Ok bartamos, tests conducted per instructions. But let me confirm one thing. You said, "1. test removed horn power wire"...did you mean the Load, Battery, or Switch wire, because the only one that I removed earlier in this discussion was the Switch wire, which I left disconnected as shown in the attached picture, for the below tests.
I had the mm hooked up exactly as you stated. I put the negative battery cable on the battery (the positive was already on) and got the below results. I touched the red probe to the wire and the relay terminals (one at a time), while holding the black probe on truck ground for each test.
1) 0.00 at the Switch wire (currently disconnected from the horn relay) coming from the mast jacket bearing - and there should not be any voltage coming from so can I assume that the wiring to the button/switch is good?
2) 0.00 (Load) 6.5v (Battery) 6.5v (Switch) So, there's no voltage on the 'Load' terminal that currently both horns are connected to, there's battery voltage to the 'Battery' terminal on the horn relay (coming from the voltage regulator) and there's battery voltage at the 'Switch' terminal on the horn relay (again, with the wire from the Switch disconnected.)
