Chopping up the inverter circuit

( Calling @Dm93 and @caribe makaira )

I have a factory inverter, and I am deleting the inverter to run a DC circuit in the console and in the bed. I would like to re-use as much of the existing wiring as possible (the DC feed for the inverter, the run from the console to the bed), and replace the factory dash switch with a simple on/off for the circuit.

Here's the circuit diagram:



If I still know how to read these things, it looks like the AC SKT relay is activated by IG1, and the factory switch commands the inverter to 100/400 (with the inverter complying or not based on other inputs to the inverter - speed sensor and ECM at least so you're 400W stationary/idle only?).

So, I should be able to use the AC SKT relay output at the inverter end (inverter pin 2), and control it via a new relay which is activated by a new switch using the existing pins 3 and 4 from the factory dash switch/pins 1 and 3 on the inverter end. Does that check?

As a bonus, does anyone know if there are female plugs to fit the factory dash switch harness and factory inverter harness, so I don't have to molest the harness?

Thanks.

 

I have a question and comment.

First does the output need to be switched separately from ignition? If not you could just ground the Blue wire at Pin 7 and the relay would switch on and off with the ignition switch.

Unless your planning on running the appropriate gauge wiring for 100 Amps to everything I would recommend either lowing the amperage of the AC SKT fuse or running the appropriate fuse sizes to your accessories at wherever you tap into the main power wire from the AC SKT Relay.

I don't know of any aftermarket switches that will plug into the factory switch connector.

 

I'd like to be able to switch it, but thanks for the suggestion, that would be a great simplification which is often a good thing with electrical.

Oh hell no I'm putting a couple resettable breakers in. The run to the rear outlet only takes <5A AC from the factory and I'm not ready to change it out yet. Eventually I want 50A back there for a compressor but for now I'll just re-use the factory run and parallel some 6awg copper later.

Yeah I'm not worried about the switch, I was hoping someone would have a part number for the female mate to the connector in the harness (if such a thing exists), so I could make a pigtail for a switch.

Thanks

 

I mean it's easy enough to do if you wanted to, I was just saying the relay will turn off with the ignition if you wanted to give it a constant ground.

No worries I'm just so used to seeing sketchy unfused/undersized wiring on stuff that I feel the need to bring it up.

That I don't know, that would be a question for @caribe makaira

 

Yeah, I'm actually really wondering about the factory supply wire. The fuse is 100A sure, but I don't really know that I like the size of it for an actual 100A, even in that short distance. Some automotive tables say 8 or even 10AWG are OK for 100A with an allowed 5% drop over short runs (5 feet) and high temp (80-100C) insulation, but I'm not even sure it's that big. I don't actually know how big it is, just have looked at it in passing some time ago, when thinking about this project. I'll get some calipers on the conductor when I dig in for sure, since I can't find anyone who has posted the info after quite a lot of scouring the digital trashpile. For now I'm only going to be allowing for a max 40A total load.

The factory inverter is pulling 34-ish at 400W - I don't really understand why Toyota would put a 100A bolted-in fuse on the run if they were only pulling 400W, especially since it's the only thing on the fuse. Maybe they downsized the inverter and never went back and altered the harness, or maybe they planned to offer a larger inverter as an add-on or something. There's definitely significantly more volume where the inverter sits to put in more hardware.

 

I could be wrong on this but these are my observations.

Fuses on automotive circuits it seems are generally sized where they run 30-60% of the fuses current rating during normal operation, the fuse is there generally to protect from a dead short rather than a slight overcurrent.

Modern vehicle wiring is at the low end of the very minimum size at best for the fuse size installed and in many cases branch circuits are well undersized for the fuses rating, that's why you should never ever put a higher rated fuse in place or you risk melting/burning things.

 

Oh yeah, I mean, don't get me wrong, I've wedged a gum wrapper and a screw into a fusebox in an actual emergency (bad starter that would work if you jumped the starter fuse - I figured if it didn't catch on fire while it was cranking and I pulled the fuse once it caught...), but seeing what a lot of people do with electricity in a car makes me wonder how there aren't more sudden vehicle fires happening everywhere on the street. If it works, it works, though, right? I wish I had to hand the pics of the Impala I instantly passed on when I saw wire nuts and the cheapest Chinese lamp cord in the world everywhere under the seats and in the trunk.

I think that and a lot of other things really speak to the safety margins that do go into proper professional engineering.

 

I guess people just have more luck than I do because I see the unfused mystery wires hooked directly to the battery all the time ran around through the door jamb yet somehow they never manage to short out.

I have had to deal with the aftermath of oversized fuses on factory circuits because hey if the fuse keeps blowing lets just stuff a bigger fuse in, it ain't fun to fix.

Not like the vehicles of yesterday that most of the wires could handle 30+ amps without melting, everything today has the absolute bare minimum gauge wire and terminals for everything. IMO that's part of the reason we see so many burnt terminals on things that use alot of current like blower motors, the terminals are marginally sized to begin with so any added resistance generates heat which causes the connection to get worse & make more heat eventually destroying the connection.

 

De-pin OEM and install these mating ones.

 

Thanks!

 

90980-

 

11099 looks like unobtanium, unless I can get lucky and find a used pull. I found the other as a piece of harness off a lexus and a couple NOS listings. It was worth a shot!

I mean, it does appear I could get one... at minimum qty 10,000 from the OEM catalog. I'm sure they'd have to go dust off some dies.