Andy Whiteford wrote:
> >On a recent rainy early morning commute my gauge lights started dimming
> >with each beat of the wiper, then the tach maxed out, and all was dark
> >across the dash, the pitch black interior of my 1967 Alpine Series V was
> >relieved only by my high beam indicator which was now flashing and
> >keeping time to the slap of the wiper blades. My apologies to
> >Bulwer-Lytton (sp?) of "It was a dark and stormy night" fame, but I am
> >quite at a loss as to how to even try and track this little fiend down.
> >To make it worse, if I accidentally leave the panel light switch on,
> >after a period of time, the temp and fuel gauges will drop to zero,
> >causing momentary cardiac arrest. The remainder of the electrical
> >system seems to work ok. The electrical system appears relatively in
> >good shape (or at least orginal shape) with things all nice and tidily
> >wrapped up and terribly confusing. Any suggestions would be very much
> >appreciated . . .
> >
> >Patrick Wheeler
>
> Patrick:
>
> as Dennis said, "How about a bad ground under the dash?"
>
> My first thought was that your dash lights, etc, are only earthing through
> your wiper motor!!
>
> >my gauge lights started dimming..
> 1 All the gauges illumination shares a common earth, which loops from
> instrument to instrument then
> to one connection to the dash metal. It's a black wire. You might have a
> dodgy contact or broken wire there somewhere.
>
> >then the tach maxed out,
> 2 well, on my ser III, the (mechanical) tach is only earthed through the
> same lighting earth as the rest of the guages. I'm not sure how the ser V
> tach is earthed. check it !
>
> >high beam indicator which was now flashing
> 3 its supplied from the footswitch hi-beam supply, but, again, its earthed
> directly to the gauge
> so if the gauge isn't well earthed...
>
> >temp and fuel gauges will drop to zero...
> 4 these are the two instruments supplied (green&black?) via the voltage
> regulator. check it (by substitution?), and check it's earthed well by its
> screw to the dash metalwork.
> its under the dash somewhere, don't know exactly where on a LHD ser V. it
> should look like an
> inch long, inch wide metal cylinder. There should be +12v on the
> green&black with the ignition on.
> of course, the reg won't work if it aint earthed.
>
> >with each beat of the wiper
> 5 if I remember correctly, the wiper has a constant ignition-fed supply
> and the *earth* is switched: the motor contact is normally earthed as the
> wiper sweeps most ofthe screen and if the switch is closed, the motor is
> earthed as the blades reach their parked position and off they go again.
> Check the earth wire and contact on both sides of the wiper switch.
>
> excuse any mistakes, its been a few months since I sorted my electrics, and
> I don't have a wiring diagram to hand.
>
> Anyway, I'd start by checking all you earths. clean up the contacts and the
> metal they attach to with some sandpaper. And let us all know how you get
> it sorted. good luck.
>
> Andy (Enough electrics, already. Get on with that welding, will you!)