Up through the 2018 models:
The 22-690 is typically only needed if running LED turn signals on the front AND rear of the bike.
*If only running one set of LED turn signals, install the 22-300 Smart Flasher to correct the flash rate if needed/desired.
*If installing LED turn signals on the front AND rear of the bike you can correct the flash rate one of two ways:
Install the 22-300 Smart Flasher and one set of the 22-690 on the front turn signals.
Install two sets of the 22-690, with one SET installed on each of the front turn signals. This can help make for a cleaner install as there typically is not enough space to easily install the 22-690 on the rear of the bike.
Due to the newer can bus style systems, and error codes that come into play, the best fix for installing LED turn signals on BOTH the front AND rear is to install 1 set (2 resistors) on each front turn signal.
This tricks the system into thinking the stock turn signals are still in place.