[wilf leek]

John - it is a voltage stabiliser, not a relay.

It's job is to ensure that instruments like your fuel guage get a constant voltage supply unaffected by the normal fluctuations seen in an automotive electrical system.

I believe it should output around 10 volts. Obviously yours is dead.

I can't help with a supplier in the USA, although I would have thought that any decent auto-electrician should know what it is. You could also try an instrument supplier - these things are commonplace.

If you get really stuck, email me and I could get one here in the UK, but I think you should be able to source one more locally than that!