First, make sure all of the cable connections are clean and tight and the cables are in good shape, but it sounds like you blew a fusible link.
Depending on what year you have, there is at least one link.
Look at the battery side of the starter solenoid, you'll see several smaller wires connected to that terminal too. Look for a wire (wires) that has a little plastic "flag" on it. It will say "fusible link 16 ga". This, obviously, is the fusible link. Tug on the link, see if it stretches or feels soft. If yes, then it's bad and needs to be replaced. You can get replacements at the parts store. DON'T use regular wire, that would be like bypassing a fuse.
If the link is blown, you need to investigate why it blew before repairing it.
I don't have anyway to check voltage.
I removed the battery because it was easier than running extension cords to where the truck is.
The battery says 4/11 on it, but my charger showed it was in the green and fully charged.
So I have this wire from the pos post of the starter solenoid to a wiring harness (attached with a residential lug nut) is this the link?
It may have been at one time. If that is (was) the link, it looks like someone may have already done what I said not to do, replace a fusible link with a piece of wire .
What is the color of the wire that that piece was attached to? and also, what year is your truck?
It looks like someone has already done some "expert" repairs on your harness . That seems to be a common problem on these old trucks .
This is what the fusible link should look like.
fmc400 what multimeter do you recommend? Will a $20 unit work for troubleshooting the truck?
fmc400 is right, you DO need a multimeter to trouble shoot these problems.
I would say, to get by, yes a "cheap" meter will work. I prefer high quality tools but when you only use it once or twice it's hard to justify the expense.
I don't know how good you are at reading wiring diagrams, but here's a link to the factory schematics for the '74. http://www.fordification.net/tech/wiring.htm
Also, the yellow wire shows to be power to the horn relay, so that wouldn't be your problem.
One last thing, I see you're new, welcome to FTE. You'll soon learn that when it comes to electrical problems, you've got the best guy on your side.
fmc400 is the "go to" guy for troubleshooting electrical gremlins that like to inhabit our trucks.
Listen and learn.
For basic troubleshooting, any "cheapie" from most parts stores or tool shops will get the job done. I've seen analog meters as low as $10 that will work just fine. The main thing to look for when buying a multimeter for automotive work is quality, especially of the leads.
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