I recently asked a question about fixing my taillight’s backup bulb sockets and got some useful information here. I got the lights generally working by messing with the spring in the existing socket and stabilizing the bulbs with toothpicks, but they still were not fully dependable. I ended up replacing the sockets. I thought it would be worth sharing the process I used. Unfortunately, I did not take any pictures along the way, but they would be tough to take in the cramped spaces. I do have a few picts showing the taillight disassembled here: https://www.flickr.com/photos/kschwarz20/albums/72157713536318558

I describe in detail how I replaced the backup sockets on my 1963 Series 62 convertible below. It took me about an hour to do the first one, and ~20 minutes to do the second one (once I knew what I was doing). I did not need to remove the taillight housing to replace the backup light socket.

 Tools needed:

- 1 long (I used a 6" one) standard slot head screwdriver

- 1 standard slot head screwdriver (a second one, can be long or regular length, but not stubby)

- #2 Phillips screwdriver

- Wire stripper

- Hammer

- A 12" (or so) test lead with an alligator clamp on one end or about a 12" length of flexible (not stiff) wire (22-gauge or similar) to use as a guide wire. String might work too.

- Heat gun (or crimping tool or electrical tape)

- Small flashlight or work light

- Magnetic tray (optional - to hold screws)

- Volt meter (only if you need to troubleshoot connectors)

- A helper (for ~10 minutes per side)

 Parts needed (one of each per side):

 Steps to replace the backup light sockets:

  1. Before you start, confirm that the backup lights work. If they don’t, you need to do steps 1-5 to see if power is getting to the existing backup light socket. If there is no power at the socket, solve that problem first. See step 20 for some ideas to troubleshoot. If none of those ideas work, check the Neutral Safety Switch (NSS) near the base of the steering column under the dashboard. You don’t need to remove any dashboard panels to access the NSS.
  2. Crawl under the car to survey the workspace to see where the backup bulb socket is located and how the wires are routed. The socket is at the bottom of the taillight housing and it is connected with a light green wire (the wire might look black due to years of dirt build up). The wire will likely run upward from the base of the socket. Once you get the lay of the land, crawl out from under the car. I used both a small AA-cell LED flashlight and LED work light with a magnetic base to see what was going on under there. I found that the LED flashlight held in my mouth aimed well for me to see what was going on while I was doing the work. It was hard for me to get a good location for the magnetic work light.
  3. Crawl out from under the car. Remove the taillight lenses using a #2 Phillips screw driver. There are two screws on the bottom of the metal cross-bar. Remove them to remove the cross-bar reflector lens and access the two screws holding in the cross-bar. Remove the cross-bar and gasket. Remove the three screws to remove the white plastic lower lens. You don’t need to remove the upper red lens, but you may choose to do so to clean it or get it out of the way (It’s just one extra screw). I put all the screws in a magnetic tray so I would not lose them.
  4. Note the position of the internal clear glass and red plastic lenses (maybe take a picture). Remove them (they slide out).
  5. Remove the old bulb.
  6. Take your long standard slotted head screwdriver and put it into the socket against the base of the socket. Tap the screwdriver handle with the hammer to knock the base of the socket off the taillight assembly. I had to give it a solid hit, more than a tap, but not a really hard blow either. If you don’t like using your screwdriver as a striking tool, you can use a long 3/8" bolt or similar here.
  7. When the socket breaks free, its retaining ring will remain on the taillight housing. Put the side edge of the long screwdriver blade along the outer edge of the ring and tap the screwdriver handle with the hammer to bend the ring inward. I did this over about 90-degrees of the ring and then I could pop it free from the housing.
  8. Take your new bulb socket and tie a loose knot in its wire about 1" below the base of the socket. The new socket should already have about 3/4" of insulation stripped off the end of its wire, but if not, strip ~3/4" of the insulation off.
  9. Use your fingers (no tools) to bend the tips of the prongs on the new socket slightly (~1/16") inward. This adjustment helps the socket fit through the housing’s hole later.
  10. Go get your helper.
  11. Crawl under the car with your light. You should see the old socket hanging from its wire. This wire is clipped to the top inside edge of the taillight housing with a small metal clip. The clip is on the inside of the housing. Reach up and push the top of the clip away from the housing and pull the wire out from the clip. You now have more wire slack and can get the old socket to a place where it is easier to work with.
  12. Cut the wire connected to the old socket off close to the socket base (I cut it ~1" from the socket base). Strip ~3/4" of insulation off the end of the wiring harness wire.
  13. Have your helper hand you the new bulb socket and long slot head screwdriver.
  14. Have your helper push one end of the guide wire (I used a 12" test lead with an alligator clip) through the hole from the outside of the taillight assembly down to you. Clip the alligator clip to or twist the wire around the metal part at the tip of the wire inside the new socket.
  15. Slowly push the socket up from below while having the helper pull it up using the guide wire/test lead. The knot you put at the base of the socket helps push the socket upward.
  16. When the socket reaches the hole in the housing, have your helper guide it through the hole while you push it through using the blade of the long screwdriver. (If you have small hands you might be able to guide and hold it in place by hand). This step is where you are glad you bent the prongs inward. This step was much easier than I expected given the tight work space.
  17. Once you have the socket fully through the housing’s hole, hold it in place from underneath with your long slotted screwdriver’s blade. Have the helper use the other slotted screwdriver’s blade to bend the outer prongs outward to secure the socket against the housing. As the helper bends the prongs, hold your long screwdriver’s blade against the socket’s retaining ring as close as possible to behind the prong being bent into place, so the socket stays tight against the housing. Once you get one prong done, you can remove the guide wire/test clip. I did the 6 o’clock position first and then worked left and right with the helper calling out clock positions as we went. I could not get my screwdriver all the way to the 12 ‘o clock position, but the other prongs were already bent and getting it to 10 or 2 o’clock was good enough to keep the socket in place when bending the last prong.
  18. Slide the heat shrink tub over either the light green wire on the wiring harness.
  19. Attach the light green wire from the wring harness to the black wire on the new socket. I used the approach shown here to connect the wires: https://www.musclecardiy.com/automotive-wiring/fundamentals-of-auto...
    You can also use crimp connectors to attach the wires or electrical tape instead of heat shrink tube to cover the wire joint. Do not tape up or heat shrink the tube yet.
  20. Crawl out from under the car. Reinstall the bulb. Test that it works by having your helper start the car, step on the brake, and put the car in reverse. If the bulb works, go to the next step. If the bulb does not work, first be sure the bulb is good. If it is, then check to see if the connector from the trunk to behind the license plate came loose (if the brake and parking lights don’t work now, the connector is probably loose, but if it is just a little loose at the bottom of the connector, the backup lights may be the only ones that don’t work). If that connector is tight and the bulb does not work, take out the bulb and have your helper carefully put the car in reverse and be sure you have ~12 volts at the center of the new socket. If you don’t, check the wire joint you made to see if there is ~12 volts there. Be smart here! In both cases, I clipped on a test lead before the car got started and tested from the side of the car because I did not want to be behind or under the car when my helper had it in reverse! If the wire joint has zero or low volts, check for voltage at the three-prong connector coming from the trunk behind the license plate. The backup lights run through the horizontal prong at the bottom of the connector. If there is no power there, you need to do more troubleshooting.
  21. Once you verify that the bulb works, crawl back under the car and use the heat gun to shrink the tube over the wire joint or wrap the joint in electrical tape.
  22. Clip the wire back into the clip at the top of the housing.
  23. Come out from under the car and reassemble the taillight lenses doing the reverse of what you did to take them apart (really!). Don’t forget to insert the internal lenses and gasket as you put things back together.
  24. Repeat this process for the other side.
  25. Thank your helper; share a cold beverage together.


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Karl, Thanks very much for the very detailed instructions and links to pictures and parts.  This is excellent information for anyone looking to replace their bulbs and have created a link to this post on our Help page under (1963) Tail Light / Backup Light Replacement Instructions by Karl S...

A great thread that will help many Trouble shoot bulb and socket replacement issues in the future 

My compliments for sharing and a job well done 
Enjoy your repaired Antique Classic Cadillac 

We are a very special breed of Car Nut to be owning these great—- Iconic Cadillacs !!




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