Coil supply, screen washers & other electrical questions

[darrenmidd]

Imagine that your charge light is some sort of voltage see-saw. If it is balanced with 12 volts on both sides, then there is no potential difference across the warning light terminals so it will not light.

With the ignition on, but the engine not running, the charge light will come on. This is because battery voltage is coming to the white ignition live wire to that side of the bulb. The other side of that bulb (the yellow wire) is connected to the D terminal of yor regulator. With the dynamo at rest, this is grounded, so the bulb lights.

When the engine is started, 12v from the battery is still being sent to the bulb on your white wire, but as the dynamo starts to generate electricity, 12 volts is also now being supplied from the dynamo to the D terminal yellow wire on the regulator. If you have 12 volts on botn sides of the bulb, there is no potential difference, so the bulb will not light.

I think I've explained that correctly, but not had a coffee yet this morning...

Thanks very much. Everything is working as it should. It was my electrical ignorance and not reading the diagram correctly that was the problem. Thanks to all who have contributed to my public auto-electrical education. I have actually learned a lot and can make sense of the wiring diagrams thanks to all the patient help. Thanks to all again.

[Wittsend]

Just to post that after careful research (manuals and car electrics books) I confirm the charge warning light connects to the "D" terminal on the voltage control box and not the "F" (field coil) terminal.
I believe our wiring diagrams to be correct.