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tatcat Samba Member
Joined: March 05, 2011 Posts: 16 Location: pcbfl
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Posted: Fri Nov 21, 2014 8:43 pm Post subject: electrics question |
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new alternator in
all good 14.5 at battery and gauge
when i turn on the lights the gas gauge needle flips over to full and the voltage gauge shows 13.
car has always done this even with old generator.
just using a two way toggle switch, up headlights, center off, down running lights.
should there be such a drop in the voltage?
would a better switch and perhaps a relay remedy the situation.
perhaps a wiring diagram for the relay?
thanx |
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jspbtown Samba Member
Joined: January 27, 2004 Posts: 5152
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Posted: Fri Nov 21, 2014 9:16 pm Post subject: |
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Sounds like a bad ground and a potentially dangerous situation. |
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bruces Samba Member
Joined: October 12, 2009 Posts: 221 Location: sudbury ontario
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Posted: Fri Nov 21, 2014 9:23 pm Post subject: |
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Is the car running or not? |
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Dale M. Samba Member
Joined: April 12, 2006 Posts: 20365 Location: Just a tiny bit west of Yosemite Valley
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Posted: Sat Nov 22, 2014 8:30 am Post subject: |
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Might be bad grounds or wire gauge is to small from battery through switch to headlights (or ground wires) ...
Dale _________________ “Fear The Government That Wants To Take Your Guns" - Thomas Jefferson.
"Kellison Sand Piper Roadster" For Street & Show.
"Joe Pody Sandrover" Buggy with 2180 for Autocross (Sold)
============================================================
All suggestions and advice are purely my own opinion. You are free to ignore them if you wish ... |
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EVfun Samba Member
Joined: April 01, 2012 Posts: 5446 Location: Seattle
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Posted: Sat Nov 22, 2014 9:31 am Post subject: |
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Speedometer is not grounded. With the lights off it finds a ground through the speedometer light bulb, to the headlight switch, to the headlights, through them to ground. When you turn the lights on that ground path is eliminated and the gas gauge voltage regulator can no longer function. This causes the gas gauge to get full voltage instead of about 5 volts, so it swings hard to full. _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
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tatcat Samba Member
Joined: March 05, 2011 Posts: 16 Location: pcbfl
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Posted: Sat Nov 22, 2014 9:47 pm Post subject: |
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EVfun wrote: |
Speedometer is not grounded. With the lights off it finds a ground through the speedometer light bulb, to the headlight switch, to the headlights, through them to ground. When you turn the lights on that ground path is eliminated and the gas gauge voltage regulator can no longer function. This causes the gas gauge to get full voltage instead of about 5 volts, so it swings hard to full. |
this is where i was going to start looking.
i'd seen a video about a gas gauge sending unit that mentioned a regulator on the speedo.
any help on the location or description of the regulator. |
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EVfun Samba Member
Joined: April 01, 2012 Posts: 5446 Location: Seattle
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Posted: Sat Nov 22, 2014 11:11 pm Post subject: |
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The gas gauge voltage regulator is a small can mounted on the back of the speedometer near the top. It is likely fine, but you will need to pick a screw on the back of the speedo (perhaps the one next to to the one holding the voltage regulator in place) to attach a ground wire. The speedo uses the dash attachment for ground in a Bug, but fiberglass doesn't offer that grounding in a Buggy. _________________
Wildthings wrote: |
As a general rule, cheap parts are the most expensive parts you can buy. |
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clonebug Samba Member
Joined: January 29, 2005 Posts: 4026 Location: NW Washington
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Posted: Sun Nov 23, 2014 9:24 am Post subject: |
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On a buggy everything needs a ground. I have my speedo grounded and I have a mechanical fuel gauge. _________________
vwracerdave wrote: |
Take a good long look in the mirror and report back on what you see. |
Paul.H wrote: |
That one line on that chart is probably better info than you can get from this place in a month |
My Megasquirt Fuel Injection Turbo Buggy Build
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http://www.shoptalkforums.com/viewtopic.php?f=3&t=127936 |
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