The front turn signal and and daytime running light bulbs are prone to premature failure. Our technicians tell us that these bulbs can be very difficult to replace.Google+
Car Problem Reports
Cadillac STS Failure of Front Turn Signal and DRL Bulbs
Cadillac STS Problem
Average Mileage: 59,932 mi (22,400 mi - 89,000 mi)
Visitor, 2005 Cadillac STS, 37,105 mi
Dealer initially replaced the bulb. It either went bad or something else was wrong because it stopped working within a week. Have taken it back in and they are thinking the socket is bad, not sure of the outcome yet but it's interesting to know others have had this issue.
Headlight went out and I realized it requires bumper cover removal, awesome. No easy solution yet...
Visitor, 2006 Cadillac STS, 22,400 mi
Left turn signal bulb failure
Visitor, 2005 Cadillac STS, 73,000 mi
Intermittent failure of drivers side front turn signal with fast signal indicator. Signal lamp is out when it happens, but rears are fine. No repeating indicators or causation, simply stops working at random intervals.
Visitor, 2008 Cadillac STS, 76,500 mi
replace front low beam hid bulb after premature failer
Visitor, 2005 Cadillac STS, 63,000 mi
Have had to replace both in little over a year...Lucky I can replace myself but still a pain.
Visitor, 2005 Cadillac STS, 36,253 mi
Passenger running light works sometimes but mostly not. When I use the turn signal to go Right it blinks rapidly. I can see it working in the rear but it's not actually blinking in the front. Is an intermittent problem right now. Thinking turn signal switch is going out.