1A Auto Video Library
Our how-to videos have helped repair over 100 million vehicles

How To Replace Taillight and Bulb 04-07 Cadillac CTS

Share on:
  1. step : Removing the Taillight Assembly (0:29)
    • Remove the spare tire cover.
    • Remove the five plastic clips.
    • Remove the panel.
    • Pull the insulation back.
    • Pull the harness from the car.
    • Disconnect the harness.
    • Remove the two 10mm nuts securing the light.
    • Push the harness through and pull the taillight out.
  2. step : Replacing a Bulb (3:03)
    • Push the tab down and twist the socket counterclockwise.
    • Pull the bulb out.
    • Push the new bulb in.
    • Twist the socket clockwise to secure it.
  3. step : Replacing the Taillight Assembly (3:39)
    • Feed the harness into the car.
    • Line up the taillight and push it into place.
    • Reconnect the harness and clip it to the car.
    • Put the insulation back into place.
    • Replace the panel.
    • Replace the five plastic clips.
    • Replace the spare tire cover.

Brought to you by, your source for quality replacement parts and the best service on the Internet.

In this video we're going to show you taillight, both replacing the whole taillight if you've had one broken, as well as replacing the bulbs, if you have a bulb out. This is on a 06 CTS, same as any 03 to 07, same as the CTSV as well. The only tool you'll need is a 10mm socket with a ratchet or a wrench.

To replace a taillight or service taillight bulb the hardest part really is getting to the back of the taillight. I'm going to start by removing your spare tire cover. Pull that up out of the way. There are a few of these. You need to untwist these and they pull off. You're going to take off four of them: one there, one up here, another one up here, and another one here.

I'm going to be working on the passenger's side. I'm going to take this one off over here as well. If you're working on the driver's side, you'd want to take this one off. Fast forward as I remove those trim plugs. Once you take the four off in the back, you're going to pull this rear panel out, just put it like that. Take this one off over here. Now you can take this insulation and pull forward off that stud and back. Now you can see the back of your taillight. Right here is the connector. Take that off the body, pull back on this tab, that comes apart. There are two 10mm nuts, one there, and one up there, remove those. You have a 10mm socket with a ratchet. Once you get them started they come off pretty easy.

The last thing I want to do is I'm going to push my harness through here and my taillight comes right out. If you're looking to change these bulbs, they all have little lock tabs, press the tab down, twist counter clockwise, pull it out, the bulb pulls out, new one can push in.
Maybe you get into a little bit of an accident, at 1A Auto we sell the brand new taillight. Everything's going to go in. Everything's going to mount the same. It's going to plug in all correctly. Get your harness connection through.

To put the plug in, I'm pushing the plug through, put the lock on there and seal it correctly, and then carefully pull up on this seal here. Guide your light in, look in behind so you can see the studs go into the holes, everything goes in correctly, start tightening your nuts on here.

I want to fast forward here, as it's all pretty self-explanatory. Start both the 10mm nuts on the back, and then use your ratchet and socket, and you want to tighten them evenly, so don't tighten one up all the way and then the other one all the way. Tighten one up some, then tighten the other one some, and switch back and forth until they're nice and firm. Once it's tightened up, make sure that your harness is connected and then you can put your trim back in place, the side panels, all the buttons push on, put your rear panel in and your tire cover.

We hope this helps you out, brought to you by, your source for quality replacement parts and the best service on the Internet. Please feel free to call us at toll free 888-844-3393. We're the company that's here for you on the Internet and in person.

Tools needed for replacement:

    Ratchets & Related

  • Ratchet

  • Sockets - Metric

  • 10mm Socket

2005 - 2007  Cadillac  CTS
2004 - 2004  Cadillac  CTS
Search Videos
Go To Top

Same Day Shipping

Orders ship same day when ordered by 2pm ET. Need your part faster? Choose expedited shipping at checkout.

Guaranteed To Fit

Providing you the highest quality, direct fit replacement auto parts enforced to the strictest product standards.

USA Customer Support

Exceeding customers' expectations every day, our team of passionate auto enthusiasts are here to help.

Instructional Video Library

Thousands of how-to auto repair videos specific to year, make and model guide you step-by-step through your repair.