Date: Sun, 27 Jan 2013 17:12:32 -0500
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Blinking Temp LED and Falling Fuel Gauge
In-Reply-To: <001b01cdfcaf$fa342490$ee9c6db0$@salicos.com>
Content-Type: text/plain; charset="iso-8859-1"; format=flowed
Hi Tom -
At 12:01 PM 1/27/2013, Mister Tom wrote:
>Both problems come and go.
>My question is whether this is the typical symptom for the electrolytic cap
>on the instrument cluster going bad.
If it varies with humidity then it's completely
typical; otherwise maybe/maybe not. During one
of the spells while it's misbehaving, check for
+10 V +/- 0.5 V between ground pin on the
thermostat (the skinny one) and whichever of the
other two gives the higher reading. If bad, you
have a bad panel regulator or a contact problem
on the panel. Then remove the level controller
module from the relay panel. If the misbehavior
continues (and +10 V is good) then it's
definitely inside the gauge. If not it's either
the controller itself or more likely an
intermittent open in the wiring to the sender.
>2) The fuel gauge needle will drop slowly, from an accurate reading, all the
>way down to the reserve mark.
>
>I watched it fall from a little over half to the reserve mark in about ½
>hour while driving.
If the temp gauge is dropping at the same time,
then it's the panel regulator or its
connections. If the temp gauge is steady then you can eliminate the regulator.
It sounds like a flaky connection that's
gradually increasing resistance when live. Or
conceivably a heater short inside the
gauge. There is only a heater inside the fuel
gauge, no electronics. If you drop the rear of
the tank an inch or so you can get your hand far
enough in to unplug and replug the sender in case
that connector is flaky. Also cycle the B and E
connectors on the back of the fuse/relay panel,
and the instrument panel connector.
>The fuel level is indicated correctly after turning the ignition off and on
>again.
I can't explain that, if you meant that just
cycling the ignition cures it temporarily. There
aren't any electronics to reset except the
regulator itself - and if it were giving a
problem you'd see it on the temp gauge as
well. This could make it a real stinker to find.
This would be a good time to have a spare panel
to swap in (or spare fuel gauge ditto) to
eliminate the gauge as a possibility.
The wiring goes from panel connector pin 7 to B3
on the back of the fuse/relay panel; then back
out through E5 and straight to the sender. With
the panel unplugged you should see about 35 ohms
to ground with the tank near full, and about 170
when you've just hit the reserve.
You could break the panel supply lead (black, pin
8) and insert an ammeter, then let it sit while
the gauge goes through its cycle. If the current
rises as the gauge falls it's a short in the
gauge; if it drops it's a resistive connection in the wiring.
Yours,
David
