Fusible link or grounds?

[Chanman09]

I took my 86 c20 out for a great little drive today.

She’s a little cold natured, but after she was ready I drove down by the lake and enjoyed the wind in my hair.

I pulled back into the yard and put her back into her spot and killed it.

Then, I remembered I was going to cycle the ac and heat through all the settings to make sure my vacuum hoses were still ok and that they would pull the vent doors closed and switch to feet and defrost and bilevel. 

I went to crank the truck again and no start.

And, the radio quit. I pulled the headlight switch and didn’t have lights either.

So I went and jiggled battery cables and the headlights came on.

I had dash lights and cab light. But when I turned the key, nothing


I thought maybe there was some heat issues with the starter so I let it sit for a couple of hours.

I just went back out there and realize there’s no power to any ignition, and the things that controls - radio, blinkers, fan etc.

So, I’m going to go testing tomorrow.

Obviously I’ll start with the easy stuff an go from there. But with my luck it’s always the hardest and most time consuming thing that it ends up being.

What are y’all’s  bets??

A wonky ground? A fuse? A fusible link?

I’m going to pray it’s the - battery ground at the alternator bracket. But I have a feeling it’ll be a fusible link at the starter.

I’ll end up on my back in the cold dirt cussing that I don’t have a third hand to hold a starter while I lose the bolt or washer from the starter lug. 


Such is life.


Anyway, any cool things I might need to look at before I cry too much??

Thanks!

[bd]

...So I went and jiggled battery cables and the headlights came on...

Make sure that the battery cable connections to the battery, starter, and engine are clean and tight, and that the copper strands of the cables aren't corroded where hidden under the insulation or severed by corrosion or fatigue.  If the cables check out okay, give the fusible links a firm tug to see whether they stretch or separate.  An '86 should have two fusible links at the starter and two fusible links at the firewall junction block above the back of the engine.

[zucchi]

Don't underestimate the importance of good grounding. Thoroughly clean all grounds; engine to frame, body and battery – frame to body, battery and engine – battery to body, frame and engine. The body has lots of components, so; fenders to firewall, firewall to hood, cowl to door, etc.
Think of grounding like insurance; it's better to have more than you need than not enough.
Redundant grounding is, admittedly, tedious and boring and usually doesn't "solve" an acute problem but getting it done eliminates that variable. You'd be surprised what systems and assemblies poor grounding can affect. The worst I've seen was a transmission that needed a rebuild after only ~60k regular miles. Upon inspection, the bushings were eroded. It was ultimately determined that current flowed through the transmission so as to get back to the battery. You see, current is like water; it flows the path of least resistance. If a circuit is incomplete or poorly grounded, current will flow through a related or shared circuit to find ground. In the case of the transmission issue, current flowed between the output shaft and clutches to the case. Electricity was arching between the shaft bushings and the shaft. Aluminum bushings don't hold up like the tungsten contacts used in relays and ignition points.

I also second what the other replies recommended; clean the wires and contacts at the battery and starter.
If you're still having issues, use a multimeter to check for voltage at the distributor and solenoid.
If everything tests ok but the starter solenoid won't engage, use a remote starter switch to confirm the problem is with the starter rather than the ignition switch.

Keep us ported.

[fiddler]

Start by removing the battery cables from the battery and thoroughly cleaning the battery posts and the cable connections inside.  In that you had intermittent contact jiggling the battery cables the problem would seem to point in that direction.  Use a wire brush on the inside of the cables.  Not sure what kind of battery you are using, but what you are describing sounds like a corroded battery cable issue.

[Chanman09]

Forgot to update y’all

I went out to the truck and started checking grounds. I took a flappy wheel and hit the alternator bracket for the main ground and also the frame and block in the front part of the engine bay.

I jacked up the truck to follow my red cable to the starter and checked it was clear of any pinches or frays. It was fine.

I then went to checking starter connections.


Poor little fusible links fell off in my hand. They looked like drowned worms when you fish without catching anything. They’re from 1986. And they sat in a field from 1996 until 2023. And I’ve dropped and replaced the starter more times than I’d like to remember over my tenure due to numerous reasons, but the main one being exhaust manifold problems.

I got up top and pulled the metal tube that houses all those wires that go down there and checked continuity between the new end if the wires and the junction area where the wires parted ways.

I got out the ol soldering iron and shrink wrap and found the right gauge wire to make new fusible links. The tricky one was the Y shaped link that was just a pain to get soldered solid. I needed an extra hand.

I got everything wrapped after checking new continuity and decided to put a ford style solenoid on the firewall. I debated on this, but I’m not lying about those dang exhaust manifolds. There’s no room for anything and I didn’t want to chance pinching or burning my new fix, so I did the dastardly deed of modifying and using a ford idea on the ol square. I know…I know. Please limit your vegetables being thrown to soft tomatoes.

I double checked that everything worked a few times and mounted the wires in a more eyeball friendly manner and haven’t had any issues yet.

I got a newer, larger fire extinguisher to carry in the cab, and I’m glad the old links did their job.

Thank you all for the help!!

[bd]

Forgot to update y’all ...

...I got everything wrapped after checking new continuity and decided to put a ford style solenoid on the firewall. I debated on this, but I’m not lying about those dang exhaust manifolds. There’s no room for anything and I didn’t want to chance pinching or burning my new fix, so I did the dastardly deed of modifying and using a ford idea on the ol square...

Thank you all for the help!!

I considered this very modification on multiple occasions.  Exhaust heat baking the starter would result in labored cranking or no-crank situations.  But I found that even minor exhaust leaks from the manifold junction to the cylinder head or a cracked manifold was nearly always the culprit.  The solution was to mitigate the leaks by installing new manifolds and bolts, using torquing compound on the threads, the proper torque, and a smear of high temperature copper silicone sealer on the flanges.  To remedy heat baking the starter solenoid, I installed a factory heat shield.  Cooked wires has always been a problem.  The solution there was to replace damaged wires using wire with SXL rated insulation, firmly crimping then soldering terminal ends with 60/40 rosin core solder, and finishing off with marine grade, dual-wall, adhesive lined, polyolefin heat shrink.  Foil wrapped, fiberglass split-loom was used around the wire bundle to ensure protection from subsequent radiant heat.

Glad you found your solution.