Nice day out so doing deferred maintenance.
Horns haven't worked since got the truck (89 2.0L) and it may be a simple fix. I found the connector on the back of the horn snapped off, but no loose wire, and what looks like a green or blue wire crammed under one of the ground wires. Am i correct in assuming that is actually the hot wire and needs to be connected to that connector instead?

Wire in question is burned and heavily corroded, so i'll have to replace it a bit further back until i can test.

 

Yes, horns are grounded thru their metal case
Use a jumper wire from Battery positive to the connector on horn, to see if horn works

1989 should use a Horn relay, so the steering wheel button is a Ground, it grounds the horn relay which closes it and powers up that wire at the horn

 

Yea horn still works. Need to track this relay down and see if its getting power. i had the sterring wheel apart to see if there was corrosion or loose wires, looked fine. hopefully its just this one wire thats the problem.

 

Any idea what these go to? I don't think these are related to the horn, but figured i'd check. Had a weak ground anyway so this while cable needs refreshed.
One plug was melted, came out of the wiring harness near the horn and they all look unprofessional, not sure if they're factory.

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That's the Battery's 0 volt side, the ground for the 12volt side, wiring

Larger cable to block may have corroded so the starter motor(65amps) and alternator(80amps) may have used the smaller wires which WILL melt them

DC Electricity travels in a loop, from one pole of the battery to the other
So for the 12v side to pass 60amps the 0 volts side must also pass 60 amps

People spend time working on the 12volt side(positive) but often ignore the 0 volt side(negative)


Vehicles generally have these Grounds from battery Negative
Battery to Block, larger cable, for stater and alternator
Battery to inner fender, and Rad support, smaller wire, relays, headlights and horn
Block to frame, tail lights, fuel pump, fuel gauge(can be battery to frame as well)
Block to Firewall(usually Head to firewall) all cab electrics

 

Yea i'm def replacing the main ground. it looks pretty tore up. just trying to figure out where all the straggler cables actually go. the manual only shows 2 wires leaving the negative, one that goes to ground which i assume is the engine block and maybe a body panel, and then one line goes to some node that then goes to the "Electronic Control Assembly" into pin 60 and 40, Heated Exhaust sensor, and EEC power relay. But i have about 4 cables all dangling off this.

 

Maybe found it. pulled out the technician's shop manual. I think i see the connectors in question. it just says "To battery ground" and "To battery ground cable" on the two plugs that look like them. guess i'll need to splice in some new wires with these plugs. A pre-made replacement cable doesn't show one of the plug however. It lacks the connector midway and just has a ring connector and a plug at the terminal clamp. Rock auto has one that looks correct, but th emiddle plug is replaced by a ring connector, and the terminal end plug is replaced by a spade? Interesting.