Date:         Thu, 28 Mar 1996 09:32:00 -0800 (PST)
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         "Maher, Steve (SD-MS)" <SMAHER@gi.com>
Subject:      Oops, I "fixed" the alternator light


Finally took apart the instrument cluster on the '80 V6anagon, to find
out why the gas gauge never rose above the 1/2 mark even when the tank
was full and wouldn't take any more. "Voltage Stabilizer" was OK,
showing 9.95 volts, and sender resistance showed 54.9 ohms (I guess)
when the tank was full, which Bentley and a helpful poster on this list
said was correct.

But voltage at the + terminal of the gauge itself, showed only 7 volts
or so, even when the stabiliser was putting out its 9.95. Probably a
bad connection? So I soldered a wire directly to the output lead of the
stabiliser (Voltage regulator IC to us hardware hackers), and ran it
to the + terminal of the gauge.

Then the gague indicated 3/4 full when the tank was full-- an improvement,
anyway. Possible another bad connection from the other terminal of the
gauge, to the wire to the sender?

Doing this one right, would require connecting a wire to the sender wire,
and routing it directly to the terminal on the gauge. But I, in my wisdom,
decided to simply wire the + side of the gauge directly to 12V (13.8 when
the engine's running) instead, so I moved the soldered wire to the input
side of the stabiliser. Also cut the foil lead running from the output of
the stabiliser, to the terminal on the gauge. Bentley says that the fuel
gauge, is the only thing that the output of the stabiliser is connected
to. Hope they're right.

Now the gauge reads full when the tank is full. I do wonder what it will
read when the tank approaches empty. I'm carrying a gas can just in case.
I intend to re-wire this, correctly, soon.


But... here's the real reason I'm making this post.

When I opened up the instrument cluster, I found some amazing "innovative"
engineering, evidently done by the PO. One of the copper traces in the
flexible circuit assembly that joins the gauges, had little bubbles all
along its length, where it eveidently got a leetle warm. At one point,
the circuit was torn and evidently melted, where a bolt or something that
holds the speedo together, was now missing. Stubby, thick wires had been
soldered on, I think, and covered with black plastic electrical tape. I
gently removed the tape, and the stubbies came off with it. Hmmm. In
additin, the entire instrument cluster has several broken-off mounting
tabs, the housings of both the speedo and the clock are badly cracked,
and the whole thing looks like it's been slam-dunked by Shaq a few times.

One of the destroyed foils was for the voltage stabiliser to the gas
gauge (Ah ha!), and the other was for the alternator warning light, which
has always worked up till now. I cleaned up the connections and re-soldered
them as best I could-- turns out the copper foil is fairly thick, for a
printed-circuit. The gas gauge now works beautifully (well, considering
how I'm overpowering it with unadulterated 12V, that's no surprise)... but
now the alternator light never lights-- even when the engine is stopped
with the ignition on, and when the engine is first started but the 
alternator
isn't alternating yet-- as this car has always done in the past.

The really disquieting news is, the system voltage now never rises above
about 11.8 volts, even when the engine has been revved plenty high enough
to energize the alternator field. In the past, after starting, the voltage
would still sit at 11.5 or so, until the engine was revved past 3000 rpm.
Then the voltage would rise to around 13.8, and the alternator light would
go out.

Now, no light, no 13.8, and the car seems to be running purely on the
battery.

My question (finally!) is: Does the lead from the light to the alternator,
play an active part in the energizing of the alternator field? Meaning,
if I interrupt this circuit, do I disable the alternator? Or, is the light
seperate from the charging-circuit part of the alternator, and I've done
something else to destroy the entire alternator?

I know, this isn't a VW alternator, it's whatever was in the '81 Citation
the engine came out of. I don't know how similar the two alternators are
electrically. Any auto-electric gurus out there, who might know?

aTdHvAaNnKcSe,

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 Steve Maher   smaher@gi.com       '80 V6anagon w/Chevy 2800
                                   '66 Mustang Coupevertible, for sale

 Check out the cars at http://www.lookup.com/homepages/76242/home.html

     *** I'm a Native American, born in Illinois. Or does ancestry
                   make a difference after all? ***
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