[sdrevlow]

Buick installed a light module that is under your steering column. It is problematic. It provides a low output voltage sensor to the switch and then applies the proper voltage and amperage to the proper circuit. They are about 150 from GM or sometimes you can find them at the junkyard. Pull the black box that the wires from the switch lead to, disconnect the two connectors and them you can remove the circuit board from the box. You will see that one of the three circuit switches is smoked. If you go to a junkyard make sure you arent buying the same situation. Look for any shorts or draws in the system or aftermarket trailer wiring. These are usually the culprit for the problem.
Hope this is in time.