So weird issue happened with my '09 tC recently. Every morning when I head out to my car and flip on my headlights, either A) They take a little bit longer (several seconds to about 20-30 seconds) than normal to turn on, or B) They don't turn on for several minutes (even though my switch is in the "On" position) and then magically light up. However, when I park my car, and try turn my lights off, the headlights stay on, even when I turn the car off, pulled the key out of the ignition and opened the door. I've never had this happen until recently, and not sure what's really going on. The lights eventually turned off on their own. I have upgraded to HID with a kit several years back, and never really had a problem with it until now. I was thinking maybe a ballast issue when turning them on, but now I don't think it is because of the lights not wanting to turn off when I open the door with the ignition off. Any suggestions on what could be going on here?

 

what kind of HID kit do you have? 55w or 35w kit? do you have a harness for it? have you tried to see if this problem still happens when you go back to stock halogen bulbs? have you tried disconnecting the battery to see if this corrects the problem, and if so for how long till the problem came back? have you done anything electrical-wise to the car recently???

gotta give us more info

 

I would start by removing the HID kit and switching back to some stock halogen bulbs to see if the problem still occurs. If switching to stock fixes the problem then something is going on with your kit either in the ballasts or the wiring.

 

Another interesting twist to the story. Finally went off today and didn't think of it, but came out to find my car had somehow turned the lights on, even though I hadn't been in it all day. The car just turned it's headlights on on its own at some point during the day.

It's a 55w Mobile HID kit if I recall correctly. Have the harness for it, and it is connected to the driver headlight plug coming from the car. Haven't tried to connect the factory bulbs as those are down in Missouri while I'm at school in Wisconsin. Don't want to go out and spend 50 bucks on some new bulbs if I'm headed home next weekend. I'll probably also try switching ballasts too since Ive got the APT fogs with 35w digital ballasts, and see if that doesn't fix it. I'll give unplugging the battery for an hour or so and see if that helps any. It seems that the problem has only shown up in the cold weather here lately, never had a problem before. Nothing electrical done to the car lately, everything has been unmodded for over a year now.

 

its your HIDs,
the stock headlight system on the tC has an auto off function as well though, if you leave them on when you turn off the car and remove the key, they would stay on until you opened a door.

but this sounds like something is wrong with your HIDs, aftermarket kits will not last forever and with how different the power needs between the stock system and HIDs are, I see these issues often when people use them.

 

Sounds like the relay in the harness is going bad

 

Should I just get a new ballast/harness or just buy the entire kit again? It seems like it is about the same price to get a brand new kit than to just get 2 new ballasts..

 

Don't they have some kind of a warranty?

 

My money is on a bad harness too.
1. Check the fuse in the harness, switch that out and see if the problem persists.

2. if not, disconnect the harness (run the HIDs without the harness) and see if the problem persists. If it doesn't persist, then is it is the 100% relay harness issue.