Hey guys, I'm having trouble finding information, what I believe, is a grounding issue with the head unit in my SC400. Here is the back story: my SC400 headunit (not the A/C part) went bad. I may have had something to do with that, but that is another story. Bottom line, it is kapoot. Luckily I have a relative that owns an SC400 who had an extra headunit and they gave it to me. Here is the kicker though, I have a 1992 SC400 with, if I remember correctly, had a pioneer headunit and the "new" one I just installed is from a 1996 SC400, which I think is a Nakomichi (don't know if I spelled that correctly). Anyways, the old one worked fine, before I decided to mess with it and now the new one sounds like it does not have a proper ground or something.

The symptoms are the following: there is a whining sound that changes with the RPM, there is a ticking noise that changes in correlation to the RPM (when I don't have an iPod/iPhone plugged in), and then there is this random section of the volume where the sound cuts out completely. So, let me expand on that.... If I turn the volume ALL the way down I can still hear the music, but if I turn the volume up just a little bit, then the sound goes away completely. I cannot figure out what to do about this and I feel like the interface between the 96' headunits and the controls/brackets of the 92' are not fully compatible. As you can imagine, this is very annoying. Any suggestions from some sound system experts?

 

I would remove the head unit and determine which one you have first. If you interchange them that might be your problem. If they are the same i would double check your grounds and assure your two antenna ports are plunged in. If everything seems ok then i would look at the amp in the trunk. These are notorious for making things go weird or no sound. Check for for rust and water in the trunk. Very known problem in the SC.

 

I had that rpm whining noise when I messed around with the head unit on my old SC. Made sure everything was properly connected and grounded, but could never figure it out.

 

The nak and pioneer are not easily interchangeable.
You cannot just swap out the headunits, you should stick with whichever your car came with (nak or pioneer), because the amplifiers in the trunk are not the same and the wiring could be different also between the 2.
I know one has a seperate subwoofer amp on the rear deck by the sub and one it is built into the main amp (I think nak is built in), so there is at least a difference in some wiring from the amp to the speakers (which could be fixed), but I am not sure about the wiring from the headunit to the amp it could be the same or different.
so you would be looking at changing the amp and doing any necessary wiring along with it. you would be better off trading for a pioneer one of just getting a pioneer one IMO.