Help With Electrical Gremlins

[dualbay]

Hello, I have a 72 bus which has been sitting many years; installed a new fuel sending unit and gauge was working perfectly, turn signals worked etc; then after cleaning a few wires under dash and unbolting turn signal from column everything went nuts. The fuel gauge stopped working and turn signal stopped working completely, not even noise. I did find a brown wire from the ignition that was unhooked so I grounded that - I could not find were it was supposed to go, may have been that way or I may have bumped it not sure, either way it didn't fix anything. If I turn the hazard switch on my fuel gauge now jumps with each movement.

I have gone all through the wiring, cleaned all grounds and tested with ohm meter - grounds appear all good, nothing visibly bad with wiring, fuse box all terminals cleaned and brand new fuses.

The gauge cluster is confusing as the fuel sending unit is controlled by the black and brown wire at the top of the picture - as etched in the metal it appears they are saying the black is 12V and brown ground - however; the brown wire will pulse with power too with hazards on. More confusing, is the turn signal lights which are those blue and red wires, the black wire (again listed as 12V) hooks up to the metal plate to I guess electrify it, then you would think the blue-red wire would have to ground but it also has power, so the result is the lights flash dim or not at all with the hazards on; if I take the bulb and ground it on the cluster case outside of its little island then it lights up significantly brighter when powered by its blue-red wire; however, when powering the bulb by that black wire and running a separate test ground to it - the bulb is very dim. The situation makes no sense to me as the blue-red wire runs directly to fused power #11 and the black wire runs to the turn signal relay switch - which with hazards on sends power down the black wire, so were is ground supposed to come from? Without power on the back of the cluster and those little islands for the bulbs all have proper ground.

The turn signal switch off the steering column pictured below - with the key on if I test those wires none of them have power, shouldn't one of them have power? Also, oddly enough the turn signal lever still does activate high beam on the headlights properly.

Any help or insight is really appreciated, been days spinning my wheels on this, just don't understand how so many things could go bad at once.

[Danwvw]

Yes, there needs to be power 12 volts when you turn the key on to the Black wire the dazy chain of wiring to the oil and alternator lights and turn flashers. K2,K3,K5,K5

The power comes from the top of the fuse block the next to the last fuse. Before that it's from the ignition switch 15 wire which also is the power to the ignition coil and before that it's the 30 wire back on the bottom of the fuse block where it joins the Red/Wht wire to the battery see the schematic. Looks like the metal sockets plates for the K2,K3,K5,K5 are at 12volts but the main metal on the back of the instrument cluster is the Neg. ground but not sure.

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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[dualbay]

[dualbay]

To update, those blue-red wires are whats giving power to the metal cluster area - if you remove all of those bulb sockets then the black wires have no power - seems like the lightbulb is acting like a circuit and transferring the blue-red wire power into the metal - then the metal is transferring the power to the black wires - the black wires daisy chain to the fuel gauge at the top - so when the blue-reds pulse for the hazard light it causes the fuel gauge to pulse. But it all comes from the blue-red wires. Thinking if the black wires had their own constant 12v power - then when the blue-reds pulse it wouldn't cause the fuel gauge to move since power would be constant? If this doesn't sound right to anyone just let me know, trying to understand.

[telford dorr]

[Danwvw]

"telford dorr" is correct! I will correctly refer to them as the Blu/Red wires because the wider color is said first. It sounds like, what is happening, is you don't have 12 volts on the 15 wire from the ignition switch for some reason. The 15 wire should have 12 volts when the key is on. And the Big Red 30 wire is where it gets its power, so check that its got power. See D in the schematic above.
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1960 Beetle And 1679cc DP W-100 & Dual Zeniths!

[dualbay]

[dualbay]

[telford dorr]

[dualbay]

[telford dorr]

Yup. (it's the brown 18 AWG wire from ignition switch terminal "SU" in the schematic above.)
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'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[dualbay]

[busdaddy]

[dualbay]

[dualbay]

Just received the new ignition switch and installed today fixing many issues; however, there are still a few weird things maybe you guys could help with.

The turn signals now work and function properly on the exterior; however, on the instrument cluster both turn signal lights flash at the same time - no matter if you turn on the right or left signal. That said, the right and left bulbs use the same wire (the blue/red wire in my pic), so I truly can't see how they could function independently - is this just how VW does it, both bulbs flash for a turn?

Second, my right turn signal runs very fast both on the dash and exterior lights - the left turn signal functions normal. I have brand new light fixtures and bulbs front and rear - cannot see anything wrong with either fixture. Does anyone have ideas on what could cause this?

[busdaddy]

Both arrows flash, it's the way VW did it, you are smart enough to buy a VW, you must be able to figure out which way you moved the lever, right?

The fast flash means a bulb isn't working, or one or more in that circuit are the wrong wattage.
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[dualbay]

[dualbay]

Was hoping someone could help verify my coil wiring on my 1972, the wiring diagram doesn't seem to have all the colors that are going to the coil.

The wiring harness that feeds my coil has a brown wire coming out of it that is grounded to the aluminum fan casing. I assume all solid ground wires are grounded, but can someone verify this is a ground wire to engine?

My coil negative post has only one wire from the harness - a brown/green striped wire. My coil positive post has a white wire and a black wire from the harness.

I have aftermarket carbs so I have directly run wiring for the chokes, fuel pump etc.

Also, do you guys directly ground your coil to the engine, like run a wire from the negative coil post directly to an engine ground point?

[busdaddy]

The brown wire in the coil harness to the shroud on a 72 is test network #17 (sometimes brown/white), the grey/green is #13 and the white is #15, all are redundant and better left disconnected and taped up. The Diagram above has the test network circuits (orange dots) washed out, the one below shows them more clearly.

The coil won't work if it's grounded, the only wire that has to be on #1 (-) is the green one from the points, they ground it to charge and "unground" it to fire the spark.

You aren't running your fuel pump off the coil are you?, not good for the ignition switch and possibly dangerous in a crash or fire situation, a real fuel pump control relay is a much better choice.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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[dualbay]