Ignition light

[Terry S Martin]

I have recently purchase a 1969 XKE Roadster. I have Robert Bentley Manual with an electrical circuit diagram for the series 2.
It shows 4 wires on the alternator, mine has only one, the other 3 have been capped and stowed.

I have no ignition light, I checked the local light wires, there is 12 volts from the fuse but no ground thru the wire to the ignition warning light unit (3 AW)
With the single wire alternator how does the ground (marked earth) activate if the wires from the alternator are capped.

If anybody could help on this I would be eternally grateful, don’t get you hopes up on the eternal thing, I am 71.and can’t remember what I did yesterday.
Thanks,
Terry

[Pex]

From memory, please correct me if I'm wrong.
I replaced my alternator with a "modern" one, having only one wire.
In my case the Alternator's wire go from alternator(-) thru the ignition light bulb to +12V (fuse) , when engine isn't running the light bulb gets earth (-) true the generator itself.

To avoid that a broken ignition light bulb prevent loading of the battery, a high ohm resistor is put parallel to the bulb.
You should have 12V+ at wire connection when the ignition is on but engine doesn't run.

[Terry S Martin]

I finally solved this issue by purchasing a 4 wire alternator from Raeelectric. Works fine.
I uncapped the stowed wiring and reconnected them. It took a little thinking about but is not rocket science.
The 3AW was toast, so I replaced it with a simple 6 volt relay, It cost me $9.00 plus $7.00 for a base adapter.
I had t add a ground but hat was easily done though the old mounting bolt.
Alternator cost about $150.. with shipping.
Purists will not like the relay but is not much different to the replacement for the 3AW that XKS sell.