Ignition Fuse Popping

This one should be fun. On the way back from a beach trip this past Tuesday, with the woman I married Friday, the 4 runner broke. Rolling up to a stop sign, it just died suddenly. After some searching, I noticed the ignition fuse was blown. Figured it could just be a couple wires behind the box, and I did find some small tears. Taped, separated, new fuse, no problems. Drove it up to Charlotte Thursday (3 hour trip) with 0 issues. Once we got to the house, we decided to get lunch. On our way, it died again. Same fuse. Messed with it and separated the wires again, and after a few attempts, it roars back to life. We get home, and hours later decide to get dinner. I get in the car, turn the key, pop. And it’s been here since. We’ve been messing with it and I have gotten it to start a few different times, but it always pops again at some point. I have 0 specific factors for you all that could be causing it. I thought it was bumpy roads at first until we got to the house and it kept doing it. Turn the key to “on” and it pops.

I’ve unplugged the passenger side ECM, Alternator, gauge cluster, and the efi relay. No change. I had a diagram of the fuse and it says it powers the “generator, airbags, charging warning light, combination meter, and efi relay” which is why I unplugged some of these things. I don’t see any burnt up wires anywhere, and I’m at a loss. Stranded at my brother in-law’s, only a select few tools, no transportation to the store (he’s out of town), and a $300-$400 trip home even with triple a. Someone give me an idea lol.

1. Trailer Brake
2. Aux Beam
3. Underhood light
4. Lightbar/ditch lights
5. Radio
6. Amp/sub
7. Aftermarket taillights
8. CB radio
9. Maybe some other stuff? Can’t remember at this point

 

You'll need a multimeter to check for a short to ground, but you definitely have a short going on. Somewhere there is a bare wire rubbing another bare wire or the chassis.

That image is unreadable.

What is the fuse name that is popping? What is it labeled in the fuse box and its location?

 

I put it in the title, it’s labeled “ign”, otherwise, ignition fuse. The image must lose some quality when I upload it here

 

Yeah, the site is resizing the images.

Regardless, that fuse goes freaking everywhere. I think you'll need to check for shorts starting at the fuse and ruling out various circuits at the different junctions. You may have to unpin some connectors to narrow it down.

 

I uploaded the full sized images in a zip file. They should be easier to read.

 

If I read things right, you mostly have that fuse going to B-R and B-L wires. B-R = Black with Red Stripe. B-L Black with Blue Stripe.

....and I found a little more:

 

I’ve unplugged just about everything. VSC module, airbag module, ecm, starter relay, and maybe some other stuff I’m forgetting. Still stumped. Can’t even find a car to rent to get home and we’re stuck 3 hours away lol.

 

It touches the ECM (like four times), Stop Light Switch, COR, Combination meter, Ignition Switch, Noise Filter, 3 Coils, alternator, and a few other things.

I don't see the air bags though.

 

If I unplug the ignition switch, it doesn’t short, but I imagine that’s because the circuit no longer gets power. Maybe I’m wrong though, and the ignition switch is a problem?

 

Do you have anything aftermarket hooked to this circuit? On those color wires?

Aftermarket electronics are evil things that destroy everything they touch.

It sounds like you don't have a multimeter...can you rig a test light? Pull a headlight bulb and hook wires up to it.

https://www.youtube.com/watch?v=Lfk-vmeK4G0

 

If you look at the first schematic I posted, the ignition switch is before the fuse...so yes, the fuse doesn't have power. It's what's after the fuse that's causing the issue.

 

I have a test light. I do have a multimeter, it’s my emergency one. To be specific, it’s harbor freights 7 function one for like $6. Nothing aftermarket wired into this circuit that I know of, I listed it all in my first post.

 

Small revive. I did make it back home with the 4 runner. It died while on the highway back home and I started ripping connectors out of the interior fuse box until it stopped grounding. It stopped after I unplugged the 1 pin SRS connector. I’ve been driving it fine since, and now I’m trying to fix it as after I unplugged it, my horn also stopped working. And yes, I checked the fuse for the horn. All good there. I have both the SRS and Horn schematics, and literally nowhere do these two intertwine. So I’m a bit lost where to go from there. I need the horn fixed for inspection soon, so a bit imperative that I get this done. I’ve got the entire dash off of the car tracing the gray/black wire that goes from the fuse box to the SRS computer. I’ve pulled the wire all the way to the center of the car where it starts going down and have yet to find anything. The harness starts to wrap around the metal dash frame and it looks like a royal pita to undo, so I really don’t want to do it lol. Any ideas?

 

Looks like you are narrowing it down.

Sucks but that metal frame can cut through a harness.

You could always run your own wire instead and just give up on finding the exact place that wire is grounding.

 

It might also be the SRS computer has shit the bed and is causing the issue.

If it were me, I'd put my meter on continuity and the leads on the wire and ground and I'd wiggle and pull and tug on that wire and watch the meter. If it doesn't do anything, I'd suspect that the srs computer you said it goes to was bad.

 

Yea, just did that. It beeped steadily, so the wire seems fine. Don’t want to buy a new computer without fully ruling it out, but seems to be that way hmm