Help with iPod2Car on 2003 sierra denali

[lotionontheskin]

Hello, i just recieved my ipod2car kit with harness K (PXHGM3) (GM-C). after installing it, i can hear my ipod but i cant go to the next or previous track using neither the steering controls nor the ones on the radio (i can turn up and down the volume though). It also doesn't charge. I have the latest firmware (just downloaded from apple today and installed it), so that's not it. also there's something that conserns me, my type of harness (according to the instructions) should have both a yellow 12v+ cable and a black ground cable. but mine only has the yellow one, this could be the problem but i am not shure. also i have a multimeter to meassure the voltage but sadly it has a lot of options and i dont really dont know how to read it. so i just kinda put the yellow cable on a random place (sorta). but even though it's a "random" place the ipod plays, so maybe it happens to be 12+ volts. If it is the cable placement, then could someone tell me how to properly read the multimeter and on what setting to put it? i know it's either AC or DC (probably DC?) when i put it on 10 dc the little hand meter went past 10 so i assumed it was 12+ but i dont know. also, if my harness needs a ground can anyone tell me if i can just solder a cable in? if so where (as in, next to what cable on the harness)?

thanks in advance~!

Oh i almost forgot. ive tried the old dip switch settings and the new revised ones (there is a green sticker that says to turn dip 2 off on my harness)

[lotionontheskin]

i was just checking the truck manual and it's actually a 2004 sierra denali (got it as a gift and i dont know anything about cars) but it doesnt matter because it's the same harness

UPDATE: i found new dip switch settings on their website, and now i can change songs on my steering wheel. but the ipod still doesnt charge. If you are wondering what where the dip switches:

1st setting found in manual: off on on off off off off on
2nd setting found in sticker that corrected previous one but still didnt work: off off on off off off off on
3rd setting that works and i found online: on off on off off off off on

these are for GMC trucks that use harness K


UPDATE 2: I found this while looking for the harness to see if it does or doesnt have a ground:

http://images.cardomain.net/products/per/PERPXHGM3_1.jpg

though mine has less cables than that one, that one doesnt have a ground cable either. so that just leaves me with one thing. the yellow cable isnt on a 12v+ source. and i have no idea how to use my multimeter. the thing is the cable is so short there arent many options... anyone know how i need to set up my multimeter to test for 12V+ spots? mines analog, the settings are:

DCV
subsettings
10
250
500

ACV
subsettings
10
250
500

DCA
subsettings
500u
10m
250m

OHM
subsettings
x10
x100
x1k

UPDATE 3: found the 12v source!! ipod now charges !! now i have to put everything back together (oi)

UPDATE 4: everythings done but the truck's battery ran COMPLETELY dry, it doesnt even close the door lock. also im pretty ####ed that i scratched the air conditioner controls. but i put a lil magic marker in there and you can hardly see it.

UPDATE 5: PICS! (taken with laptop webcam so sorry for quality)

charging when radio is turned off:
http://img.photobucket.com/albums/v694/niu-niu/IMG00011.jpg

when radio is turned on:
http://img.photobucket.com/albums/v694/niu-niu/IMG00012.jpg