Heres my hypothesis:

1. Do the RCA mod
2. Bypass sub amp (picture below)
3. ?
4. profit

Im thinking of splicing these wires together on the sub amp harness:
1 -> 10
5 -> 9


Any thoughts/ideas before I do this?

 

I looked over the wiring and noticed that the sub amp is not getting any power at all, with or without bypassing the main amp. I just don't know how people are getting theirs to work without supplying power to the sub amp. Im thinking of completely bypassing it

 

Add another one to the casulty list.

92 SC400 stock Pioneer, did a 7120 Kenwood +Ipod+GPS to factory amp and speakers. Goddamn thing has a constant buzz that can be heard at lower volumes- it's not alternator since the damn car wasn't running.

Start the car and the whine is unbearable. I used the Metra harness as it was supposed to be wired and phono plugged the sub harness (black to center pin RCA white to RCA - )

using the ground on the metra harness didn't even supply a clean enough ground to fire up the radio. I got huge buzz, and 1st thing I did was disconnect the antenna. Deck drops dead. So, I created a new ground using a bolt by the ABS computer. Deck now turned on without RCAS or Antenna plugged so I thought we were golden.

Plugged it all in and freking noise again. Start the car and alternator whine on top of buzz.

I believe the buzz is somewhere in the factory amp. The buzz is prevalent whenever the factory amp is turned on, it's not the CD drive and it's present through IPOD or any source.

So,

1)- Metra supplied ground on harness annd therefore the factory ground wire is worthless.

2)- left As-is it doesn't seem to work as advertised. The buzz like I said, is present car not running, and it's a constant tone regardless of source or input on the radio so it can't be something inside the stereo being amplified (hard drive noise on IPOD for instance)

3)Unplugging all RCA's will eliminate all buzz, plugging in sub only did NOT buzz

I gave up, just returned the damn car to stock until I'm ready to totally remove everything and go aftermarket all the way. This is way too much Bull***** just to get IPOD. This particular car has fought me tooth and nail on ANYTHING I've done. Lower it, and I get coil rattle, numerous bodywork repair problems thanks to PO. This car is a POS to modify, sorry.

I'm not a stereo rookie, used to be an installer and MECP certified. I'm just sick and tired of everything being a pain on this car.

rjp

 

Yep, I tried everything from doing the wiring in the diagrams I posted earlier, to running wires directly to the sub; basically every combination imaginable. I give up.

Time for a new sub

 

Dropped the glovebox, backseat, removed the changer, unplugged the outputs on the factory Pioneer amp, spliced into the speaker outputs and byassed the amp.

A little over 50FT of speaker wire later, everything works as it should. Deck power sounds identical to the factory pioneer amp, literally sounds the same.

I was in a rush to get to a bday party so I left the factory amp plugged in and powered up - literally the only wires cut were the output wires to the speakers. I didn't have time to experiment to see what happens if I remove the stock amp all together. It seems that the remote on (for the sub amp and power ant controls) are all daisychained through the amp.

Behind the dash, I have the Metra wiring harness adaptor wired up as it should be except no RCA input, 4 sets of speakers going to the back of the car supplying signal to the factory speaker wiring, and a "Phono Jack" spliced into the subwoofer input leads on the car and plugged into the sub out on my HU.

Like I said, works like a champ. Literally the only thing missing is the changer I left out.

In a few months when budget permits 4x 6.5" seperates, and a freeair 10" in factory location with one hell of a multichannel amp running it all will finish this deal up.

 

Randy P

I just helped a buddy install an Alpine HU into his SC with the Metra harness. I have EXACTLY the same issue you describe. As soon as you power up the radio, there is a buzz, even when the car is not running. And then alternator whine. Pull the RCAs and it's gone.

I suspect some sort of ground loop between the HU and the factory amp. I noticed that the signal grounds and the chassis ground are connected. I'm a bit stumped. If somebody has some insight, please chime in.

 

RANDYP; I should try that method and put the sub and speaker amp back into the car. I'll try it after I get off work and post my results. Question: did you splice in power to the sub amp harness on the back of the HU?

 

The noise is because the ground reference points are so far off due to impedance differences between the inputs / outputs. Metra did a crappy job on this harness. We could probably just simply hook up the speaker + on ecah corner to the harness and it'll probably give us less problems, but I don't feel like risking damaging my deck to see if it works.

Used to work on other cars (like OEM BMW) that way.

It's not worth screwing with, bypass the amp. It's $11 in speaker wire and the quickest answer. You'll spend all day fooling with changing grounds, etc etc total waste of a day, plus you aren't risking burning up your HU outputs. The harness in the trunk is even long enough you can stand outside and cut it. Pretty sweet.

Nope, behind the dash the only harness off the original radio that is being used is the one the Metra plugs into. The other harnesses, including the dedicated sub harness are just sitting there.

I'm sure someone out there will insist removing the factory amp and running all this wire is the answer but this is the fastest, neatest and is the least amount of butchery to get it to work. I can return my car to full stock in under 30 minutes if I need to.

rjp

 

will this work 4 the 2gsmodel as well???

 

Use some ground loop isolators on the RCA plugs to get rid of the alternator whine. I had to do this.

 

Make sure you tap into the correct pins at the harness for the factory sub. I have a picture further down on the first page. The sub amp is already powered by the speaker amp from the factory. All you need to do is tap into the correct Sub in + and - wires and splice them to your hu's sub out.

 

Has anyone tried jumping the amp out totally at the amp? Instead of running all that wire, just jump the inputs and outputs together. Also has anyone tried any of the plugnplay harnesses with ground loop isolators with success? Just getting ready to swap a kenwood in my SC and trying to get as prepared as possible. Thanks.

 

I hope this is the info Ive been looking for. I also hope that the sub will work on all sources and not just the radio.