6v Sealed Beams; How many filaments powered for high beams?

[carlk3]

My '64 Ghia powers only one filament in each headlight on low beams, but it tries to power both filaments in the headlights on high beams. On high, the low circuit is only getting four volts or so (measured at the fuses). Should it just be one filament or the other in each light? Or are they all lit up for high beams?

I'm wondering if my (probably original) headlight dipper (dimmer) floor switch is shot. Or, maybe I've wired something wrong somewhere along the line?

[runamoc]

Check it with a VOM

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Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires

[carlk3]

I've been probing all over the place with my voltmeter.

Just to confuse things, I was running a set of these LED headlights:
SMD European Headlights 6V/12V 1 Pair fits Porsche 356, 912, Early 911,
The feedback on the low beam circuit went away when I removed those. I'm now thinking that those headlights might be designed to power both "filaments" on high beams, but my electrical system can't handle the current.

To get back to some kind of known state, I put the old incandescent sealed beams back in.

Here's what I'm seeing for volts:

At battery terminals: 6.04 lights off, 5.88 high beams

The following are referenced to ground near the fuse block, flasher:

On high beams:
Red at headlight switch: 5.25
White-black at headlight switch: 5.18

Fuse block:
Low beams: 4.75
High: 4.40

At bulb:
High: 4.20
Low: 4.57

I would readily believe that the electronics on the LED headlights could malfunction when the voltage is down in the low 4s.

It looks like I'm getting a big drop through the dipper switch; ~0.78v.

I've ordered a new dipper switch and a new transmission ground strap. The original ground strap looks fine, visually, but I'm losing volts somewhere. My wiring harness was new about 15 years ago, and it is a 6v harness (heavier guage than 12v, I think).

I guess I could consider herbie1200's suggestion to "put a 6-8mm wire [wire gauge 1 or 2?] directly from battery to the trunk and use it to feed a couple of 6V relais [relays] for headlights". I found this thread: Please check lighting relay plan

Or, maybe I'd have better luck with something like this:
Vintage Car LEDs ; VC6v – 7 INCH LED HEADLIGHT KIT

EDIT: From the instruction sheets that came with the wiring harness, it is a WK-143-6165, Wiring Harness Kit, 1961-65 Karmann Ghia Sedan and Convertible. It is available from several vendors. Supposed to replicate the original.

[carlk3]

I put in the new dipper switch.
Measuring at the headlight terminals:
high beams: 4.39
low beams: 4.66

Then I put in the new trans. ground strap, taking time to clean everything I could with a rotary wire brush and some brake cleaner. Again at the headlight terminals:
high 4.44
low 4.73

I wasn't measuring in the exact same place as I was last time (as far as the ground connection), so there could be some error in comparison.

Looks like there was some improvement; around 6% on high beams. Not huge. I'm still losing about 1.5v (high beams) or 1.25v (low beams) between the battery terminals and the headlight terminals. Could this be as good as it gets? It didn't occur to me until I was done that I don't know the wattage of these replacement Sylvania incandescent sealed beams. (Do 6v sealed beams come in different wattages, or are they all the same?) Not sure I know any easy way to check unless there are some markings on the bulbs.

Where else should I look? I've already (recently) rebuilt and soldered the fuse block and headlight switch.

[iowegian]

I had headlight problems on my 6 volt '66 Beetle that gave me fits.
The problem turned out to be the terminal end of the heavy wire feeding the headlight switch (although it looked fine) that checked out okay with no load.
Resolved towards the end of the third page of the thread.
https://www.thesamba.com/vw/forum/viewtopic.php?t=754541&highlight=

[carlk3]

[iowegian]

In my case the resistance was at the "supply" end of the wire. That is, the spade terminal at the voltage regulator (regulator mounted atop the generator).
You might run a jumper directly from the positive battery post to the light switch
to see if that helps.

[carlk3]

I spent a whole day working on this, trying to do a really thorough job this time.

I clamped a long wire to the negative terminal of the battery for the COM probe of my voltmeter, and probed the whole path from battery to headlight terminal. (There is probably some voltage drop over the long wire, but it should be essentially the same for every measurement.) Conditions: engine off, high beams on. I figured that would give me the most stable reference, but there is the downside that the battery voltage slowly drops over time.

Here is a link to the spreadsheet that I used to record the results:
https://docs.google.com/spreadsheets/d/e/2PACX-1vS...FZ/pubhtml

There was an "Ah-ha!" moment when I was probing around the starter solenoid terminal 30. I stuck the point of my meter probe through the insulation on the big red wire to the headlight switch, and measured 5.55v compared to 5.95v on the stud. In the process, I grabbed the wire, and it was noticeably warm near the end. I also found a pretty big drop (0.31v) between the dipper (dimmer) switch terminal 56a and the fuse block. At around this point in my testing, I accidentally created a momentary short, and suddenly all the voltages jumped up by 1/4v or so. That's a problem with bad connections: they tend to be intermittent.

I cut the terminal off the big red #30 wire at the starter, and pried it apart. Oddly, there was no smoking gun. No heavy corrosion, or anything else noticeable to me. I didn't have a correct ring terminal to replace that one, so I decided to clean it up and solder it back on. (I also put some shrink wrap over it while I was at it.) That went so well that I decided to just solder the crimp connections on the wires to the dipper switch and on the fuse block ends of the 56a and 56b wires, without removing the terminals.

Then I went back and did the whole series of measurements again. (See the "After" tab of the spreadsheet.) There was definitely an improvement. Before, I had a 1.27v (22%) net drop from battery to headlight, although that was after the sparking incident, so it was probably worse before that (maybe 1.5v, but who knows, maybe even worse sometimes). After soldering, the drop is now 1.0v (17%). I went for a dark, icy test drive, and it looks like my problems are solved!

[iowegian]

Good news
(like I said----electricity scares me)

[carlk3]

Yesterday, I soldered a few more connections. It occurred to me that the other end of the long red #30 wire might be somewhat responsible for the 0.38v drop I see at the headlight switch terminal 30. (In theory, I think the drop should be about 0.2v for the wire itself.) But, I didn't have time to measure the results.

I'm starting to suspect that my aftermarket WK-143-6165 wiring harness might be at end of life after ~15 years.

[iowegian]

[carlk3]

[iowegian]

[herbie1200]

[carlk3]