Bus dead electrically - what else to look for?

[70bus]

The bus is in the local shop to sort out brake/shift issues I could not; it was started several times and driven briefly; all worked. Today shop calls and says car is dead as doorknob second time they tried to start it.

No start, no lights.

On my home-made wiring diagram, it looked like my engine-bay fusebox fused the starter so I got a big lecture about that (I didn't - as far as I know! - so have to send them a cleaned up version). I've told them the electrical path is: Batt POS -} starter lug -} fusebox -} cab fusebox. If the engine bay fuse blew, it's 30A, so that will be interesting. They didn't mention checking the cab fuse, but I would think an 8A fuse would blow faster. My guess is that a wire came loose off the ig switch due to tow, and shorted to dash the second time. However, what else would cause the sudden and complete electrical death besides those 2 suspects?

Starter, solenoid and gen all newly rebuilt by reputable old schooler. Gen polarized. Battery brand new. Neg cable does have a screw-off knob, but they checked that. I know it's hard to remote-diagnose, but they didn't sound pleased and I'm trying to save them some diagnosing time.

Pics show the starter wiring and the engine side, but before I ran the striped starter wire to regulator. I'm also including my cleaned-up diagram; when done laughing at my photoshop skills (or my setup), see if any errors jump out? I did suggest they pull the tach wire off the coil, but that seems unlikely to short whole shebang...

Technically it’s still not correct, but there’s only so much space… the striped wire goes from starter to reg, and instead of battery to reg the other wire goes from reg to fusebox feed - which connects to battery. Bad practice to connect a wire to battery clamps… Anyways.

thanks to MThompson, who made the base of my diagram (in Tech archives).

_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[RWK]

First and easiest thing I would try is a different battery, seen many "new" batteries with a dead cell that acts up occasionally,
_________________
73 Type 181
63 Type 113
63 Type 261- 428 071
62 Type 241-378 025 178 530

[2Pack]

I'm sure they'll check that 30A fuse first, but I wouldn't be surprised if it were blown. The starter solenoid could get close to 30A on its own. If there were any other loads (lights etc.) on when they cranked it over that could put you over the limit.
_________________
Please buy my Treasure

[70bus]

Shop called; no blown fuses. They suspect a bad ig switch; a drag if so, because it's a rebuilt one and should be good for decades. They will pull it and see.

Good point about the solenoid, tho - I couldn't find a small fusebox that went over 30A. 40A up boxes were the size of tennis-ball cans! I mean, you can probably put a 40A in this one, but the housing may melt first.

I am curious, if the starter is getting power straight from the POS cable, how would the solenoid blow the fuse? The f30A use should be just for cab wires, and if anything the ig fuse in cab should blow. Just trying to bulletproof things...

Shop did tell me I overthink shit. :)
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater

[2Pack]

Overthinking might be bad, but understanding things is always good.

The starter motor gets its power directly from the battery, but the starter solenoid gets its power at Terminal 50 from a circuit that goes through that 30A fuse, up to the ignition switch etc and back to the solenoid (but not through a fuse in the cab). The solenoid will have an initial inrush of current (~30A?) to build up a magnetic field that moves the parts inside, then a smaller current (~10A?) to hold them in place. The starter itself could draw ~300A.

By the way, I like your "as-built" wiring diagram. That's something the shop should appreciate.
_________________
Please buy my Treasure

[Eric&Barb]

Could be a connection that seemed tight, but has loosened up. Did that with a positive battery cable. Tightened it down and it must have been tilted a little somehow jamming in the threads of the stud on the solenoid, so it did not fully tighten properly. Went on trip in cold wet weather, and had to push start it once, and again, and got home to find the problem.

BTW your axle boot looks like the seam is pointing straight up. That seam does not flex properly in the up down direction of the axle flex and thusly will tear up the boot all too soon. Rotate it to the 3 or 9 O'clock position as seen from the wheel on that side.
_________________
In Stereo, Where Available!

[70bus]

Thanks. I'll rethink things if I blow that 30A.

Shop appreciated the chart, except the one I gave them at first had the POS going to fusebox before starter... now THAT could have been an issue! And no doubt sent them looking in wrong place. Oops.

They did say that "my chart had that enginebay fusebox upside down; the big fuses were on the bottom in real life." I pointed out that that is how the factory does the wiring diagrams - fusebox is upside down in them! They had to give me that one. :)

E&B, you are correctl That is an old pic, and I have since rotated the seams to one side.

UPDATE: as I suspected, a wire had popped off from the headlight switch to ig. Because I overthink things, the shop went for the complicated reasons first. Not a bad suspicion, to be honest :)

For whatever reason, that wire in the WW harness is pulled too tight and does it from time to time. I guess I'll need to make an extender. Crimping tighter sometimes works, but once you've deformed the spade they break faster in my experience...
_________________
Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams

Raul the 65 singlecab

Karl the 70 nine-seater