To pig-back off this thread.
3 out of 4 tail (break) lights do not work, at some point they all worked. I changed the bulbs and din't work so I check if there was power going to the socket with an OM reader and there is no power going to it. Would this be a ground issue as well? If so what does the ground wire look like and what would it be attached to around the trunk area?
Also, I notice that 2 of the light sockets are pretty bad shape so I would like to change them but it does not seem to be a simple turn and twist job or is it? I tried twisting but did not budge so stopped b/c did not want to break it.
Thank you in advance for your guidance!

Car 70 cutlass supreme.

 

To pig-back off this thread.
3 out of 4 tail (break) lights do not work, at some point they all worked. I changed the bulbs and din't work so I check if there was power going to the socket with an OM reader and there is no power going to it. Would this be a ground issue as well? If so what does the ground wire look like and what would it be attached to around the trunk area?
Also, I notice that 2 of the light sockets are pretty bad shape so I would like to change them but it does not seem to be a simple turn and twist job or is it? I tried twisting but did not budge so stopped b/c did not want to break it.
Thank you in advance for your guidance!

Car 70 cutlass supreme.

 

The light sockets have a metal tab that contacts the housing for ground. The tail light housing is bolted to the body to complete the ground circuit. If you are looking for power with an ohm meter then you will ruin the meter. The ohm meter is for checking continuity with no power on the circuit. Check for power with a volt meter on a scale of about 20 volts depending on the ranges of your meter.

 

They do make reproduction taillight housings for 1970 (not for 71-72). They ground to the bumper, which then grounds to the frame. All those connections need to be tight and clean. A loose ground will either or have a weak connection or the ground current will follow the path of least resistance and that is when you see the weird electrical gremlins...…….

 

The ground issue is separate. Touch one lead of the meter to the power lead at the socket and the other lead of the meter to the vehicle chassis. With the headlight switch pulled out, you should see 12 Volts. If you do, power is getting to the socket, and now you could look for a ground problem. But if no power is getting to the socket, then it's not a ground problem. You need to find where the break in the wire is.

And, yes, if two of the sockets are in "bad shape" (but you don't say HOW they're in bad shape---rusty?) this could cause a no-voltage reading even if power is getting to the socket because the rust is preventing the test lead from making good contact with the socket wiring. If it were me, and I had rusty or otherwise damaged taillight sockets, I wouldn't be messing around with them. I'd just replace them. Even if replacing them doesn't fix the problem, you need new sockets, anyway, and replacing them will rule them out as a possible source of the problem. They're not expensive.

 

Rather than piggy-backing the same question off of multiple long-dead threads, it's in your best interest to start ONE new thread. This keeps all responses in one place, and it also avoids confusion when a reply tries to answer the SEVEN year old original question and not yours. Good luck.

 

Thanks for the feedback - I will test the using the Volt meter as suggested and post results.
I did not open a new thread b/c I been told in the past that I should use or follow existing threads in order to avoid additional threads around the same topics. From now on if the thread is ancient like the ones I found I will create new one
Thanks,

 

The bigger issue is asking the same question in two or more threads (new or old). Keeping all responses in a single thread allows bad info to be caught and corrected sooner, which gets you a better answer faster. As for resurrecting old threads, when one pops up, people start reading posts from the top, don't read the date, and end up responding to the original, ancient question instead of yours.

 

Update - I was able to get all 4 lights back to work. Here are the steps I took but could not say which one step or if the combination of all helped the matter. There are some questions below so appreciate the response.

1. Removed most if not all of the grease that was on the light bulb sockets. Why is grease added?
2. Removed some of the old electrical tape, verified all wires did not have any kinks then re-taped the wires.
3. The main wires relay had a lot of grease, is this expected? I cleaned up some of it. (Picture 1)
3. After all steps above the lights worked on the passenger side (where I had 2 bulbs in the housing), the driver side had only 1 bulb on the 2nd housing unit and it did not work until I added the bulb to the first housing unit. Does the first light housing unit need to have a bulb in order for the second to work?
4. After the steps above I noticed another type of relay (Picture 2) that connects wires from main relay (Picture 1) to lights housing. I noticed that when this relay is removed from the latch on the trunk the lights do not work. Is this the ground? Also is there a way to disconnect this relay or I would have to cut the wires on both end and add new male/female relay?
5. One final comment, one of the bulbs could not be tightly secured, no joke over 30 minutes twisting and untwisting the bulb to see if it would properly latch like the others but could not get it tight so there is a bit of wiggle, I will assume this is bad but what can I do to tighten it up?

Thanks,
Picture 1

Picture 2

 

The grease is to prevent corrosion of the terminals. These sockets are not weather sealed. When the grease was first applied, it was soft enough that the bulb would easily make contact when inserted into the socket. Unfortunately as the grease ages and hardens, it can become a problem. These cars weren't intended to last half a century. You should use fresh dielectric grease now.

The original wrap was non-adhesive black plastic tape. Regular electrical tape will degrade into an oozing, sticky mess over time.

Relay??? A relay is an active electrical device. Are you talking about the connectors in Photo 1? See my comment above about the grease.

No. The bulbs are wired in parallel, so that if one burns out, the other still works.

If you mean that connector, that's the connector. for the RH tail light. It should only have brown and green wires in it, brown for the tail light circuit and green for the RH stop/tail circuit. The ground is through the bolted joint from the light housing to the bumper.

The terminals in the bottom of the socket are spring loaded and push the two barbs on the bulb up against the stops in the socket to hold it in place. If the springs corrode and break, you lose this spring pressure. The only way to fix this is to replace the socket. Unfortunately the socket is swaged into the light housing and not easily replaced.

 

Thanks for quick response Joe.

 

Glad to hear you got it fixed... electrical Gremlins are never easy to chase down. As far as the "wiggle" of which you speak, I had the same issue with my '72 Supreme. My fix? Well, I folded up some thin cardboard and wedged it in between the side of the bulb and the socket. It's been about a year since then, and it still works like a champ 😀

 

it is those spring loaded contacts not putting enough pressure upwards on the bulb. sometimes they are just loose. I tried the cardboard tip you have and also used some thin copper tape wrapped around the bulb to snug it up. Neither are great solutions and as Joe said changing the socket is pretty tough. I seen some people change out only the spring contacts.