmed]

Fader and premium sound, here's what I do:

Using the wiring breakdown posted above, bypass the amp by connecting the speaker wires to the headunit wires positive for positive, channel for channel. Example: For the Right Rear, you would connect Blue/Black to Black/White.


Once all of that is done, connect the left channel ground to the Left Rear speaker wire at the amp, and the right channel ground to the Right Rear speaker wire at the amp. Now you have two pairs of wires at the dash for the rear speakers.

You will now only need to run a ground wire to each front speaker. MUCH easier than running a ground to the back of the car.

To deal with the fader, unplug it, and cut the plug off. There are the wires from the amp.

[DrMcDave]

yeah i think i am just going to cut the fader out and use the stock wiring and stock amp. If it was my car i'd do it differently. If i have to rewire it i will but i'd rather not.