Thanks for the most recent post... I have no questions there. I'll get some new 1N4000 series diodes though.
I did overlook this quote last time though:
I don't see why you need another relay in your "modified" diagram. It could be done with diodes.
That relay breaks the bypass when the low beams (or passing lights) turn on so that the control block resumes control over the fogs. So, I'm
conditionally bypassing the block (when the low beams are off).
Here's why. Its hard to explain, but its really simple logic.
1) the fog lights must turn off with the high beams (on my car) to remain legal
2) the high beams do not turn on unless the low beams are already on (even if you press the high beam switch). However, the passing lights (pulling the high beam switch backwards) still work anytime.
3) the fog lights also won't turn on unless the low beams are already on (which is what I'm bypassing)
All 3 of these restrictions are handled by the same control block. So bypassing the block removes #1 and #3. I only want to remove #3 and keep #1. So bypassing the block only when the lows are off allows the high beams to still shut the fogs off because the block resumes control. When the low beams are on, I don't need the bypass because the fogs work anyway. So I only need to allow the fogs to work when the low beams are off. When the low beams are off, the high beams won't work anyway, so the fog circuit doesn't have to be broken by the highs. If the highs did work without the lows, then this design wouldn't be sufficient. See what I mean?
Then the passing lights need their own input because they work anytime (even without the low beams).
Are you saying there is a way to accomplish this without the relay? I've never heard of a way to implement a NOT-gate without a relay.
Again, thanks much for your help- much appreciated