Today, after a 5:45AM start, I was a little tired. Thus, when I got home I didn't do much. I paused on the way home to pick up some AA batteries from Walmart together with a small pack of blade fuses.
As I wrote yesterday, the horn fuse had blown. For some unknown reason it had a 30A fuse. I'm sure that's not right though. I checked all the other fuses and found a 5A fuse labeled Glow Plugs that was also blown. Alas, my mini pack of fuses did not contain a 5A fuse. Something to look for tomorrow.
The other day I found a base for a 12v automotive relay. Today I found the relay, together with its own base. I soldered some leads and will fit spade connectors to them and solder them to the relay base. Then I'll encapsulate the base in epoxy glue. That should make it reasonably robust.
The new plan is to try various configurations with the relay, key switch, battery and a push button switch (or 2). I believe I can still use the key switch to unlock and lock the bus despite the odd nature of the switch. I was going to have the control buttons for the lock operable from the driver's seat but it makes more sense now to have the buttons closer to the power supply.
It was 106F inside the bus this afternoon so I didn't hang around inside it for very long. I must get the solar powered ventilation working!