Drove home from work this morning and noticed my left turn signal came on several times along the 14 mile trip. First I thought I was just sleepy and accidently hit it. When I got home it came on again. I let bike idle in driveway and it occured several times back to back. Turned motor off and kept ignition on, no signal. Started motor and signal came on. Vibration related, I do notice that left grip shakes alot. Any ideas on how to cure? Bike is 2004 FLHTC with 14000 miles, mostly stock.