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Tue Feb 16, 2021 6:41 pm

Hi Folks!
Our 65 bus has a tail light issue. They both work when turned on but the passenger side turn signal and brake light does not. It's a single bulb with two filaments and the they are both good. Everything is connected ok. Anything else I can do? Thanks for your help!

Roger

Tue Feb 16, 2021 7:23 pm

Start by running grounds to the taillight buckets.

Tue Feb 16, 2021 8:30 pm

Indeed, ground wires from both taillights to the body bolting point of the battery ground cable.

Tue Feb 16, 2021 9:07 pm

If you already have a park light working back there, then your ground is probably adequate. You have an issue with the turn/brake circuit, generally the black wire. If it were mine, I'd be looking at the turn signal switch itself. Check that the connections to the black/red and black/yellow wires are hooked up under the dash. Sounds like that connection may have disconnected on the one side. The issue could also be in the switch itself, though this is less likely. Let us know what you find!
Good luck!

Tue Feb 16, 2021 9:56 pm

The round metal contact(s) in the bottom of the light socket can have issues too. That can happen even with the new reproduction tail lights; a new one that I installed this winter needs to have the bulb wiggled for the light to work. It's frustrating to see the lack of quality in some of the new products. Sometimes, just changing the bulb to a different one also will help create a better contact.

Wed Feb 17, 2021 1:52 am

I agree on most replies above. New stuff blows, grounds to the battery, old stuff becomes worn, even the newer bulbs are different from the old heavier well made bulbs. Dielectric grease has always been in the tool box for ALL current connections, :arrow: or contact Chip B above and just go LED<that cured my woes and got me up to date with the times as far as visibility & reliability is concerned. Love my LED's. My first bus in the 70's (6V) actually would get brighter when Rev'ed. I have dropped solder on those socket bucket contacts too.

Wed Feb 17, 2021 7:42 am

I am a big advocate for a test light. Test the wires for function first. I disagree with the statement that if your taillights are working then the ground it adequate. The taillight can actually ground through the brake/turn wire when it isn't hot. Of course, if that's the case, the taillight goes out when you the brake or turn is activated. Back to diagnosis though, a test light will tell you if the problem is the bucket or bulb or if it is in the brake switch or turn signal switch.

Wed Feb 17, 2021 7:57 am

Don't forget the left and right taillights are on separate fuses.

Wed Feb 17, 2021 8:33 am

Had the same issue on my 65 even after I rewired it, new turn signal switch fixed it.

Wed Feb 17, 2021 9:06 am

Lind's idea: Plan A because you know you need to do this regardless.

Okie Adam: Plan B and you'll learn the flow of how power is shared to you're two separate circuits up front- before and after the turn signal. I fully agree that if your seeing this problem when walking behind the bus it may be demonstrate a totally different issue (3-4 faint but illuminated filaments in all bulbs perhaps) when you step on the brake.

Wed Feb 17, 2021 9:12 am

Okie Adam wrote: I am a big advocate for a test light. Test the wires for function first. I disagree with the statement that if your taillights are working then the ground it adequate. The taillight can actually ground through the brake/turn wire when it isn't hot. Of course, if that's the case, the taillight goes out when you the brake or turn is activated. Back to diagnosis though, a test light will tell you if the problem is the bucket or bulb or if it is in the brake switch or turn signal switch.
Exactly.

A test light is what I use for the vast majority of my electrical issues. Taillights love to ground through the headlight switch or the brakelight switch, but not both at the same time. Half the time, the problem is solved by a fresh ground connection.

Wed Feb 17, 2021 10:50 am

VW finally did the ground wires for the TLs as stock at the factory in 1970 model year. Better late than never....