I have an 01 ultra with a big bore kit, V-H pipes and pc2. I will be going down the road and it will just die, it restarts when I shut off switch for a few seconds and turn back on, I still have all lights and radio so not a main breaker.

 

Try wiggling the switches while going down the road to see if you can duplicatevthe problem.
Start cleaning connectors and add dielectric grease.
Unhook your pc2 see if that helps, clean those connector also.

 

Could be a faulty main circuit breaker.

https://www.hdforums.com/forum/elect...rspective.html

 

Buddy of mine just had the same thing happen to his ...(but 09" R/G)..first found a bad connection on the battery negative side , fixed that ,then it did it again...checking things while running it in shop , got an error "system relay" ..swapped out the system relay and has been running good with no problems since..FYI .... will drive you nutty for sure ....!!!

 

When it cuts out does everything turn off - lights etc. That will tell you if it's the circuit breaker tripping. More often than not, the actual eyelet crimp was bad and the wires were getting so hot they were tripping the breaker.