Thread: HU Internal Wiring Questions

Don't know if this is the right forum to be posting this in. Since it is partially HU and partially electircal engineering question. If this is wrong i apologize Mods.

I have a 2005 Scion tC which i have mounted my 7" Lilliput in the double din cutout. I was able to cut the metal mounting brackets of the stock HU, and dremel some of the excess plastic down to get it mounted behind the screen with about 1-1.5" of clearence between. Right now I am using a USA-Spec PIE type of adapter which takes 2 RCA plugs from my Inspiron 1100 Laptop's headphone port and sends the signal to the 6 CD port on the back of the HU. also on the "PIE" device i have another set of inputs which the HU virtualizes as "Track 2" on the changer (The Car computer is track 1 i change track number to change input) which runs my Sirius Starmate Replay. Stay with me this will be relative i promise

In the cutout for the double din, next to the Lilliput I have about 1" of gap which i have fashioned a "button panel" out of the back corner of an old heavy plastic PC case, painted and drilled out for buttons to the HU which is Mounted behind. My goal is to solder directly to the HU contacts where the buttons are located now and run leads buttons mounted in the button panel. (similar to what many have done for the remote momentary power on buttons on their laptops) I want to have buttons that lead to Volume Up, Volume Down, AM (only listen to the local news station there which will be preset before closing back off to the HU so there will be no need to change station) FM (again only 1 station listened to) and cd Input (Which i have to press twice to get to look at the USA Spec "PIE" adapter.) and track up and down which essentially toggle between aux 1 and aux 2. I can't seem to find a wiring diagram of the actual Scion tC/xB/xB/Toyota Martix HU to tell me what type of switches are being used and if the switch for the CD input is different since that requires 2 presses to catch the PIE adapter

The two questions i have are, Does anyone know if the switches like Vol up, Vol Down, Track up, Track Down, AM and FM are Normally Open or Normally closed? as I could see both being possibilities here.

Also does anyone know how a 2 stage button like the Disc button (one press for internal cd, 2 presses for PIE adapter are wired and if it is a special switch as opposed to a N.O. or N.C.?



I have searched the forums and googled my brains out and really try not to ask dumb questions...Those people drive me NUTS too. hence my low post count. Thanks in advance. any and all help is appreciated.