Originally Posted by Kirkland Sig
Going to try to answer your questions to the best of my ability...
- Didn't use any RCA outs.
- I'm not sure how the harness runs the inputs to the amp. I did not touch the amp during the install and all I did was connect the Metra harness to the OEM harness.
- Where would I find an adaptor that converst to differential inputs?
I used that link and mirrored the pin outs on my Metra harness exactly.
- He did not use a meter and just checked that everything was connected properly...
I thought the Metra harness was the only one I needed as I saw some other posts (see below) that mentioned it was just a simple BMW harness adapter that would do the trick. I tried PMing the guys that did the install but wasn't able to get a response. I see Technic's harness but I believe that harness is just for an upgrade of the OEM Hi-Fi amp?
I'm one of the guys you PM'd, sorry didn't notice.
My car has the 8400BH and has the Hi-Fi Amp. I do however have an aftermarket amplifier that powers the underseats (upgraded to SWS) and the fronts. The rear are still powered by the HiFi amplifier and they do work. I fade mostly to the front and I haven't really listened to them with any care so I can't speak for the quality.
My upgrade path was this:
1) SWS and JL Amplifier installed with Stock Radio. I did not use Technic's harness but I did the same wiring work. I'm an electrical engineer and am quite comfortable doing this kind of thing. The JL amplifier at this point used the stock radio's level output. (IIRC)
2) I purchased and installed a Dynavin. I did not change any wiring with regards to amplifier feeds (i.e., switch to RCA)
3) Dynavin failed and I purchased the 8400BH. Again, I did not change any of the amplifier feeds but I do plan to run RCAs from the head to the JL amplifier eventually.
Considering that with the Pioneer 8400BH feeds the stock Hi-Fi amp that in turns feeds my rear speakers, I'd say that you can make it work with what you have.
The stock Hi-Fi amp has a very small gauge wire that is the remote turn-on lead. I tapped off of this to turn on my JL amplifier. I want to say this small guage wire extends to the front of the car and is in the harness where you plug in the radio. Look for it in the factory harness. See what pin it corresponds to and make sure that the Pioneer's remote turn-on lead matches to that pin. I want to say that the Metra harness did not match these up and I had to directly wire this turn-on to the Pioneer's remote turn-on lead. I can't say with 100% certainty though because I did this work Last July and again, I'm an electrical engineer that troubleshoots and develops so much it's second nature to me so I identified and solved the issue rather quickly. Enough so at least that I can't remember exact details.