Agreed. The modification does not do anything for the original problem, but it DOES cure the original design flaw. The circuits are not the same as the civilian versions. There are far too many sub circuits that are all feeding off that 30a headlamp fuse. I learned that from the sticky here while I was trying to figure out the problem on my own truck the day I bought it. No lights, turn signals or brake lights all the way home from the point of purchase. Do the modification to take a majority of the load off of that circuit and repair that 30a fuse portion of the box and you'll be well off.
Let me explain a bit of logic on this topic.
I agree that doing the headlight relay modification will eliminate a large portion of the load on this circuit, thereby resolving the "effect", but not the problem.
Think about this, the headlight circuit/load has not changed since the truck was manufactured. Therefore modifying it will not resolve the real problem.
The problem is "increased load" on the 30 amp fuse since the truck was manufactured.
In many cases the increased load may be caused by deteriorated wires or connections or any other circuit components.
In this guys case,(if removing the horn fuse does indeed relieve the "increased load" causing the heat at the weak link(blade connection and fuse element), then fixing the extra load should resolve the real problem.
There should be absolutely no load created by the horn circuit unless the horn is activated by pressing the horn button. The horn button completes ground to a relay. The relay is supplied with 12v+ that comes from the same source as the 30 amp fuse,through the horn fuse. When the horn button is held down, and the relay activates, it sends the 12v+ to the horn, through the suppressor. There is a diode connected at the relay socket between the 12v+ and the output of the relay(if it goes bad/shorts, the horn will get power constantly). This together could create a draw that may be enough(combined with the headlights on) to cause the hot 30 amp fuse.
If there is, then we have to diagnose and eliminate all faulty items in that circuit.
I'll jump ahead and suggest that both the suppressor(known to go bad over time and can short to ground by design) is likely bad.
And, the diode(known to go bad over time and cause a constant horn) is likely to be bad.
And the fact that those two combined, could create an additional draw on the headlight system(they are both supplied from the 30 amp headlight fuse circuit) that exceeds the 30 amp fuse and connections capacity.
We know the diode was used only on military trucks for electrical noise elimination.
We also know the suppressor was only used on military vehicles for the same reason.
So, we can simply eliminate those, or diagnose them to see if they are the cause of the increased load and possibly solve the real problem.
Of course, at the moment, this is all speculation. That's why I am trying to diagnose this one step at a time and find the root cause and repair or eliminate it appropriately.
Doghead is amazing!!!