help with the illumination wire on alpine xda-100

[ilikesound]

i was helping my friend install one of those alpine ipod+usb head units tonite, and came across something strange. He has a VW jetta, 2005, i think, and the harness he bought didn't have any sort of colors for the illumination, and the ignition. we double checked with the local shops and the piece he picked up is in fact the correct model of harness for his ride (so they say)i ended up getting it to work through trial and error, but the thing is, the head unit will turn on when the ignition isn't engaged, thus draining the battery. you have to manually turn it on and off. kind of a bummer. i'm wondering if it's continually draining the battery, even when "turned off". anyone have experience with VW's?
thanks

[exalted512]

So you have the constant tied to the ignition? Yes, that will drain the battery, even if you push the power off.
-Cody

[tk421]

almost all cars withh have separate CONSTANT POSTITIVE, and ignition wires to the head unit.

to find it.. turn car off.. use multimeter... ground the -ve lead to car chassis... poke around all wires until u find one that reads +12V DC. label

turn key to ACC position. repeat the poking until 12 shows up... label as ignition.

illumination. keep key on ACC... turn park light switch on... poke around... 12 v.. u know what to do!

[ilikesound]

it's the strangest thing, though. this harness had the following:

2 purple wires (for neg or pos speakers i assume.)
2 Green wires (also for neg or pos speakers i also assume)
2 white wires (have no idea, but multi'd them, nothing.)
one faded yellow (was the 12v)
one black (obviously ground)

and that's all. seriously. i've honestly never seen one like it. so if it doesn't have an ignition, where....does that wire go?
again, thanks for the speedy replies. haha. man..cody, have you ever seen that kind of harness? i still think it's the wrong one, but how to be sure if they tell you that you're wrong?

[Greg Peters]

FWIW, I did an install in an '04 Jetta and even using the correct harness, I had to run my own switched power wire and tap into something on the headlight/parking light circuit (dash lights) to connect to the illumination wire so the dimmer function would work to darken the HU's display when headlights were on.

[exalted512]

There is no ignition power on those Jetta's, its done through a bus system (a data wire essentially).

You will have to run a wire over to the ignition harness or something else that comes on/off they the key. You also have no illumination wire, that will have to to the parking light wire.
-Cody

[pentavolvo]

x2 thats how it has to be done

[ilikesound]

oh ok, i thought i was going insane for a minute there. thanks for the replies guys, you really saved me.:)