The initial choke adjustments can be made with the engine, not running. And certainly some checks, and some cleaning can be done without the engine running.
But the ultimate testing is done during and after startup.

When everything else is working as expected, the engine should start and run, even without the Brown “I” wire connected to the small terminal of the starter relay/solenoid. It’s just there for a little better insurance. For lack of a better phrase.

When test-jumping the ignition to see if there’s a problem with the key switch, you would take a wire from the battery and connect it directly to the terminal on the coil that has the red with green striped wire on it.
That would be the positive side of the coil.
you can’t leave it on very long or it can overheat the coil. But you can certainly put it on their momentarily and try to crank the starter and see if it starts.
if not, there is further testing available.

If it doesn’t start, or even act like it’s trying, go ahead and temporarily disconnect the jumper lead until you’re ready to test again.

 

oh ok, that makes sense, i had looked not long ago but i dont remember a red+green wire but i know the coil is marked for battery post

 

Yes, a 79 would use the “horseshoe“ style connector at the coil, with a red with green wire going to the positive side and a green with some kind of a stripe (white or yellow maybe?) going to the negative side. Negative coming from the ignition control module. Red coming from the ignition switch, through a resistor wire to lower the voltage.
Power from the ignition switch uses the red with green wire to power both the coil and, on a separate branch, the ICM on the fender.

 

I just cleaned the wires off and now i see it, not sure what color stripe the green wire had, the whole wire was basically black for some reason not the burnt kind of black though. now i will go test it since I've got the time.
came back to double check the colors

 

It doesn't seem that hooking the coil right up to the battery worked (as in no change from regular set up, unless i need to disconnect the horseshoe also?)… Anything else I can do while I'm out here in the slight cold?

 

Could those other tests be at least somewhat listed so i can try them in a day? maybe something that should be know is that i know pretty well nothing about electrical stuff! I'm more the mechanical type, so this thread is where any information/knowledge about electrical things would come from.
if it was a points system that would be much easier for me to figure out
i cleaned off the fuses and nothing changed for the interior.

 

Sure, but there might be so many, since we still haven't really narrowed it down much. We've thrown out ideas in your direction, but ultimately all the discovery will have to be done at your end.

1. First thing I would do, I think, is to check the carburetor for the presence of gas. Yes, I'm still leaning towards electrical, but I don't remember you confirming that you had gas at the carb.
Don't even need the engine running at this point. Just remove the air cleaner and row the throttle lever back a few times. Does gas squirt out of the squirters (accelerator pump nozzles)? If so, then you have gas.
2. If you do not see gas squirting, then fill the carb like described earlier. Just dribble some gas into the float bowl directly. Use either of the top vents to get gas right into the carb. Once that's got gas in it (you don't need much), then try the throttle lever again. Is gas squirting now? If yes, try to start it. If no, it might be time to pull the carb apart to see what's going on.
3. Find out exactly what the choke is doing. I know you've checked it and noted some of it's actions. But see if you can determine for sure that it's opening slightly when the engine is cranking. Heck, you can even mess with the choke plate by hand and see if all the linkages are free.
Clean and lube as needed.

4. Back to the ignition. Get out your handy-dandy multi-meter and put it in DC-Volts mode. Turn the key to the ON position (not ACC in this case, but fully ON) and check for voltage between 8 and 12 at the positive side of the coil.
4a. While you're at it, pull the small Brown wire back off of the starter relay and check for voltage there as well.
4b. While you're at it, separate the connectors at the ICM on the fender and see if you have 12v at either the Red or White (or sometimes Blue) wire on the body-side connector.

Sorry I can't think of more at the moment. I'm sure I'm leaving something out.
If you don't see voltage where it should be, report back again and we can offer further testing steps to track down where the power ends and where it needs to get to.

Paul

 

coil voltage = battery volts if I ground the meter to the negative batt post. If I ground the meter to the truck the voltage is <8v
starter relay I wire voltage is = to battery
red or white wire on the connector with 2 wires (I assume that's the body side on since it goes thru the fire wall) have little to no voltage. Red wire at the most gets 1 volt. There was some kind of white pasty grease in the connector (I don't think that connector was ever pulled apart) probably electrical grease.

Carburetor has fuel, choke moves smoothly
don't have time at the moment to try starting (the truck) to observe the choke operation

 

Well, that’s something!
The connector coming out of the firewall to the ignition module should have 12 V when the key is in the ON position. And then the other wire should have 12 V when the key is in the START position.
Actually, both should have power and START.
Without power to the ignition module, you will never get a reliable spark.

Sounds like a problem with either the ignition switch, or the wiring between it and the module.
Usually, it’s an ignition switch issue, but that’s no guarantee.

But another thing is interesting. While the 8V reading is expected and acceptable, why is it different if you put it to the battery directly?
Makes me think that there is a voltage drop due to a bad ground possibly?

 

Is there still a good wire from the battery to the body? Sounds like the big cable to the engine is fine, because it sounds like it cranks the starter just fine. But grounding the body is just as important for a happy electrical system if there is still one, Maybe unbolted from the body and clean the area around it. Then reattach it.

Oh, and yes, the grease was probably some electric or dielectric grease used to seal the connectors.
As ugly as some of those connectors got over the years, I’ve never experienced, or even heard of, a failure through moisture intrusion!

 

I don't see a wire from the negative or positive side (obviously) of the battery that goes to the body? There was a thicker green (and red one on the + post for the same reason) wire from the negative side that far as I was able to tell it only went to diy camper plug stuff that involved house wire nuts with some plastic wrap and electrical tape to go with. All that was got rid of months ago before this issue arose.

 

I would suppose it possible to test continuity between those wires and the ignition switch and test the switch at the same time.
Unless the things that stopped working in the cab has to do with a bad ground, I wouldn't be surprised if there is a messed up wire somewhere.
The coil voltage was more around 6-7 volts than 8V, if thats been a ongoing thing that was never noticed would that cause detonation if the coil doesn't get the enough voltage?

 

Sometimes a weak spark can cause all kinds of issues. Including that.
But a normal factory ignition should put out plenty of spark, even at 6 or 7 V. But not much less than that.

I would start by adding a ground wire or two or three to the body.
At least 10 gauge wire. Does not have to be battery cable size. But it should be 10 gauge.
Straight from the battery negative to the body over by the fender is a good start. We know there’s a little getting there already, because the starter relay needs to be grounded to the body. but that’s pretty minimal, So adding a good ground wire is still a good thing.
And if there is not one already in existence, you should add another one between the back of the engine to the firewall. The factory did this, but for some reason, a lot of people remove them. I guess they think it’s too much of a hassle when they’re working on the engine to put it back.
I wouldn’t use an intake manifold attaching bolt, but there are plenty of other bolting points available on the back of the intake. Or you could use a bell housing bolt. But those are harder to get to. Whatever is convenient and gets a good connection to the body.

 

Main issue:
I found the ground cable from the engine to the body and cleaned it up and it helped the coil voltage tremendously, It now reads ~10.5V. I was able to start my truck again and after I drove it a mile to warm it up. I came back to shut it off to see if it would start and I don't even turn the key just lightly touch it and it cuts the ignition... But if I was really careful I was able to start it again. So it sounds like the ignition switch is worn out.

Side issues:
The detonation wasn't as bad as usual but that wasn't much driving. So it may have been helped by one of two things: better coil voltage or potentialy richer carb setting.

still no guage lights or dome light, Seat belt buzzer + light non functional to. All of those were functional within the previous year

 

Yep, kinda sounds that way.

Yep as well. Maybe... Or it just decided not to rear it's ugly head for the moment.
Either way, better is better! Even if temporary...

Could be multiple things at work here.
Check under the seat, or under the dash, or wherever your year buzzer module is, to make sure it's has not become disconnected.
I forget where they are, but I thought for '78 and '79 they were in a rectangular white-ish plastic module under the seat. Might be thinking of other years though.
Dash lights, don't forget to turn the ****/rheostat back and forth to see if anything lights up. And click it to see if the dome light illuminates with the switch.
Might be a door switch issue, a ground issue, a burned out bulb issue. Or probably one or more of half a dozen other things.
Check fuses AGAIN. Even though you've messed with them probably multiple times, check them again. Verify that one or more of them have not burned out while you were messing about.
The '79 should have the later model (10-fuse) fuse panel. Pretty sure that there is a separate dome light circuit, as well as the really tiny instrument cluster lighting fuse. It's the only fuse that I'm aware of that has it's own circuit dedicated just from the light switch to the lights. So you have some fuses powered all the time, some that are powered only with the key in the ACC and ON positions, and the one that's only active when the headlight switch is pulled out one or two notches.
You may already have known all that, but I figured it was worth bringing up.
In the heat of battle we often forget to re-check those things that we'd just checked the day or so before.

Paul