Electrical NIGHTMARE. Any advice is appreciated

05 Toyota tundra 4.7l DC 4x4. I’m an idiot. I am a carpenter and I thought it would be helpful to be able to charge my battery’s in my truck. I have a utility box bed cover with tool boxes on the sides. I had some old welding leads that were in good shape so I soldered copper lugs on the ends and ran them from the battery down along the fender behind the booster and down to the frame where I cable tied them to the frame and ran them to the back of the cab and up to the bedcover. I ran them to a on off switch but I didn’t put a fuse on it anywhere. It worked great for the little inverter I had in the box. But Friday I had to haul a truck across town and I didn’t have a spare battery so I soldered some more lugs on leads and ran power to the winch on my trailer. I didn’t think to insulate the connections and when it started to rain I shut the box and BAM I think I grounded it bc smoke started rolling from somewhere when I realized what happened I opened the box up and flipped the shut off switch. The smoke stopped and the truck kept running. I thought I dodged a bullet because every thing still worked. Until yesterday I hauled off the tuck and when I got home I was going to tidy up the cable on the winch. Hooked the leads up same as before but kept the connections from touching anything. Started to bail out cable while I held tension on the cable and the truck died. The engine quit running but the starter was trying to turn it over. I ran up and shut off the switch for the leads and got in turned the key off and the starter was still was trying to turn the engine over. Even with the key off. I disconnected the battery and disconnected the leads from the battery and hooked the battery back up to the truck and even with the key removed I can hear the starter come under load then when I put the key on and turn it to start the engine nothing happens unless I press the brake peddle. Then it turns over but won’t fire. I switched the horn and starter relay to check the relay and no change it seems to be getting power even with the key removed. But only enough to turn the motor over when I press the brake Any suggestions will be much appreciated.

 

So the starter is constantly engaging?

how long did you leave the trucks battery disconnected for? Have you gotten it load tested?

 

I mean, let's be real here. In general, it sounds like you're rigging up your truck in ways the manufacturer hadn't intended, and the issue you just created could've fried any of about two dozen different electrical systems in the truck. You could be chasing this shit for weeks, months, or you may've just FUBAR'd your truck, electrically. It doesn't take much to melt through a wire inside a factory loom that you'd never find in a million years without testing each individual circuit for continuity, and figuring out which harness was cut.

With that out of the way ...

Before getting totally nuts here, start with the obvious. Vehicles in generally have a number of protections in place to avoid overload like that. Let's run on the assumption that Toyota properly protected all of their circuits in the truck, and you probably just blew one of the critical fuses.

If you have lights on in the dash when the key is forward, given you're saying the truck cranks, but won't turn over, I would start by looking at the fuel-related fuses in the engine bay. I'd pay extra close attention to the "EFI" related fuses, but also anything A/F, fuel injection system related, etc. This will be more than one fuse. Also, I would look through the window on the square fuses to make sure none are clearly melted.

And if you really want to test my theory, if you have a can of starter fluid, shoot a 2-3 second shot of it behind the throttle plate, then try to fire it up. If the truck starts or stumbles, you know it's something in the fuel delivery circuits/fuses that's fucked.

 

Need a little more clarification but it essentially sounds like he joined the two battery terminals (with extra steps); which if for just a brief sec should be fine, but the potential problem could come from that amperage running through the frame which should be ground… but a little difficult to follow on what exactly happened

 

I believe I'm following what happened.

1) You soldered some leads to your battery terminals and ran lines from the battery under the hood to a power inverter in the toolbox with an off switch, but no inline fuse.
2) You then ran lines from your inverter / off switch/ whatever in your toolbox to your winch on a trailer and crossed the streams creating a flow of positive amperage through EVERY ground circuit in your vehicle.

A crude drawing, picture, diagram of what exactly you have done would be most helpful to ensure that I have this correctly.

You're not going to like what has to happen next. You need to first to remove all aftermarket / non OEM / electrical hackery from the vehicle. Next, get a muti-meter, a copy of the EWD and start checking each individual circuit in your truck. Every fuse, every pin, every harness. It will be a very long and suffering process.

 

There was a similar situation posted on the 4Runner forum where a guy had a no start after shorting his unsecured battery to ground due to it flipping over while driving. Turned out a ground wire was melted but he didn’t specify which one.

 

I removed all the dumb shit i right after all that happened but I held the leads up for reference. I took the intake boot off and sprayed starter fluid in and it hit a few times. Per shifty instructions. Went and bought a nice multimeter and I’m gonna start today looking for what I did. Still have to turn key over and press the brake to get motor to turn. But no fire without starter fluid

 

I appreciate you guys prompt responses. Thanks a million. Had a difficult week in the heat but I got this morning to try and find the issue

 

A couple years ago a similar problem was reported on this forum.

Problem: What is going on. My truck tries to start when I press my break with no key in the ignition and the truck is in park?!?

Solution: Found a bad ground on firewall going to the engine, replaced harness. All systems operate as normal.

More detail here: https://www.tundras.com/threads/pre...-in-the-ignition-and-truck-is-in-park.121297/

 

What Phil just tossed out is a good idea, and also jibes with melted ground Bryan pointed out earlier.

The fact it's turning over with starting fluid - and the reason I recommended doing that test - points to a potential problem with fuel not making it up to the rail, and I doubt it's because the fuel pump died. But think it suggests two things:

1. Whatever the issue is, it'll apparently linked to something in the circuit that facilitates fuel delivery. Wiring diagram for your '05 is here, Mamba linked above. Factory service manual/FSM is here. Fuel pump circuit taken from FSM is attached to this reply below, showing where all the components required for fuel pump originate (note: things like Crank Position Sensor are required to stay running). I'd start checking w/power at the relay socket. Important to note the pump shouldn't be 'hot' unless (a) the key is in START position or (b) the engine is running, as fed to the ECU by the crank position sensor.
2. You've just narrowed your focus from hundreds of circuits down to a dozen or two. (But again, I'd first be testing your major grounds for continuity)

You could further narrow things down by testing for fuel pressure while cranking.

Again, this PDF will help you with pinpointing circuits and performing some basic diagnostics, and that's where I'd start:

 

I'm Not very familiar with the newer computerized trucks.
With that said: if understand right your starter is turning the engine over, or at least energizing it with the key removed. In the older vehicles I have seen a couple instances where some add ons caused a short that melted the wiring insulation, and allowed constant hot wire to contact energize starter even when no key was in the ignition.
Not being familiar with how you set things up, and not having gotten into wiring schematics of the tundras myself I can't tell you where to start looking, but if you're at all familiar with them you could probably download a copy, and give you an idea where to start looking.

I would definitely start looking for wires, harnesses, and area of fuse, and relay box that don't look right.
There was one many years ago that had a melt in fuse box from an improper radio install that caused a similar situation. I found it when I noticed a dark area in fuse box.

Edit: Black mamba has a digram above