The P1575 DTC does NOT light the MIL lamp on the dash. If you connect your OBD and connect TuneECU and do an error check it will show up with a dialog box saying the switch check must be performed. The speed of doing the switch check isn't critical, but making sure you get them all is, miss one and it still won't work. Or if one switch isn't picking up as it should it won't work.
From the shop manual:
The following switches will be checked:
• Front brake switch
• Rear brake switch
• Clutch switch
• Twist grip cruise cancel switch (operated by holding the twistgrip in the fully closed position)
• Cruise control accelerate switch
• Cruise control decelerate switch.
A malfunction of any switch will not necessarily cause a DTC to be stored and may prevent the cruise control from operating correctly.
If you do have a single switch failure when the dealer tool is connected it will prompt the tech to activate each switch in turn and won't proceed until each switch registers as 'good' during the procedure so if you have to wait on the dealer at least there's a positive way to getting the cruise back without guessing. If you want to try it again yourself, I recommend you pull the headlight fuse so that you have max voltage to each switch, put the bike on a trickle charger wouldn't hurt and then run the test with engine off and ignition on.