| Crusing in the Passing Lane Joined: Jun 2011 Posts: 5,096 | No longer need voltage regulator. Did you record what came and went to the horn relay when you took it apart? Horn relay should have a signal wire from the horn button that would be small. Plus voltage from source and output to the horn itself should be larger wires. If the wires were cut, the remainder held in the wire crimps should give you a clue as to color and gauge. Red is normally used for source. A wire diagram from any similar age GM truck should apply.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
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