hood open = alternator doesn't alternate...mystery solved...

[TrollFromDownBelow]

I'll cut to the chase....yesterday I changed the oil and adjusted the valves. When I was finished, fired it up to look for any leaks. Noticed I had idiot lights on. If the hood/bonnet is open the alternator light and EGR light are on ...and testing has proved that the alternator is not charging (12.4 volts). however, if the hood/bonnet is closed, no idiot lights, and the battery reads @ 14.4 volts so the alternator is working.

I'm guessing some sort of short with license plate light...however, f anyone else has experienced this problem, would like to hear how they fixed it.
_________________
1976 Westy (aka Tripod)
2.0 liter FI solid lifters
212k miles

[aeromech]

This happened once before and I believe it turned out to be the muffler valve
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[airschooled]

Make sure your deck lid prop isn’t catching on any positive battery cables.
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com

[aeromech]

Never seen one Robbie but then again I learn something every day on the samba
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[timvw7476]

[Wildthings]

Not sure what the hairpin could snag on which would cause these particular symptoms, but the hairpin does seem to be the most likely culprit.

[TrollFromDownBelow]

Propping the hood open halfway with my oil funnel, the lights were off, and I didn't see any interference with wires or the hairpin. That's what is leading me to think it may have to do with the license plate light ....it's the only electrical wire (that I can see) that has the potential to be affected.

What's really got me scratching my head, is why the EGR light goes on as well....from my understanding, it's purely a mileage-based light triggered from the little box behind the kick panel....how would anything that happens in the engine bay affect the EGR light?
_________________
1976 Westy (aka Tripod)
2.0 liter FI solid lifters
212k miles

[SGKent]

I'd close it slowly and see at what point the voltage drops. It could be a bad VR or connection, and the shudder of the lid closing disturbs it. You can also put your meter on the battery and wiggle wires.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[KTPhil]

It's like the refrigerator light controversy. Is it really off when you close the door?

[Wildthings]

Both the charge light and the O2 counter light are tied into the blue exciter wire for the alternator. Not going to pretend that I know how the counter and O2 light are supposed to work electrically.

[KTPhil]

[cmonSTART]

At one point a few years ago I actually mounted a cheap GoPro type camera in my engine bay with some lighting to figure an issue out - turned everything on and went for a drive. I think the mount is still there.
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'78 Bus 2.0FI
de K1IGS

[Abscate]

You’ve got some nasty wiring going on and the hood closing is jarring it.

Go through the harness looking for damage or OP reprodestruction
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.ssS!

[jlrftype7]

[TrollFromDownBelow]