turn signal circuitry

I received the turn signals yesterday from Old Brits for my '72 Commando (what great folks to work with.. there was a mis-shipment on their part, when I called, they immediately acknowledged the error and had the correct parts in the mail within the hour!).

I got my front signals hooked up to the OEM wiring.. all the colors jived with the schematic. Haven't received my flasher unit yet, so I just jumpered the flasher connections under the seat. I would have expected the appropriate turn signal to light continuously with the turn switch movement, but no dice on either left or right. Definitely getting power at the flasher connection.

I'm just trying to noodle out the logic behind the wiring for the turn signal indicator light in the nacelle. It has one wire coming from the LH signal feed, and the other from the RH signal. Unless this is a dual element bulb, I don't see how the second wire circuit (to the indicator) would provide a complete loop. Does this bulb have to be operational for any of the turn signals to work?

Illuminate me please!

Phil
Austin

pauldridge said:

I'm just trying to noodle out the logic behind the wiring for the turn signal indicator light in the nacelle. It has one wire coming from the LH signal feed, and the other from the RH signal. Unless this is a dual element bulb, I don't see how the second wire circuit (to the indicator) would provide a complete loop.

Click to expand...

As you have discovered, the warning bulb is wired between flasher circuits, so it does not have a direct ground.

When the right side flashers operate, the left side circuit becomes the ground for the warning bulb, and when the left flashers operate, the right side flasher circuit is the warning bulb ground, so the polarity across the warning bulb changes according to which side is flashing. As the warning bulb is only 2w, there isn't enough current flowing to the ground side circuit to light the second pair of flasher bulbs.

pauldridge said:

Does this bulb have to be operational for any of the turn signals to work?

Click to expand...

No.