Alternator problem & ?

[Huw Powell]

> When I swapped the dash on my 83 URQ, I installed the console & gauges from
> an 85 CGT. When connecting the 12v supply for the gauges I just grabbed a
> wire that showed hot with ignition on.
> I have now noticed with the cold weather that when I use the heater fan, it
> shows a discharge. The lights don't go dim, and the battery doesn't appear to
> be going down. The alternator was rebuilt about 6 months ago, and the voltage
> regulator is new.
> If I connected to the power circuit for the blower motor when I did the
> install, would that account for the reading? The blower runs fine with no
> sounds of strain or slowing.
> When started the gauge shows 13.5v. After about 2-3 minutes it drops to just
> above 12v unless the blower motor is engaged, which then shows 8-10v. I have
> a spare alternator and it behaves the same way.
> What else could cause this?

Using a harness ground for your voltage gauge that gets lifted by the
heater fan circuit (ie, they share a ground) would have the same effect,
maybe even more likely, since nothing is dimming.  IE, 12 volts is
staying 12, but 0 is getting lifted a couple of volts.

I'm not quite sure where the fan ground returns to, so take this with a
grain of salt.

Nice new fat grounds set up for a bunch of these devices might yield
pretty results.  The shifter bolt down area is a great place to run
grounds, 6 or 8 mm bolts right to the chassis are there.

All my gauges used to go wacky when I operated the cig. lighter due to
this reason.

--
Huw Powell

http://www.humanspeakers.com/

http://www.humanthoughts.org/