[TR] Fwd: TR250 Issues

[Randall]

> The TR250'S ignition idiot 
> light likes  to shine.  No apparent reason, the original 
> Lucas alternator should be  in good shape.  Part substitution 
> of the external voltage regulator has no  effect?
> I am stumped, time for a frame off restoration, huh?

No, just a little electrical troubleshooting.  I would probably start by
pulling the connector off of the voltage regulator, and also the
brown/yellow (NY) wire off the alternator, then turn the key on and see if
the light comes on.  If so, there is a short to ground somewhere in the NY
wire.

If not, then reconnect the wires, start the engine, and check the voltage on
the NY wire (wherever it's easy to reach, probably at the regulator).  If
you find 12v on the NY wire and the light is on, then there is a wiring
problem between the light and the ignition switch.

If you don't find 12v on the NY wire, then there is a problem either in the
alternator, or between the alternator and where you checked for 12v.  

BTW, I believe it's effectively the alternator that controls the light,
rather than the regulator.  However the regulator has to pass current from
the light into the alternator, to start it working, so it does control the
light indirectly.

Randall