hello all, spent a few hours cruising around the forum before registering.
I'm having an electrical problem after washing my bike.
Its a mod bike.
I have pulled all electrical connections and blown them out, added dielectric grease, checked all pinch points, swapped bulbs out etc..

What the heck would cause this problem:
Turn the key to start, the left running light/blinker flashes ONCE then goes dark.
The rest of the electrical system works,headlight brake lights,right blinkers/running lights.

And the bike runs fine.

 

Welcome from NM.

My 2012 48 used to pop the rear bulbs after washing. I never used a power washer or anything just a regular old hose. I noticed that a tiny bit of water was getting in the bulb socket when this was happening. I put dielectric grease in the bulb sockets and started tying plastic bags over the rear signals/brake lights when I washed it and the bulbs stopped popping after every wash.

 

+1 on that ^^^
I also noticed that the signal lights are not very water tight.
They are probably your issue.

 

Yup has to be something like that since it turns on then off which means you have power going to the lights and its not a ground issue. So perhaps the electrical system is doing it's job by breaking the circuit if water is in the socket.