LED Turn Signal Problem and Resolution

[justintime]

A couple of weeks ago I bought a pristine ’15 FJ-09 from the original owner. The bike had 3,200 miles on the clock. By all visible clues the owner was a fastidious sort who was very careful in the way that he added the many accessories on the bike, including OEM Yamaha LED turn signals all around. The transaction went smoothly and I headed home on my “new” bike. Somewhere along the New Jersey Turnpike on my 200+ mile ride home I noticed that the turn signals were no longer flashing.
 
Once home, I put my meager skills to work to identify the cause of the problem. I had plenty of time to do this as all the shops in my area had a two to three week wait before they could look at the bike.
 
As mentioned, these turn signals are factory Yamaha LED units. They are, however, not available in the US. Their part no., YME-W0789-00-00, is not even in the Yamaha USA parts fiche. The original owner sourced them from Yamabits.com in the UK.
 
Here’s what I discovered and what I did about it:
 
Switch on the ignition and the front running lights would light up as they should.
 
Activate the right turn switch and the front running lights would go out, the right rear turn signal would light but not flash.
 
Activate the left turn switch, the 10A parking light fuse would blow (it’s the only 10A fuse on the bike).
 
I then focused my attention on the left rear turn signal and the turn signal flasher relay.
 
The circuit into the two wire flasher relay tested ok for incoming voltage.
 
The wire from the bike’s harness that supplies power to the left side rear turn signal tested ok for +12V.
The left rear harness ground wire also tested ok.
 
Obviously, +12V and ground to the right side was ok as that light was shining bright.
 
I disconnected the left rear signal from the bike harness. I grounded the ground wire and applied +12V from a spare battery to the power input lead on the signal. Instantly, the attachment wires got VERY hot. Looks (and feels) like a dead short within the indicator.
 
I sourced a new Yamaha LED turn signal from Kelly’s Cycle in Hamilton, Ontario. The part number is active in the Canadian Yamaha parts system.
 
After replacing the turn signal, the fuse no longer blew when activating the left turn switch and the left rear turns signal would light steady – no flash. In fact, all the turn signals would light steady when appropriately switched.
 
After a brief discussion with the folks at CutomLED.com who manufacture the special flasher relay needed to make the LED turn signals flash at the correct rate, I decided to replace their flasher with a new one.
 
After replacing the flasher, all turn signals, running lights and four-way flashers operated as they should.
 
Final conclusion:
 
Either the left rear turn signal was defective or a short occurred in the hook-up which smoked the turn signal. The turn signal short caused the flasher to fry, as well. The fuse did blow, but probably not soon enough to protect the diodes in the turn signal.