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Sat Jun 23, 2012 10:31 am

I have a 64 Bug with original 6 volt system. I have searched previous forums before posting this and was unable to find any answeres. Both my running lghts work fine...nice and bright. Here is the problem though:

1. When I apply my brakes the drivers side, (left), works fine, however the passenger side, (right) goes from bright to dim.

2. When I turn the turn signals on, the drivers side, (left),it works fine. When I put the turn signals on for the right, the bulb on the dash flashes fast and erratic, the bulb on the right front fender flashes fast and erratic and the one on the rear does the same, but very dim and the brake light/running light bulb flashes with it but also dim.

Here is what I've done...I've cleaned the terminals on the problem side, varified that all the wires are attached correctly and in proper spot. Made sure I have a good ground and replaced bulbs.

I would appreicate any help!

Sat Jun 23, 2012 12:57 pm

If you don't have a trunk liner, metal objects could be lying on top of the butt connector in the front turn signal wire, on the problem side. Although the plexi rectangle shields the inner part of the connectors from touching the body metal, the backs of the connectors are exposed.

For brake lights, check which fusebox terminal the brake light wire is running off, and check for interference and proper mounting. Is your whole fusebox moving around?

Your symptom of bulbs flashing too fast means there is a bad ground on that side. Are you running little toothy washers on the light housing mount nuts where they meet paint?

Your symptom of a weak right brake light only does sound like a right rear wiring issue. Check where the rt brake light wire comes across the engine compartment from the main harness on the left.

All this may be irrelevant, but I hope it is of some help.

Sat Jun 23, 2012 1:03 pm

If you don't have a trunk liner, metal objects could be lying on top of the butt connector in the front turn signal wire, on the problem side. Although the plexi rectangle shields the inner part of the connectors from touching the body metal, the backs of the connectors are exposed.

For brake lights, check which fusebox terminal the brake light wire is running off, and check for interference and proper mounting. Is your whole fusebox moving around?

All this may be irrelevant, but I hope it is of some help.

Sat Jun 23, 2012 1:41 pm

These are classic symptoms of a bad ground at your right tail light. Much like a rheostat, an increase in resistance is causing the bulbs to glow dim from low current flow potential.

The bulb holder is screwed to the tail light housing, and that assembly is grounded through it's mounting studs on the fender, and the fender is bolted to the car, so there is more than one area that can cause a resistance to build up.

If it has been painted, or the surfaces under the tail light housing is dirty, or if it mounted loosely, you won't get a good enough ground.

You can verify this by taking the tail light lens off and operate the signals. Now go back and use a jumper wire from a good clean ground and touch the other end to the metal bulb holder base. If the lights brighten and/or the turn signals slow to proper flash rate, then you know it is a ground issue. Some times the bulb holders are loose or oxidized too, so try wiggling the bulb(s) when they are activated and see if that helps.

If everything is cleaned up like new and the terminals/connections are tight, it should work like new. In the worst case, you can also add a dedicated ground wire into the tail light harness going to that side.

Mon Jun 25, 2012 10:51 am

OK, I've followed all the advice from fellow Samba helpers, and since then, I've come up with some same but new info on my problem.
1. All fuses checked and good
2. Changes out bulbs
3. Checked for fraided wires - all good
4. Grounds seem fine
As reported in my original post, drivers side, (left), works fine! Passenger side, (right), does the following,
1. Running light, (bottom bulb single filiment), lights up bright w/right one. (Ground must be good)
2. When running lights are off, and right turn signal is applied, the signal blinks, but not as bright as the left one.
3. When running lights are on and right turn signal is applied, both the turn signal bulb (signal filiment), and the tailight/brakelight, (double filiment), blink together, and dim!!!
4. Last but not least, when the brakes are applied, the right bulb comes on but dim, (not as bright as the left one).
Both left and right bulbs are correct and the same.
If there was a ground problem, why would the running lights work?? Appreciate any help..Thank You!

Mon Jun 25, 2012 1:58 pm

Electrical theory is often compared to city water pressure (volts), water flow or GPM (amps), and conduit size/outlet restriction (resistance)...
http://en.wikipedia.org/wiki/Hydraulic_analogy
A bad/poor/weak ground with excessive resistance will increase the backpressure(resistance), slow the current GPM (amps), and thus limit the pressure(volts). A bad ground is like a kink in the hose (or a restrictor in your shower head). Maybe a little water will trickle out, but it won't run two sprinklers on high like it should.

I believe you are still explaining the symptoms of a bad or weak ground that has excessive resistance. It is "good" enough to light one filament of one bulb at a time, but not two. With a poor ground and two lights operated, the current "feeds back" along the path of least resistance, in this case the other bulb filament.

Did you try and connect a good jumper wire from a known good ground (such as the engine case) to your right tail light socket with the lens removed and the lights operating? That will tell you if the ground is the main problem or not.

However, when you say the stop light is dimmer than left and tail is brighter, that symptom also sounds like it could be from the wrong filaments lighting up. Dual filament bulbs have two wattages, with the larger of the two for stop lights. I would also check to be sure the wires are connected to the tail/stop light bulb socket terminals correctly.
Also check the bulb socket terminals to see that they only contact the base of the bulbs on the correct blob of solder as the terminals can get bent, weak and at times short or touch together. They are made up of plastic, copper and rivots, and cheap aftermarket replacements are not nearly as robust as originals. You have to un-screw the holder base from the TL housing and lift them out in order to inspect them.
Also check that the sockets tabs hold the bulbs tightly and are clean and free of oxidation. Try wiggling the bulb(s) when the lights are operating to verify or rule out.