>
> Apparently this circuit involves some pulse or frequency magic for the
> later gauges that try to keep the gauge working instead of just pegging
> it.

The controller operates by dropping a low resistance to ground (30Ω or so)
on the gauge sender lead, simulating an overheated sender.  The ones
supplied with 2.1l do this in brief pulses that will trigger the blinker
without moving the needle much.

Yrs,
d