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Sat Oct 03, 2015 9:53 am

Can someone tell me the grounding point for the front turn signals on my '65 bug?

Is it the two screws that attach the bulb holder/reflector to the fender?

Thanks.

Sat Oct 03, 2015 11:15 am

That is correct, those mounting screws make the ground at the fender.

Sat Oct 03, 2015 1:19 pm

Then the fender is grounded to the body via the bolts that hold it on..

Sat Oct 03, 2015 1:54 pm

Thanks for the replies.

I've been checking ground connections with my multimeter.

Just to confirm, is a reading of 0.1 ohms acceptable? How about 0.2 ohms?

Thanks.

Sat Oct 03, 2015 2:00 pm

rcroane wrote: Thanks for the replies.

I've been checking ground connections with my multimeter.

Just to confirm, is a reading of 0.1 ohms acceptable? How about 0.2 ohms?

Thanks.

0.1 to 0.2 should be perfectly fine for a functioning ground.

What are you testing between though? I would say 0.1 to 0.2 would be great for a resistance test between where the light housing screws to the fender and the battery negative terminal.

Sat Oct 03, 2015 3:16 pm

Yes...I have negative lead connected to battery and I'm using the red lead at the various ground points.

Sat Oct 03, 2015 3:21 pm

Better to connect a long wire directly to the battery ground cable and touch areas you want to check for grounds with lights on.

A multi-meter setup you have does not have the volts and amperage to show up a grounding resistance problem like this.

Sat Oct 03, 2015 3:25 pm

Eric&Barb wrote: Better to connect a long wire directly to the battery ground cable and touch areas you want to check for grounds with lights on.

A multi-meter setup you have does not have the volts and amperage to show up a grounding resistance problem like this.

I agree. Rather than measure resistance, I used the volts scale (with good resolution) and measure it along the path from the battery to the end device, and note the voltage drops along the way. Then tackle the largest first.

And I also used the jumper method above and just looked at the performance of the device (brightness, wiper speed, etc).

Sat Oct 03, 2015 3:26 pm

Can you give more detail on this procedure. Connect long wire to battery ground. Lights on. Touch the long wire to ground points? What is supposed to happen if I have a good ground? Bad ground?

Thanks.

Sat Oct 03, 2015 3:30 pm

I should add that the one remaining electric problem I'm trying to solve is with my lights on, when I use the turn signal, the generator light glows (not very bright) on and off in sync with the signal. Or, the generator light glows when I press the brake (with lights on).

Sat Oct 03, 2015 3:31 pm

If you have a good ground already the light should not change when test wire is touched to suspected problem electrics. If bad ground, light will get brighter or even outright work properly.

Same long wire attached to the positive cable is good for finding voltage drops on the positive side of the wiring when you have gen light glowing. Glowing gen light suddenly goes out shows you found a voltage drop.

Sat Oct 03, 2015 8:30 pm

rcroane wrote: Can you give more detail on this procedure. Connect long wire to battery ground. Lights on. Touch the long wire to ground points? What is supposed to happen if I have a good ground? Bad ground?

Thanks.

In general, measuring the resistance of a circuit in Ohms really only tells you there is continuity in that circuit.
What that means in practice is even if a wire was broken or damaged so that only one single strand of copper remained, or a ground connection such as your parking/turn signal socket stud was there but loose or oxidized, you would still have continuity and still be able read ~0.2 Ohms resistance.
However, one single strand of wire, or a loose and oxidized connection on the power or ground side, is not going to be able to carry enough current or Amps to get the desired work or Watts out of a light bulb filament.

Think of electrical wires and connections like a garden hose and fittings.
You have good city water pressure (Voltage) behind the faucet (Switch).
You have the right diameter hose (wire or conductor), but say your car is parked with one tire on the hose creating a restriction (Resistance).
Your sprinkler is not going to get the current flow (Amps) to run the sprinkler (bulb or devise) to the desired work level (Watts).

To answer your quoted question, you can get a good idea of a power supply circuit's capacity to carry current by using a Digital Voltmeter to measure the voltage drop in the entire circuit.
Put one lead of the VOM on the power supply to that circuit, and the other lead on the end user's power terminal. That's right, power to power, not power to ground.
With the user active, or On, you now measure Voltage.
Depending on the gauge of wire, the total length of said wire, and amount of connections within the circuit, total Voltage drop should be in the 1/10th of a Volt range, as in 0.1 to 0.9 Volts.
Higher voltage readings indicate higher total resistance within the circuit, which results in less flow and thus less work done.

All that said don't think it's practical to use voltage drop to measure the light's ground side, as the bulb itself has a resistance and uses up all the Voltage in operation, so that can present an unknown figure to calculate in.

On the topic of VW front turn/park light sockets, consider all the man-made connections with potential for break downs due to looseness or oxidation that the current has to travel past back to the battery Negative:
1-The bulb's base has to be clean and shiny brass, if the bulb's base is oxidized this will limit current flow. Buff the bulbs base with fine scouring pad.
2-Bulb tangs to socket, and spring loaded by the positive terminal strip. Use a bulb socket brush to clean the sides of the socket and positive terminal strip at the bottom, then give the positive terminal strip a tweak upwards to increase it's spring tension.
3-Some sockets have the bulb holder as a separate stamping crimped to the base, the plated steel to steel connection can get oxidized and limit current flow. If yours as loose/dirty, soak in Vinegar then oil with WD-40 otherwise not much you can do here, just look for the best OG used you can find.
4-The flanged mounting stud is pressed into the base with splines, another steel to steel connection. Again, not much you can do here except clean in an acid bath.
5-The two mounting studs are held to the fender with a nuts, another steel to steel connection, and subject to looseness due to it's "bolt on" nature. Here you can make a difference. VW used a toothed star lock washer here so it would bite into clean steel for good conductivity, and that's what you should have under the nuts. Get some brand new nuts and washers (5mm) to get the most effectiveness.
6-Fender to body mounting bolts, another steel to steel connection. Brand new these surfaces were clean, shiny and a simple way to conduct low voltage electricity, but over time and a paint job or two and they can become another source of added resistance. You can improve and ensure the connection by taking one bolt out to clean and buff the areas of contact, bolt washer and body so they shine bright.
7-Body to floor pan mounting bolts, another steel to steel connection. Cumulatively, there should be many points of contact to provide enough ground capacity for all the body's electrical devises, but again taking one or two body bolts out and buffing them up will ensure good general conductivity for all the lighting and devises.
8-Battery ground cable to chassis. Again, remove bolt to clean and buff then apply an oily protectant.

On the subject of your Gen light flashing with the turn signals, that would be a low voltage from the Gen problem, and not a problem with the front lights.

Sat Oct 03, 2015 8:37 pm

61SNRF wrote:
3-Some sockets have the bulb holder as a separate stamping crimped to the base, the plated steel to steel connection can get oxidized and limit current flow. If yours as loose/dirty, soak in Vinegar then oil with WD-40 otherwise not much you can do here, just look for the best OG used you can find.

Actually one can do better, by soldering up that joint or a wire soldered across it.

Sun Oct 04, 2015 6:28 am

Wow....thanks for all the great responses. I will keep plugging away at it.

Sun Oct 04, 2015 8:44 am

A big problem in the VW wiring is loose clips in the fuse box that allow corrosion and voltage drops to occur. Soldering the internal connections of those clips will help greatly.

http://www.thesamba.com/vw/forum/viewtopic.php?t=483901&highlight=fuse+box+soldering

Wed Oct 07, 2015 2:53 pm

Wow, I was just troubleshooting this same issue to brighten up my turn signals and brakes on a 6 volt big with original wires.

Here is what I found on mine.

I checked the grounds on the front and rear signal lights and cleaned the grounds but the brightness didn't come up much.

For sure clean the fuse block contacts where the fuse is and where wires connect, that helps.

I discovered my voltage drop was occurring in the ignition. A solid 6 volts was fed in and 5.2 was coming out the black wire going to the turn signal connectors on the fuse block.
From there due to all the accessories on this circuit the voltage dropped even more and was only 4.9 at the signal lights.

I moved the brake and turn signal connection on the fuse box over to the radio connector that had a solid 6 volts (disconnected the radio) and then all the brakes and turn signals were great! Wow, what 6 volts will do! Horn works great too!
Only problem with its hack is my turn signal indicator won't work due to how that circuit works when flashing and the brakes will light with no key in the car. So not really a fix but it sure showed me my grounds were good and confirmed it was the voltage drop thru the ignition that was the issue.

I am going to test a new ignition and see if 6 volts in gives me 6 volts out, and if it does the ignition itself was my cars issue.

It was only on the black wire coming out of the ignition that goes to the fuse box where brakes and turn signals connect that I had the largest voltage drop on.

Wed Oct 07, 2015 3:19 pm

I'm sure this is a dumb question, but the ignition needs to be on to test the voltage at the black wire, correct?

Wed Oct 07, 2015 3:31 pm

rcroane wrote: I'm sure this is a dumb question, but the ignition needs to be on to test the voltage at the black wire, correct?

If you mean the one connected up to the 15/54 terminal on the ignition switch, then yes.

Wed Oct 07, 2015 3:55 pm

Yes, that's the one. In my case, voltage at 30 was 6.08 and voltage at 15/54 was 6.07.

Wed Oct 07, 2015 4:14 pm

If you can keep the drop down to about .1 of a volt in any of the wiring circuits you are doing good. Do you have 6.08 volts at the battery? How much at the coil?
Do be careful not to leave the ignition switch on for very long. If the points in the distributor are closed you can burn them up.
If you remove the small wire off the coil that goes to the points, you can keep the points from burning up, if you need more test time.
When doing tests for voltage drops helps to have a draw on that wire to have the voltage drop show up. A couple of turn signal lights in parallel connected to the black wire normally going to the coil will do the trick.