I posted this in the security thread but thought get more hits in this thread and hopefully a answer.

My key light went on this morning when I cold started my bike to go out on a errand, stayed on for bout 5 seconds then went out after I started it...hmmm. Got to my errand and shut her off and came out to start it again(warm) and the light then went on again for bout 5 seconds then went out. This is the first time something like this has happened.
I thought the engine light had to come on for it to make a DTC code, not the security key light
I went into looking for a DTC and came up with code U1097...fine... something with Loss of Speedometer Serial Data to ECM...maybe its a old code so I cleared that code (BTW there were no other codes present just the 1 in all the catergories).
Went out again to get a pack of smokes to see if I have another code waiting for me and did the diagnosis and...nothing, no codes but also the key light didn't stay on like the 2 previous starts.
I changed both fob batteries this spring and I installed one of those Radio Shack sirens till I get ahold of a factory siren

Someone got a idea to why the bike did this?

 

it is a code from historical data (not an active problem), meaning at some point in the past you lost power. I would check your battery cables, a loose ground could of caused it. If you have replaced the battery, or a fuse that maybe the problem. Have you done any work on it lately?
I have a thundermax, which gets a random code for no real reason, its a problem with thundermax.
Start with our battery cables. I bet your ground to frame could be loose or need to be cleaned.

 

I assume its a older code, so now learning today how to reset those codes and now I will have valid codes comming up. I replaced the battery this spring and added a Independent Control Auxiliary Lamp kit in around that same time. It could have triggered that U1097 code but I'm curious to why the key light did its little song and dance this morning and if someone else mighta had the same thing and a plausible cause.
If it happens again then I'll have to probe deeper into why.
IMO this information this was a nice find and for all of us to still don't know everything here's a link to give it a try and check it out.

https://www.hdforums.com/forum/elect...tic-codes.html

 

I don't have a security system and mine did the same thing. I did have a plug wire problem, and when I cleared the code, the key light hasn't come back either.