[T3] fuel gauge and gauge light fluctuating

Jim Adney jadney at vwtype3.org
Sun Sep 21 15:10:18 PDT 2014


On 21 Sep 2014 at 12:34, David Yaghoubian wrote:

> So to start, I pulled the gauge back out and confirmed that my lamp base
> (which I was calling a harness for lack of appropriate term) does NOT have
> the #31 ground tab on the back. I think it is perhaps important to mention
> now that I installed a '71 gauge set when I did the dash in 2006 (to get the
> trip odo primarily) so I am running a 71 gauge without a #31 ground. Again,
> this hasn't been an issue up until last night (although I don't know if this
> has to do with why I can't get the gauge to seat fully)

Thanks for the clarifying that the #31 tab must have started in '69. 
Before that, the only ground was via the retaining spring clips. '71 
and  '68 gauge heads should fit exactly alike, so I don't know why 
yours doesn't want to fit all the way on. Since you seem to have 2 of 
each parts, see if you can figure out what is interfering, or if they 
are together as far as they are supposed to be.

> Right now, if I push slightly on the left rim of the gauge, the lights come
> on full in the gauge but the fuel gauge needle reads dead empty. When I
> release pressure from that edge, move the gauge a bit, or tap the dash just
> above it, the fuel needle taps out, and the lights go off completely. 

What does "taps out" mean? Full lights should mean a good ground. I 
agree that this is confusing.
 
> Regarding adding a #31 wire myself, I will go back out and take a look at
> the wires joined to the socket just below the hole where the black wire
> comes in (those would all be grounds, correct?) and see if that is something
> I think I can handle without melting anything. If not, perhaps I can
> purchase one of your extras Jim?

I'll be happy to sell you one, but you found one there. You might 
find it easier to solder in a new wire than to undo all the wires and 
get them hooked back up to the right places.

> In absence of a #31 wire for now, is there a way to definitively tell if
> this is a ground issue at the housing before getting into the soldering or
> swapping out what was a perfectly functioning lamp base?

Not at all clear. My first thought was that this was simple, but your 
symptoms seem to point to additional problems. I guess at this point 
I would suggest doing something so you have a known good ground, then 
proceed to figure out what ELSE is wrong. 

> Would adding a #31 wire eliminate the need for the gauge housing ground
> as the dash (thus making it unnecessary for me to figure out how to
> finally seat this darn thing?). 

Yes.

-- 
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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