I just hooked mine up to one of my trailers to test it, but their Australian site has a test procedure with a light that you could try:
https://www.redarc.com.au/how-to-test-tow-pro
If you got the Redarc harness, it is basically plug and play.
The hardest parts will be finding the factory plug buried in the dash and a bolt to ground the white wire.
The white Toyota connector is on the far left, deep under the dash and the white wire goes to ground, find a good bolt on the...
I think the Redarc guys that have posted on here said it works for all years 200 series LC/LX but you could always ask customer service. @REDARCRyan?
I purchased from eTrailer and they were good to work with and had everything in stock.
You'll want to buy the Redarc factory style switch blank...
Apparently I shouldn't be towing then. In the world I live in there are multiple causes of sway, wind being a significant one. But since I shouldn't be towing anyway, I'll leave that to the experts.
Unless you want to use the manual activation to straighten out a sway situation, or have to use it for an emergency. Seems like a BAD use for a phone app.