Headlights and horn not working

Had a 791xv installed a couple weeks ago on my 05 Chevy Crew Cab and now my horn and low-beams dont work. Fuses are fine, switched relays on the low/hi beams and still no luck. What should I look at?

Was it done by a shop if it was take it back let them figure it out.things worked fine before it was installed.dragon

i would find out if the install shop used a data module that may not pertain to your year of truck, sometimes the data modules that are for a different series of gm vehical can un-intentionally do things like that. other than what you said you checked, i think just checking the fuses under the hood, if you hadn't done that already.canada's cold eh.

Alarm was installed at a shop. Will probably take it tomorrow. They used a 555L (I think) and a door lock module (so the locks would work with the alarm). What "data module" are you talking about?2005 Chevy CC 2wd

remove and replace batt. cable. this will reset the cpu and sometimes correct the prob.

will do that today. but that wont fix the problem will it?2005 Chevy CC 2wd

no but could correct it until you have a chance to bring it in.

UPDATE!!! Turns out both low beam bulbs went out at the same time..its kinda weird but the lights were old. I swapped out the silvestars on my 03 when I traded it in for my 05. But I did replace them with cheapies just to make sure it isnt the alarm blowing them. If the lights hold up for 2 weeks Im gonna install new silverstars. The horn turned out to be a bad connection I guess. I took it to the dealer and they cleaned the connector and it worked. It all seemed to point to the alarm because it happened a bit after it was installed and it all happened on the same night...but I guess it was just a coincidence. Thanks for all the help!2005 Chevy CC 2wd