problem with dimmer, gauges

hey guys, wondering if any one can help me with a problem. The firebird i have had a different radio in it when i bought it and for the longest time i went without gauge lights. I got the wire diagram and connected the grey and brown wires in the radio compartment and they work now, but i can't control the brightness with the dimmer switch. Is there another wire that goes with them. if anyone can help i would appreciate it.

It would help to know what year and model (T/A, Formy, etc.) we're talking about.

it is a 89' formula. thanks

There is a remote dimmer module mounted in the center of the dash behind the radio pedestal. Remove the lower bolster trim, swing down the convenience center, and you can see the module:

http://72.19.213.157/files/Dimmer.jpg

Jumpering the wiring has likely shunted the transistor in the dimmer module, causing constant full lamp intensity.

http://72.19.213.157/files/1986ExteriorLampsTransAm.jpg