74 Westfalia Electrical Gremlin Nightmare - SOLVED!!!

[dr8track]

I have some bbizarre electricaal issues and I'm hoping someone can shed some light.
New Rear Lights - Last summer I got new structures to hold all the rear tail lights. After a lot of help from the forum I got everything working properly. Brake lights reverse lights, brake lights, side marker, blinkers, everything worked great.

I recently noticed that my reverse lights were on all the time when the headlights are on. Also, the amber lights only light when turn signal is on. (Maybe thats the only time they should work?)
Brake lights work fine.

Tried new backup switch - Didn't solve the problem.

Then I noticed a new issue. If you estart the bus, then turn the headlights on, then turn the key off but leave the lights on, the engine remains running.
To kill the electric fuel pum[ and the engine you need to turn the headlights off. Sometimes when you shut off the ignition the horn also goes off.

To troubleshoot I undid anything new added since the lights originally worked properly.

Unhooked the terminals under bus to new horn I installed. Engine still runs if turned off when headlights are on.

Took out new led headlights and put the old headlights back in. - no change. Problem persists.

Disconnected power going from fuel pump to relay that was added. Connected fuel pump directly to coil. Problem persists.

So nothing that has been added is the cause, but what would cause the headlight switch to controll power to the fuel pump?

I'm baffled.
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1974 Westfalia Deluxe Campmobiles - Lake Stevens, WA

[Wildthings]

Bazaar electrical problems are often caused by bad grounds, though I an not sure that is what is going on here or not. Maybe a coin has fallen onto the fuse box and is shorting several circuits together?

[telford dorr]

Or a major harness short between the ignition circuit and the tail lamp circuit. Pull the appropriate fuses and see if any of them stop the engine issue
_________________
'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)

[KentABQ]

[Abscate]

It’s as simple as some circuit is feeding 12 volts to the primary side of the coil when it shouldn’t. That’s all it takes to keep the engine running

The late Bus (1971 on, I think) started feeding the headlights form the ignition side, so guess what?

Your headlights are backfeeding 12 volts to the coil

Get the wiring diagram , tear out what is in there, and rewire to the diagram

That will take 1/3 the time of trying to sort out someone else’s diarrhea
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.ssS!

[dr8track]

[Abscate]

One likely scenario

Someone decided they wanted the ability to turn the headlights on with the key off. They thus wired to a terminal 15 wire to the headlight switch with out removing the terminal 30 wire to same. Have a look at your headlight switch fir extra wires that don’t look stock.
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.ssS!

[dr8track]

[Wildthings]

The backup light fuse is an inline fuse that lays somewhere on the left side of the engine, it is in the middle of a black wire that attaches to the 12+ side of the coil. The other end of the black wire goes to the reverse light switch on the transmission. It is a great example of German afterthought engineering.

[busdaddy]

[dr8track]

[busdaddy]

Weren't you having problems with your backup lights recently?, and confusion over what color wire a ground should be? Are you sure you don't have a marker light powering the coil via the backup light circuit?
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[dr8track]

[telford dorr]

Pull fuses 1 and 2. See if one of them stop the problem.
_________________
'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)

[dr8track]

[telford dorr]

Check the condition of the harness in the starter area and engine bay. You've got a short between the right side tail light / side marker wire and the main black engine wire. This is usually caused by a temporary short on the (unfused) main black engine wire which melted its insulation enough to fuse it to the tail light wire.

Does the tail light light when the engine is running, perchance?

Has this bus ever had an engine fire, requiring harness repair?
_________________
'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)

[dr8track]

I did a little probing around the wire harness and couldn't see any obvious issues. I was curious if I might have temporarily resolved whatever was shorting out by just moving the bundlle around. Put fuse 2 back in and no such luck, but I did discoveer a couple more things.

Transmission not in reverse, engine started, headlights on, turns on reverse lights. Turn key off, engine goes off even with headlights on. So in any gear other than R it doesn't have the problem of continuing to run if the headlights are on.

New discovery... even w/o running or key on, put it in R and the front parking lights come on along w the backup lights. With engine running and headlights on I have the same old problem.

I'm going to pull the battery out tomorrow and open up the back of the tail light housing and take a closer look.
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1974 Westfalia Deluxe Campmobiles - Lake Stevens, WA

[Abscate]

[Jrh5r]

I recently had a similar issue. Spent days trying to resolve it going through wires. Finally took off the turn signal lenses and removed one bulb at a time. The front turn signal bulb was shorting out between the two tabs, feeding power back through the harness. Try removing a bulb at a time and see if that resolves the issue.

[Wildthings]