Yea, definitely seems backwords. The inverters we have in the ambulances are not that way. If you are parked than the truck has to be in high idle before the inverter will even engage. I havent really noticed an rpm change when engaging the inverter while in park. This makes me belive that it wouldnt put too much stress on the system if you were using 400W while driving. There has to be a hack but if not, there are A LOT of aftermarket inverters that can put out just as much if not more. Even Wal-Mart has something like 750W inverters by Black&Decker.
I am resurrecting this thread because today I hacked my inverter so it's continuously set at 400w output even while driving. The below procedure needs to be done at the rear of the truck, behind the 110v outlet.
1. Pull the outlet cover off the trim panel and unplug the molex connector from the back of the 110v outlet.
2. Unplug the molex connector with the 9 wires from the inverter.
3. Locate these two wires on the molex connector: Violet w/ Red stripe (you can barely see the red stripe in the photo) & Blue w/ Yellow stripe.
4. Cut and cap both ends of the Violet w/ Red stripe wire.
5. Do the following with the wire which is Blue w/ Yellow stripe:
Cap off the end that runs toward the front of the vehicle. Ground the end that runs to the inverter
I don't take full credit for this hack. I found quite a few threads on the Taco forums but nothing on the FJ. I and was able to find both a Taco & FJ inverter wiring schematic so traced the hack from the Taco's inverter's schematic and figured out which wires applied to the FJ's schematic and it worked. For those who also have Tacomas, this is what I found:
Taco ---> FJ
Violet White --> SPD Combination Meter ---> V-R ---> Violet Red - Cut & Cap
Violet --> NSW - Park Neutral ---> L-Y---> Blue Yellow - Cap off the end that runs toward the front of the vehicle. Ground the end that runs to the inverter.
Can you also post a photo of the work after the changes have been made?
I wonder if there is a way to make it so you don't have to turn that outlet back on again, every single time you start the engine (I keep forgetting, after each fuel stop on long trips, then my back passengers have to remind me as their batteries begin running down).