Electrical tales of woe.. evidence of interconnectedness?

[James Dwan]

Head lights are out but all other lights, signals function. Fuses good, no loose wires at the switch.
Fuel gauge has gone wonky with the needle buried to the right after I start the engine.
Rough idle, lack of vehicular acceleration and backfiring but the timing is fine.
Multiple issues or one bad actor? Dwell meeter isn't working so would rather not pull the points.
Was thinking it could be voltage regulator so I checked Mr. Bently but can't find a trouble shooting procedure. Will consult the idiot manual and search engine after a much needed beer...
This is the '77 FI Bus. Thanks for any advice as this is my daily driver.
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant

[Wildthings]

You need to check the voltages at the fuse box and at the headlight switch.

What is the voltage on the #30 circuit at the fuse box?
What is the voltage on the #15 circuit at the fuse box?
What is the voltage on the "X" circuit at the headlight switch?
What is the voltage on the #56 circuit at the headlight switch?



Below is the electrical diagram for a '79 which is essentially the same as for your model, it is just a bit easier to read and has extra info.


Double click to enlarge

[busdaddy]

[James Dwan]

I ended up setting the timing even though it wasn't far off and drove it, it seems to have helped but I should get a new dwell meter and check them. Don't like the feeler gauge method that much.

I had the ignition switch replaced 2 years ago but of course this days that doesn't mean anything.

I will check the ignition switch plug, the left turn signal was delayed by about 5 seconds and sometimes wouldn't come on until I turned the wheel to the left. I checked the plugs and they seemed tight. Also the head lights would;t come on sometimes unless I jiggled the knob before they eventually stopped working.
I will take the steering wheel off and check the ignition switch tonight. Then test the voltage if that doesn't pan out.

The fuel sending unit trouble shooting procedure in the Bentley only references a failure to reach l/l not when it goes past it so I'm stumped.
When I turn the key, the needle slowly moves to the l/l and stops right at it. When I start the engine it buries itself to the right completely.
I replaced that about 5 years ago I think.
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant

[Spike0180]

[busdaddy]

I missed the part about the fuel gauge, have a look at this: https://www.thesamba.com/vw/forum/search.php?searc..._chars=200
A buried needle will result in smoke sooner or later, best you disconnect it until you solve the issue.
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[James Dwan]

I am now very optimistic that I can avoid removing the firewall to replace the sending unit.
My speedometer was acting up so I reached around it to see if it was tight. I must have knocked off the wire for the vibrator and the head light issue is either the switch or the ignition switch. But since it was acting up for several months, I am inclined to believe it's toast. I will test it as soon as I can and report back.
Thanks guys, I appreciate it!
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant

[James Dwan]

Ok, I tested the vibrator.
I have power to fuse #11.
I have power to the terminal on the vibrator.
I have 12v at the terminal on the vibrator when the key is on.
I have 2 gauges that measure ohms and the batteries are out on both...
So I am unable to test the resistance at this time.
Seems like the sender unit is the likely culprit.
Thoughts?
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant

[James Dwan]

Ok, I tested the head light switch.

What is the voltage on the #30 circuit at the fuse box? A little over 12v
What is the voltage on the #15 circuit at the fuse box? Diagram says windshield wiper switch? That is working fine
What is the voltage on the "X" circuit at the headlight switch? Is this the empty spade connector next to the one with the red wire? If so, it reads 12v
What is the voltage on the #56 circuit at the headlight switch? About 10 1/2v

For what it's worth, I no longer have high beams. When I pull up on the lever, no click, it just goes back to original position.

Going to pull the steering wheel and look at the ignition switch connection now.
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant

[Wildthings]

[James Dwan]

You're talking about the head light test only, right?
I read that I should disconnect the coil wire to eliminate shorting the ignition circuit for the fuel gauge test. I figured I'd do both tests at the same time I had the gauge cluster off.

I have 13v at the coil.

I removed the windshield wiper/turn signal assembly and there is no click when I pull upwards to activate the high beams.
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant

[Wildthings]

Yes whenever you leave the ignition in the "on" position for any length of time you need to pull the wire going to the points off of the coil, otherwise the coil and/or points may overheat. Just remember to put it back on when you are done

Not sure on your other issues, maybe a bad ground for the wipers and corroded points for the ignition?

[James Dwan]

Problem solved!

Not sure how or why but my headlights are now working. I have witnessed many an electrical issue that is solved mysteriously by moving wires and replacing them and this was the case with the headlight switch.

I had power going to the switch but the lights just wouldn't work. I opened up the switch and sprayed it with WD-40. I discovered that by touching the red wire for the other idiot lights to the spade for the headlights, they worked. After putting all the wires back, it still works! I am glad because the headlight switch I was going to by requires the hole in the dash to be larger than it is now. Evidently the type I have is hard to find?
The hi beam issue was caused by the broken screw mount located at 8 O'clock.
I put an small nut on it to keep it tight so the hi beams are now working.

I tested the resistance on the vibrator and the needle was buried to the far right. It didn't bounce at all. The test light stayed on and didn't flash so the vibrator is bad.
Since I can't test the sending unit without it, I'll get a new one and hopefully that is the only problem.
Thanks for all the help guys. I had no idea how the fuel gauge worked before this "opportunity" popped up
_________________
DAC
TCB
'59 23 Window Deluxe
'73/'77 Westfakia
'78 SuperVert

"Many dreams come true, and some have silver linings.
I live for my dreams and a pocket full of gold. Acapulco gold!" Robert Plant