I have an 88GT Convertible with a 3g alternator. I have had strange
voltmeter gauge problems with it ever since I got it.
When I originally got the car it had a stock 2g alternator in it and the
gauge behaved the same way as it does now. The needle will hang around
halfway on the gauge (which I assume is correct). When I turn accessories
on the gauge drops slightly. When I turn my turn signals on it drops/goes
back up synchronously with the blinker. With all my accessories on it use
to drop into the red zone So I installed a 3g alternator along with 2 gauge
wiring. The gauge doesn't drop as dramatically as it use to but it still
does a little. I've asked a couple other guys with fox's and 3g's and they
tell me their gauge is rock solid with their 3g alternator.
I tested the battery with my voltmeter at idle with all my accessories on
and I get 14.2V. The gauge in the car sure as hell doesn't reflect that!
It is hard to read the stock gauge inside the car but I want to say it is
showing somewhere between 9-10v with all the accessories on.
Ideas / Suggestions?
Sounds like its within normal ranges, to me. Is there some specific
electrical problem that would make you think there's a problem?
Gauges are funny things... The true test is that the car starts, accessories
run effeciently and your lights stay bright regardless of the rpm level. If
all these check out ok, don't go looking for problems that probably don't
No real electrical problems making me suspect something. Just the strange
gauge behavior. One thing though, I was under the impression my lights
would not dim when the rest of the system is under load. When I roll both
my windows up at the same time at idle the headlights dim a little.
SOunds more or less normal to me. I've had cars with "no problems"
that would dim like that and others with "no problems" where that
didn't happen. It may depend on how the cars wiring is arranged, the
actual output voltage of the alternator, the condition of the battery,
etc. All could be within normal specs but on the low side and allow
it to dim a little bit.
'88 LX 5.0 (now in car heaven)
'89 LX 5.0 vert
'99 GT 35th Anniversery Edition - Silver
Mods to date - Relocated trunk release to drivers side, shortened throttle cable.
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