Urgent problem zero electric power solved… I’m an idiot

I mean, you could run a jumper from the battery + to the terminal in the fuse box.
But that wont get the truck to crank.

It would get the window up.

The bigger the jumper wire. The better.

Just don't crank the truck. You'll be pulling way to many amp through that small wire.

 

Well now get this I did put a jumper from battery to that positive stud in the box and it sparked like crazy. No blown fuses when it happened I don’t have any big cables here at the house but I’m working on getting some

 

Ok......hold on a sec.


Take your voltage meter and go from the POSITIVE post of the battery, to the wire in the fuse box.
Tell us what the reading is.......


KEY OFF. Key off....... make sure the key is OFF.

 

did you try a voltage drop test. It’s how I would start diagnosis.

https://youtu.be/xerAp9Yd53Y?si=kM2xNi-RovsZZa_T

 

You need voltage to do a drop test. We don’t even have voltage.

 

Key is in the house for safety

12.34 volts

 

There is no power getting to the main positive feed post inside the fuse box. (If there was, this would read 0.0 volts, i.e. because the battery's positive voltage would be "getting to" that post inside the fuse box, as it should in normal circumstances.)

The challenge w/ your setup is that folks on TW forums don't know the extent & details of the aftermarket changes that have been made to your stock wiring, to accomodate your 2nd battery, inverter, DC/DC, etc.

So it's a bit of a mystery why there is no power getting to that post in the main (stock) fuse box in the engine bay. Are there aftermarket cut-out or transfer switches in your system? Are there other in-line fuses (for example in add-on fuse blocks and/or in-line "bullet" fuse housings on cables) that are part of your 2nd battery setup?

 

To be clear, I'm just asking if there are other switches, fuses, etc.

Without knowing exactly what is going on or how things are set up I don't recommend "just trying stuff" as there is the potential to melt, burn, or blow out components accidentally.

 

Yeah.......
That means the cable in the fuse box is grounded somewhere.

You need to trace the wire in the fuse box to where ever it goes.

 

Do you have a test light by chance?

 

Grounded, or I would think more likely disconnected (floating).

OP this is a stretch, but do you have a clamp-style DC current meter? If yes, you could use that on the main + cable coming off your main battery (under the hood) to see if significant current is being drained by a partial short.

I would not suggest using a traditional multimeter in-line for current diagnostics as those are limited to only 10 amps. (The multimeter's internal fuse will blow if >10 amps flows in current-reading mode.)

Example of a clamp-style current meter:

 

The 2’d battery is a lionph battery that is only connected to the truck through a dc/dc charger that at the moment isn’t connected to the truck battery at all. Does the positive battery cable have a fusable link in it? Except for the winch (which isn’t connected right now). I haven’t don’t anything to the stock battery system

 

And yes that mess of wires is embarrassing but it’s worked the last year and I’m ripping everything out and reorganizing when I build a new platform back there.

 

If you go from + to + you should see 0v.

I'd start by disconnecting the wire in the fuse box.
And using a test light from battery - to the wire.
Then from battery + to the wire.

Again, wire not bolted to the fuse box.

Confirm the issue.
Then identify the cause.

 

Has to be grounded, or it would read 0

 

You can check wire via a resistance. Unbolt it from the fuse box, and the battery.
Check resistance (continuity)

 

Oh, right. You're correct. My bad.

It is grounded for sure. Through either a high-resistance or low-resistance connection, TBD.

 

What’s that black cable that comes over the top, with the big connection in the middle wrapped in tape?

can you disconnect it and test positive to the terminal again?

 

sound like he does have voltage from body ground to positive terminal.

The point is to check positive battery terminal to positive cable, and negative post to negative cable. If both are “no voltage” then it’s the battery….

if one cable is good and the other is 12v, then that cable is bad.

 

I think I see the issue here, if the cable coming from that stud is the one I have circled in red it should be hooked up to the positive battery post not the negative.