Sorry for the long delay. I was on a 90-day cruise. I first installed the ST2 brake module device on my 2016 RT a long time ago. I can't tell you where I wired it because I sold the bike. I now have a 2022 S2S. Before I left on my cruise, I ordered a new ST2 module. I plan on installing it next week. The connector you want is located on the left side of the bike. Lift your passenger seat and you will see a large multi-connector on the left side of the bike. This is where you can grab the Orange wire (Power); the Black wire (Ground); & the White wire (Signal). The diode needs to be placed on the signal line going back to the bike's brake pedal. The ST2 device sends out a positive voltage spike to the brake signal line which causes the cruise control to drop out. Your schematic diagram is good.
Here comes the scary part...
You have to cut the white wire into two wires. Leave enough wire on both sides so you can make your connections. You will need a meter to measure the voltage on the two white wires you now have. The one that has 12 volts when you hit the brake pedal is the one going back to the bike's brakes. The other white wire is the line to the brake lights. Put the Anode of the diode on the white wire that goes back to the bike's brake pedal (the wire with the voltage). The diode's cathode will be attached to the signal wire coming from the ST2 module and the white wire going to the bike's rear brake lights. I don't remember for sure what diode I used. I have a bunch laying around here. More than likely it was a 1N914. You just need a 'fast-switching diode' that can work with very small signals. The tilt of the module is critical. By tilting it, you can control how sensitive to your deceleration it is.
Please note: The ST2 module requires about a 4 mph sudden drop in speed to trigger the device at its most sensitive setting.
Since I have not installed it yet on my new bike, I cannot say for sure if you will need the special starting procedure. But just in case, I found that if I put my foot on the brake and then start my bike, I cannot engage the cruise control. The ST2 module goes wonky. Additionally, it appears to need a charge before it can operate correctly. So I normally start my bike and back it out of the garage, and then shut it off waiting for my wife. When I go to start it this time I follow these steps:
1. Turn the key to the ON position. DO NOT Start It Yet **** DO NOT TOUCH THE BRAKE ****
2. After about 10 seconds, I put my foot on the Brake and hit the start button.
3. The system should be active now. When you get up to cruising speed you can turn on your cruise control. If you downshift with at least a 4 mph drop in speed, it will trigger the brake lights. It is pretty hard to do this around 30mph. I find that I have to be going about 45-50 mph to see the speed drop enough to have it light up my brake lights.
**** After you ride the bike for a while, you can shut it off normally; but when you start it back up, you need to follow the steps 1,2,3. The system will be warmed up already and will work fine. Just remember if you cannot get your cruise control to engage, then the ST2 module has not initialized correctly. Stop the engine; let all of the lights on the dash go out; then follow steps 1,2,3 to start it back up.
I do mostly long rides in the country, so I am on cruise control almost all the time. Is this thing the best device in the world - NO. But it does work! I assume it has a small spring-loaded pendulum type device inside, which when jarred, hits the 12-volt line and sends that signal out. I don't know for sure about that because I have not opened one up.
Again, sorry for the delay in answering. I hope this helps.
