On this day, a couple of fails (car alarm, door locks, and horn installation)

[CmuCmu]

Here I come again with questions and a story:
My truck (BIG10 87) has never had power-anything. I was installing an alarm kit that came with door poppers, and surprise surprise, not only do these doors don't have the holes necessary for the cables (gonna redneck it and wire it as discreetly as possible through the panel so as not to drill on metal), but it didn't even have the central locking module! - Also, wasted 2 hours looking for 2 specific wires: From the switch to the starter relay (for the antitheft cut-off), and headlight positive (from headlight switch to wherever). All I have to continue are the wire colors. Gonna buy the module tomorrow, so if you could please help me out, I'll finish the installation for cut-off and headlights.
And the next part is more of a rant than anything: That truck hasn't had a working horn for a while. It has an aftermarket steering wheel with a single-wire button. So i figured, I'll wire the new horns to the original wiring instead of keep using an external wire/button. Well, I couldn't find where the single-wire ends (pulling it tells me it has a spring at the end), and the steering column doesn't even have a ground. Anyway, back to the external wire/button... set up the new horns, plugged into a new wire, routed everything properly, gonna reuse the old button... And the screws' threads went kaput.
But wait, there's more! I can but a button tomorrow, let's test whether the whole thing works.
And it didn't. Turns out part of the new wires doesn't have continuity on the positive side.
So yeah, tomorrow I'll install the module, and a new wire and button for the horns. Learned a lot though.

 

[Matt69olds]

Look at the turn signal switch connector. There will be a black wire. That’s the horn relay trigger wire. Ground it, you should hear the relay click, and hopefully the horns sound.

Headlight power coming out of the headlight switch is either yellow or light blue. Look at the headlight dimmer switch, you should see one of those colors.

There should be a purple wire coming out of the ignition switch, that’s the crank wire to the neutral safety switch.

 

[CmuCmu]

Look at the turn signal switch connector. There will be a black wire. That’s the horn relay trigger wire. Ground it, you should hear the relay click, and hopefully the horns sound.

Headlight power coming out of the headlight switch is either yellow or light blue. Look at the headlight dimmer switch, you should see one of those colors.

There should be a purple wire coming out of the ignition switch, that’s the crank wire to the neutral safety switch.

Thank you so much for this input; I managed to splice further down but I'll take this advice to clear up the spaghetti farther away from the fuse box.