The very time you can expect something to fail is *precisely* when you have
been working on it! :o) If the short was at the tach then it won't have
affected the instrument voltage stabiliser, but if it were on the output of
the stabiliser then it could have. The input to the stabiliser (green)
should be a voltage somewhere between 12.8v (ignition on engine stopped) and
14.5v (engine running). The output of the stabiliser (light-green/green)
should be switching between whatever the input voltage is and 0v, about once
per second, the rate and duty cycle will depend on the input voltage and is
what generates the 'regulated' output voltage. Make sure the stabiliser is
screwed to the firewall, this is its third electrical connection, although
if this is missing it makes the gauges read high. I'm also assuming you
have the wires connected correctly as I believe one is male and the other
female so cannot be reversed, but the input is marked 'B' (battery) and the
output 'I' (instruments). That is for the original stabiliser, modern
equivalents are probably electronic giving an output of a steady 10v or so.
Grounding the green/black at the tank and the green/blue at the temp sender
*briefly*, and only for long enough to see the needles get close to F or H,
should verify correct working. Additionally, if you have provision for a
black ground wire on the tank sender, make sure the fuel gauge reads full
scale when shorting the green/black to the black, again briefly.
PaulH.
----- Original Message -----
From: "Paul M." <rowman22001@yahoo.com>
To: <mgs@autox.team.net>
Sent: Thursday, August 05, 2004 3:25 PM
Subject: MGB gauge trouble
> I recently replaced the dashboard in my 1971 MGB.
> When I did, I changed a bunch of the functions over to
> toggle switches, so there was some minor rewiring that
> took place at the time. Now, after buttoning it all
> back up, I have some gauge problems that didn't exist
> before....
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