I recently purchased an '06 Mustang. When I turn on the headlights, they flash bright quickly, then quickly dim to almost nothing, then slowly get bright again. This process takes about three seconds. I have never had a car that did this, and am wondering if this is normal, or perhaps the headlights had been changed by the previous owner? They look like the stock light housings.
Thanks for any help you can offer.

 

HIDs do this.

 

Confirming my hids do this.
If you follow wires you'll most likely find ballast attached to the wires.
(metal boxes that allow hids to fire up)

 

Thank you for the replies. I did find the ballasts you described attached to the wires.
Thanks again guys.

 

Make sure the headlights are aimed properly. To high and you constantly blind other drivers. Hids are very bright compared to halogens

 

Hmmm. I noticed that after I installed aftermarket smoked headlights & HIDs (to compensate for smoked lenses) on my 04' that they seem to be aimed to low. I dont see a way to aim them. Am I missing something or is it "factory aim only"?
sorry for hijack