Rt side brake light doesn't work, 54 K late special

[Jim K545]

I have a 54 late special. All of the taillights work the way they should except the right brake light. Rt taillight works and rt directional light works but the right brake light doesn't. Both filaments work as they should, taillight filament is dimmer and the directional filament is brighter. Left side lights work as they should. I have added external grounding wires to both taillights. Did the same with my old 1970 Commando.    If someone can suggest a solution before I poke around these brittle wires, I would appreciate it.

[rdgodwin1954@gmail.com]

Suggest removing the socket and lightly sanding the area where the socket rim makes contact with the socket and the socket rim itself.

[Jim K545]

Thanks. I'll give it a try.

[joefrazer]

If the tail light and the turn signal work, then the issue is not at the socket. A bad ground would cause all three to fail. There are two wires to each tail lamp. One feeds the tail light itself and the other handles the turn signal and brake light half of the bulb. It's the wire with yellow thread in it's casing. Hopefully, there's enough good wire to see the difference.

Here's a link to the 1953 wiring diagram. It is the same as your 54 except that it doesn't show the pigtail for the upper lamp.

One thing to try, remove the bulb from the upper lamp and see if your brake light now works. I've seen where the wrong bulb will cause the lower to act erratically.

https://circlekf.com/kflit/SM/kfsm700/kfsm700028.jpg

[Jim K545]

Thank you for the tip, Joe. I pulled the top right side bulb, but it made no difference. I fiddled around with the 1158 bulbs in both sockets, checking for clean contacts and solid wire connections. Still no brake light on the right side, but now I notice another issue. The top and bottom bulbs blink together like they do on the left side but when I turn on the headlights, the top and bottom right side bulbs alternate blinking. The left side bulbs still blink together. I don't know if it matters but the right side bulbs blink maybe 50% faster than the left side. I think the issue runs deep into the wiring. I am going to dive under the dash and start checking and cleaning more contacts and wires, especially the directional signal plug connector. I've been referring to the 1953 and 1954 Manhattan schematics I have. The '53 shows 1 bulb and the '54 shows 3 bulbs. I split the difference for my late Special! 

[joefrazer]

One side blinking faster than the other usually means one of the bulbs is not working. Is the front bulb working? I have a 54, however, it's apart right now so I can't check to be sure but if memory serves, the upper lamp did not blink when the turn signal was actuated. With no turn signal, if you step on the brake, does the left upper lamp get brighter or does it stay at tail lamp illumination?

[Jim K545]

Thanks joefrazer. I finally was able to get back to the garage after a bout with covid.....again. I don't know exactly how I did it, but the brake lights work now. I cleaned and applied a little dielectric grease to every wire connection I could access under the dash without disassembling any of the dash and tried the brake lights. Hoo-rah! Just a bad connection somewhere or just a coincidence? And to answer your question, both the taillight bulb and upper bulb (Safety Glow) work the same. Both blink with the directional signal and both brighten with the brakes. Thanks again for the help.

[Jim K545]

Nope. Just a coincidence. No brake light on right side. Just an intermittent problem. Dropped the bottom of the instrument panel to check wiring. Nothing looked loose or broken so I put it all back together. Now I have no brake lights on either side. Everything else is the same, just no power to the brake lights. One step forward, two steps back.

[joefrazer]

In between my last comment and now, I had the same issue occur with my 70 Dodge Coronet. I replaced the turn signal switch and everything now works as it should.