My 74 Highboy was running GREAT. Parked it, came out a day or two later, turned the ignition to start the truck, and NOTHING - I assumed I just had a dead battery. Got the battery checked, fully charged. Glanced at the fuses - nothing obvious there (possibly worth digging in more here?)

Replaced the starter solenoid, but then realized, the radio doesn't even turn on when I turn the ignition.

I know I should check better on the ground(s), but don't feel like overnight that would suddenly become a thing.

Do I replace the ignition? (I know, there's probably a simple way to test it right?)

Would love any suggestions/direction.

Is there a fuse specific to the ignition?

Thanks!

 

no lights? no seat belt buzzer?
if it's just the starter/cranking, you might check the neutral safety switch.

 

If the truck is completely dead from an electrical perspective I would check the fusible links particularly the one that comes right off the starter solenoid. I think it was orange on the factory harness. Check to see if it's gummy or stretchy. If it is you'll need to get another one and splice it in. The links are readily available at just about any auto parts store.

 

Thanks, ok, will look for the fusible link. Assuming if it's had, replace with another one? What would cause it to go?

 

I've never had a seat buzzer - I replaced the seatbelts and there was no electrical connected to the seat belts that were original.

And yeah, no lights, no nothing. The radio would always come on without hitting the starter/cranking, and that doesn't happen.

 

Then you need to check and clean all the battery connections as a start.
Would not hurt to check the ground at the motor and the frame and motor to firewall.
Dave ----

 

I'm gonna be a bit embarrassed when the ground is the problem.... this was one of the first things I was told to check, and I swear I did, but now I feel like I never actually did. Checking later this morning

 

Looking at the wiring from the solenoid - and while it's been like this the whole time, I'm curious if there is anything here that specifically needs to be addressed or if any of these chunky bits are fuses that need checking? (I'm afraid to pull them hard to see if they pull apart only to have the old rubber break and cause more problems:





And yes, I'm aware the previous owner has speaker wire running as an electrical wire here - guessing opening up wiring issues will turn into a hornets nest -

 

Yes, it's time they were all checked. You have a fusible link (the Brown wire on the battery side of the starter relay/solenoid) that has at least two splices already. And one that looks burned a bit, while the other end is bare strands. None of which bodes well...
I'm not even sure that you have factory tape there at the end with all the wires poking out. Looks like it was re-done at some point. But either way, I'd be unraveling it to take a peek inside. The bare strands are simply old age being sped up by nature having it's way.
The dead truck could be a result of a failed battery cable (either positive OR negative) but since your wiring is suspect visually, I'd start there.

On a '74, that might be a horn relay, or it might be something else. It's not the typical relay I see on later models, but it still looks like a horn relay to me. And the wire colors to the connector agree.
However, I'm guessing your horn does not work? The connector is not attached properly, since you can see one of the female connections hanging out in the air there.

The two large oval things are just connectors. You can pull them apart. And should do so now, while you're at home and can fix them if they break.
If they break, they were on their way out and you should replace them. Even if you're not well versed in wiring, you can learn to crimp/solder new connectors on to old wires.
The large cylinder thingy looks like a typical Ford splice (very robust and weather resistant) but does not seem to have multiple wires to need a splice? Maybe the short end of the wire to the connector is another fusible link? Don't think so, but it might be.
By the way, your fuses in the fuse panel have nothing to do with your problem. You asked if you should do anything with them, and you should. Take them all out, wipe them and the connection points in the panel clean, then re-install them. This should be done about every three or four years, since a layer of oxidation does build up on them that can impede the flow of juice when you need it most.
But they are not protecting any of the circuits you're dealing with. The horn relay, the main power from the starter relay, and some others only use fusible links under the hood. The skimpy/wimpy 5-fuse panel in the cab has just a few things it protects on a '74.

AS for what those other wires do, the larger Black w/yellow wire is your charge/power circuit. It's typically the largest gauge wire in the system and one section runs from the alternator's BAT output up to the starter relay's battery side and keeps the battery charged.
Another section of it runs from the battery side of the starter relay up and over to the firewall where it branches off to power up everything in the truck.
The Yellow wire(s) are for the voltage regulator's sensing wire, and the other Yellow is for the power to the horn relay.
The Green w/red wire is for the voltage regulator as well.
An ORange wire would run from the regulator to the FLD terminal on the back of the alternator.
A small ground wire (probably 22 gauge if I had to guess) runs from a GRD stud on the back of the alternator, over to one of the regulator's mounting bolts.
Any compromised connection on any of those wires will give you fits. Some will even leave you stranded.

I still say unwrap that tape to see what's underneath, and it's condition.
Find out where that speaker wire goes too!

By the way... Does your truck's instrument cluster have an ammeter to show the charge rate? Or does it have a battery warning lamp instead?
On that subject, does your regulator have 3 wire positions filled, or 4? And is it mounted on the fender skirt/apron, or is it up on the core support beside the radiator?
Seems like a '74 would have been up front, but I wanted to make sure.
Thanks for the good pics. If you have more pictures, we would not complain!

Good luck. Still more detective work on your part to be done.

Paul

 

Oh, and don't throw away the old starter relay! Your new one might fail in short order, so you should be ready for that with a good working spare.
You're not alone in making your first thing replacing the starter relay. Probably the most common first attempt at a no-start fix. Usually without the desired result.
But as a "bonus" you usually get stuck with one of the modern world's worst parts available. Unless you spent $50 or more on it? If you spent less than $50 on a new starter relay, it's a crap shoot as to whether you got a good one or not. Old beat up junkyard relays are often better!

So rule one, is don't throw away, or trade in any old parts for new, until you're absolutely sure it was faulty to begin with. Or that you got the right one, in the case of carburetors.
Slightly off-topic with the carburetor comment, but you have an old truck you're working on. Eventually you might be tempted to buy a cheap rebuild or "new" carb that apparently the Chinese (and other overseas manufacturing giants) don't feel is important enough to get them reproduced accurately for all years.

Rant over. For now...

Paul

 

I agree with 1Ton, I would be removing all of that electrical tape and seeing what is underneath. I too think it is probably a fusable link that needs to be replaced since you are getting nothing when you turn the key on. If you don't have a multimeter you can pick up an inexpensive one many different places and it will help a lot trying to figure out what is going on. One thing I cannot see in the picture and I am guessing in '74 they put them in a different spot than on my '79, but where is the voltage regulator?

Mine is right next to the solenoid on the passenger fender and the group of wires that is all taped up in your picture, at least on my truck, connects the voltage regulator to the alternator. '74 would have still been a points set up though and they may have put the regulator on the driver's fender where my ignition module is?

I also think that relay on the fender is for your horn.

Hopefully you can figure out your electrical gremlins, they are no fun to deal with.

 

So, upon inspection, I can't find an engine to frame ground - so I'm adding one today.

The negative terminal on the battery goes direct to the engine block. That's the only ground/where all ground is made from (aside from the speaker wire which goes from the battery terminal connector into the cab (hunting down where the speaker wire ground ends at)

Here's the requested relay pic:

 

Thank you so much Paul!
I'm about to go get some grounding straps to add from engine to frame. (there's no engine to frame ground - not sure if this would cause the truck not to start/do nothing - but it was running when parked and two days later nothing)

Oh... funny enough, the horn works (I think the picture makes it look like it's not plugged in, but it's on the post)

Regulator is in the above picture - mounted next to the radiator at the front of the truck (had no idea what it was til you mentioned it - should I be looking into replacing it?)

Just checked the speaker wire, looks like it runs ground from the battery direct to the aftermarket radio. can't imagine that would be the wire to chase down further? (I didn't pull it all the way, just found it connected to a bundle of wires that all lead up to the back of the stereo - but if you think it could cause the problem, I can pull it all out to check)

and here's the dash and fuses:

 

Thanks! Fusible link is still solid

Oh man, I have two electric volt meter things.... and still have no idea how to actually use them! :-( Electricity is like looking at a spreadsheet, my brain starts melting down quickly.

I'm taking today to try and trouble shoot then might call in a pro :-( but fingers crossed today fixes it!

 

and dang... I'll have to check if I held onto the old solenoid... I throw things away way too fast :-(