Ginge, as both of your relays are operated from a single switch, why did you decide to use two
SPDT relays instead of just one
DPDT relay?
If anyone was considering a similar setup, but didn't want to go to the trouble of a hidden reed switches and magnets, they could easily mount a miniature
DPDT toggle switch somewhere easily accessible
(but out of sight) instead.
Miniature DPDT Relay Miniature DPDT Toggle Switch
Regarding the above pair of 10K and 2K resistors in series on the throttle 5V feed, is the 1V supply a result of the voltage drop through both resistors as you've shown
(the same as it would through a single 12K resistor), or does it come from between the two resistors
(with the 2K going to ground) like the simple voltage divider circuit below?
Vout = 2 / (2+10) x 5V = 0.83V
Alan