Replace 2005 CTS left front turn signal bulb - 2005 Cadillac CTS

KMTANNER is correct for the 2003-2007 CTS. For the 2008+ CTS, you need to remove the bumper. The bumper comes off fairly easy, but there are a 2 hidden screws. Look for the youtube video on removing the bumper. I have a 2004 and 2009 CTS. I did both.

replace the turn signal flasher very common it is underneath the driver side of dash find it by hearing and touching the clicking sound it makes when turned on

Hey I literally just today had the same problem, put a new bulb in the light was on but did not blink!!!! SUPER EASY SOLUTION, you simply have the bulb in too far. I gently pulled mine out a tiny bit and it started working fine... guarantee that's all that's happening to you!!!

A dead bulb could do it.
Try the hazard lights to determine

I replaced the front turn signal bulb on my 2004 CTS. I removed about 4? screws holding the inner fender to the outer fender, just forward of the tire. Then you reach your hand in and find the socket. Twist the socket about a quarter turn to unscrew it and remove the socket. As I recall the bulb is pulled straight out of the socket.

I just replaced front turn signal bulb. Since all of them (signal and fog lamps) are integrated with the bumper, you have to do that from beneath. First ,turn your wheels to the max right.Inside the arch you'll see that it is covered by plastic shield.You will have to remove plastic clips on the sides of that shield.There are six of them and they are clearly visible.Be careful not to brake clips.Use flat screwdriver to pull hat first,then the whole clip can be removed with fingers.Once all six clips pulled out,plastic shield will almost fall by itself - no efforts needed to detach it. That's it - you've got the access to your signal and fog lamps.

Removing the tire and blocking the front end first with jack stands makes the access much better

Remove 3 or 4 of the plastic pins holding the inner fender. They are located around the lip of the fender opening. The pins are removed by pulling the center cap of the pin straight out about an 1/8" and then wiggle and pull the whole pin out.
Pull the inner fender down and back.
Reach your arm in and grab the socket and squeeze the locking tab.
Rotate the socket counter-clockwise less than a quarter turn, and pull straight back.
Reach your other hand in and remove the bulb by pulling it straight out of the socket. It takes a 3157 bulb

Actually no you don't. Crank your steering wheel all the way to the right so yo have the maxumum clearance for your hands and arms in the front of the wheel well. Remove the plastic clips that hold the wheel well splash guard and pull it back enough to allow access to the interior of your bumper.
Replace bulbs as needed.
Yes, a jack is nice and makes it a touch easier to access, but I did this in an AutoZone parking lot during a cross country road trip.
5 mins tops to complete.

YOU HAVE A BLOWN LEFT SIGNAL BULB.REPLACE BULB.

It is fairly simple to replace the turn signals on the CTS. You do not have to remove the whole bumper, just enough to let you inside behind the lights. Turn the steering wheels one way and remove the 4 clips around the bumper with a flathead screw driver. Then do it again to the other side. You can remove the top clips to give you more wiggle room. Look under the car and remove enough of the clips to loosen the sides. At this point you can stick in your hand from the wheel well and replace the lights. Just turn and pull and re-install the new lights. Simple.