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TrollFromDownBelow Samba Member
Joined: January 04, 2005 Posts: 414 Location: Metro Detroit
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Posted: Sun Oct 17, 2021 6:26 pm Post subject: hood open = alternator doesn't alternate...mystery solved... |
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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
Last edited by TrollFromDownBelow on Mon Oct 18, 2021 5:18 pm; edited 1 time in total |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16971 Location: San Diego, California
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Posted: Sun Oct 17, 2021 7:37 pm Post subject: Re: hood open = alternator doesn't alternate... |
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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 |
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airschooled Air-Schooled
Joined: April 04, 2012 Posts: 12728 Location: on a bike ride somewhere
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Posted: Sun Oct 17, 2021 10:06 pm Post subject: Re: hood open = alternator doesn't alternate... |
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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 |
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16971 Location: San Diego, California
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Posted: Sun Oct 17, 2021 10:14 pm Post subject: Re: hood open = alternator doesn't alternate... |
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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 |
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timvw7476 Samba Member
Joined: June 03, 2013 Posts: 2206 Location: seattle
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Posted: Mon Oct 18, 2021 12:37 am Post subject: Re: hood open = alternator doesn't alternate... |
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aeromech wrote: |
Never seen one Robbie but then again I learn something every day on the samba |
He means the steel hairpin pivot on the right side of the engine door, it can snag all kinds of stuff near the battery, & if you've got creative wiring/dangling cross-harness to the LR light array.
Which I do. : l Careful now. |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50353
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Posted: Mon Oct 18, 2021 12:53 am Post subject: Re: hood open = alternator doesn't alternate... |
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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. |
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TrollFromDownBelow Samba Member
Joined: January 04, 2005 Posts: 414 Location: Metro Detroit
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Posted: Mon Oct 18, 2021 4:40 am Post subject: Re: hood open = alternator doesn't alternate... |
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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 |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Mon Oct 18, 2021 8:03 am Post subject: Re: hood open = alternator doesn't alternate... |
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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 |
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KTPhil Samba Member
Joined: April 06, 2006 Posts: 34022 Location: Conejo Valley, CA
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Posted: Mon Oct 18, 2021 8:13 am Post subject: Re: hood open = alternator doesn't alternate... |
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It's like the refrigerator light controversy. Is it really off when you close the door? |
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Wildthings Samba Member
Joined: March 13, 2005 Posts: 50353
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Posted: Mon Oct 18, 2021 9:36 am Post subject: Re: hood open = alternator doesn't alternate... |
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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. |
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KTPhil Samba Member
Joined: April 06, 2006 Posts: 34022 Location: Conejo Valley, CA
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Posted: Mon Oct 18, 2021 10:30 am Post subject: Re: hood open = alternator doesn't alternate... |
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Wildthings wrote: |
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. |
Stick your cell phone and a flashlight inside and close the lid. Record the video and see what's happening. |
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cmonSTART Samba Member
Joined: July 15, 2014 Posts: 1915 Location: NH
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Posted: Mon Oct 18, 2021 10:32 am Post subject: Re: hood open = alternator doesn't alternate... |
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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. _________________ '78 Bus 2.0FI
de K1IGS |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22670 Location: NYC/Upstate/ROW
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Posted: Mon Oct 18, 2021 10:41 am Post subject: Re: hood open = alternator doesn't alternate... |
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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 _________________ .ssS! |
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jlrftype7 Samba Member
Joined: July 24, 2018 Posts: 3582 Location: Chicago
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Posted: Mon Oct 18, 2021 11:14 am Post subject: Re: hood open = alternator doesn't alternate... |
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KTPhil wrote: |
It's like the refrigerator light controversy. Is it really off when you close the door? |
LOL.... _________________ '68 Westy- my first VW and vehicle/Bus- long gone.- sold it to a traveling Swiss couple....
'67 Type 3 Fastback, my 2nd car- gone
'69 Semi-Auto Stick Shift Beetle-gone
2017 MINI Coopers, our current DDs
‘84 Tin Top - Hilga....Auto |
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TrollFromDownBelow Samba Member
Joined: January 04, 2005 Posts: 414 Location: Metro Detroit
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Posted: Mon Oct 18, 2021 5:23 pm Post subject: Re: hood open = alternator doesn't alternate... |
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airschooled wrote: |
Make sure your deck lid prop isn’t catching on any positive battery cables.
Robbie |
Robbie wins the prize...or at least 50%. It was the hatch 'holder upper'. THe alternator wires had got caught behind it, and it had chaffed through the insulation. Took all of 30 seconds with my wife sitting in the bus letting me know when the lights went on and off.
A bit of electrical tape to cover up the bare wire, and a zip tie to pull it out of the way, and we are good to go. _________________ 1976 Westy (aka Tripod)
2.0 liter FI solid lifters
212k miles |
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