how would i know if back lights were modded

i bought the tib last summer and the cruise control sometimes works ive read on here that it has something to do with the backlights but idk if they were modded it or any way to tell? The guy did put HIDs in the front so maybe he did something to the back?? I know i dont have one out cause i looked and they were working fine. Basically i just wanna get my cruise control to work every time so maybe you guys know of any other reason it may be faulty ha

thanks