2007 f150 adding steering whl controls

I have a 2007 ford f-150 xlt that did not come with steering wheel controls. I just purchased the controls from ford that replace the cruise controls on my steering wheel and give me cruise, radio, and a/c controls. I installed them today but they are not working the radio. I had to pin a wire on the backside of the clock spring and ran a wire to the back of the radio and pinned it in pin 18 of the main harness. The wire is show the correct changes in resistance when the buttons for the radio are pressed. The rest resistance of the wire is 5k ohm and the pin output of the radio without the control wire plugged in is 4.9 volts. Once the control wire is pinned in place, there is no more voltage output from the radio. I took a radio from an f-350 with steering wheel controls that was 05-06 year model and that radio worked perfect in my my truck. I tried my radio in that truck and my radio did not work with that truck. Is there a reference wire on the 07 that I am missing? I checked the harness on the f-350 and there was no refernce wire for that truck but it was an older truck than mine. I don't know if ford made a different radio for different trim levels other than the audiophile radios or am I missing a reference wire. All help is welcome and thank you for any help. Also I am a professional installer so you can be as technical as you want. -nick

odds are the radio you got is not set up with that circuit for the steering controls.89' 240sx

Rockford t8004

boston z6 comp.

eclipse 3432

polk MM 8"

Taylor owes Joe a Sandwich

thanks ween! i will try to do that tomorrow at work. gonna be a busy day but i'll try to work it in between the customers cars. once i figure this out, i am gonna look into doing the digital a/c controls. the only other pin open at the clockspring is for the a/c controls

my bad , i totally forgot about that . good thing you had a manual on hand.89' 240sx

Rockford t8004

boston z6 comp.

eclipse 3432

polk MM 8"

Taylor owes Joe a Sandwich

well, i tried the wire direct to ground in pin 19 and no luck. i want to say that it is not built into the radio, but if i put ground into the pin directly above pin 19, the radio says phone. if the radio can do phone function then it should do steering wheel controls. didn't have much time to play with it but will try some more tomorrow probably.