So, the inverter has two settings, one that requires the car to be driving (400W), and the other that requires the engine to be running but the transmission can be in parked position (100W).

I had an occasion when I needed to be charging a pair of batteries using the inverter, and nearly every time I restarted the engine after having made a stop somewhere I forgot to push that switch on. I wonder if there is a reason Toyota did not design the inverter port to be powered when the engine starts, and automatically switch to higher power delivery when the transmission is put in Drive.

Is there an after market switch that can manage this more intelligently, such as powering it by default when the engine starts and letting the driver choose the high power when possible?

If you have modded yours, what did you design?

Thanks

My solution was to put a sticky note on the dash .

you can do something similar but I wouldn't advise it. you can trick or modify the relay under the hood in the fuse box so it's always on. probably your best bet. or actually run a dual battery set up lol

Always hot power outlets **Pictures!** | Toyota 4Runner Forum [4Runners.com]

Thanks. I already have a dual battery with a LiFePO sitting inside; just don’t want to hook up an inverter to it.

You could look at something like this: In-Cab Inverter 400W In-Motion Wire Harness - KTJO 4x4

I'm not affiliated, not an engineer or an electrician. YMMV.