These codes represent the left and right rear turn signal output open / general failure information.
I noticed the other day when using the turn signals the indicator lights would blink a couple times then begin to be a rapid flash.
When I was able to get off the bike at work to check all lights I noticed all the blinker positions and all lamps worked normally yet the dash indicator was a rapid flash.
I took my scanner home to pull these codes B2151 & B2156.
I accessed the BCM to monitor and command left and right blinker by-passing the handler bar switches, both the indicator and each turn signal location blinked normally.
I cleared the codes and pushed the right turn signal switch to monitor switch on / off signal and saw it was normal, and the indicator began the rapid flash again and reset the code B2156.
I installed the Kuryakin front driving / blinker light kit that trims out the radiator inlets about 1 1/2 years ago.
At that time I performed the Sync to BCM procedure and have had no issue with the operation of the blinkers.
The day before I noticed the rapid blink from the indicator I did accidently Turn'd on the 4 way flashers, and did push the right turn signal switch while thinking I was turning off the flashers, this is the only thing I can think of that may have caused loss of the Sync to BCM.
I will try to perform the Sync to BCM this evening to see if it returns to normal.
Just wondering if I should have the trailer plugged into the lighting harness, I'll try both ways if needed.
Has anyone else have this happen after such a long time from when the add on light / blinker kit being installed?