Previous to this I had the phone clipped onto an aluminum bracket (made from a yardstick) that's clipped onto the horn pad. I was using a phone charger in the cig lighter. This worked good on the highway but city driving making turns the cord would wrap around the steering wheel- a PITA.
I recently discovered that there is 12V + and ground at the steering wheel for the horn and relocated the charger to inside the steering wheel and made a different mount for the phone (on the side instead of in the center of the steering wheell)
With the steering wheel straight ahead, the bottom of the 2 spades is +12V, the top spade is ground and goes to the metal bracket that you push on to activate the horn. I soldered wires to the charger and the terminals and taped them up with electrical tape so they don't short out.
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