loss of steering wheel controls with after market radio
 

I have a 2005 Altima 3.5 SE. I just installed a Pioneer DEH-5900IB receiver last night, mainly because I was sick and tired of trying to use an FM transmitterwith my Ipod.

I knew before i installed it that I was going to lose my stereo VOLUME controls, but I did not think that I was going to lose the functionality of my TRIP button as well. When I got in the car this morning and turned everything on again, the little screen below the main odometer (where it usually displays the outdoor temp, etc.) was frozen on the "A" trip odometer, and my TRIP button would not cycle through the different computer settings as usual.

The guy at Circuit City told me that if I wanted to have my steering wheel controls back, it would cost me about $100 for some sort of adapter.

Is that true, and is there any way to get these functions back without having to pay for this adapter, etc? I really hate losing my temp, mpg, etc.