Rode the FXR into work today and suddenly the right side signals stay on. Started it up this morning from home and my first right hand turn I of course used the signals but I noticed that the turn signal indicator on my dash was getting dimmer with each flash then suddenly they just stayed on. Tried to shut off the bike thinking it might reset something but no dice, as soon as I turn the key to ignition, the signals on the right side stay on, left side works perfectly. It does seem that when I use the right side signal while the lights are malfunctioning, they get brighter, kind of like it's a running light with flash. The relays and breakers on this thing are original I'm sure, so my first thought is just to replace anything related to that. Any thoughts from the collective hive mind?

 

The turn signal module likely took a long vacation and won't be returning anytime soon. I had the same issue .... simple Visa card fix, module on the Fatboy was cake to replace ...

 

If the flasher took a dive, wouldn't both sides be acting up?

 

Assuming there are no aftermarket lighting components on this bike...

There is no turn signal module on a 1990 model HD.

The signals on both sides are powered by a simple flasher unit.

The problem is in the right hand switch.

 

Unless it's been added, 1990 FXR didn't use a module, it has a flasher.

Remove both bulbs, clean the socket and contacts then verify each socket has good ground. If that's all good, take the right handlebar switch housing apart and clean the switch. But my money is on a bad ground at one of the bulb sockets.

 

 

A bad ground will not cause the lights to remain on.....

 

Gunk can build up in the light sockets. Time and moisture make it happen. All sorts of weird electrical gremlins will appear with badly corroded light sockets. Pull the bulbs, clean everything with a wire brush, I like a small ball brush used for plumbing work to clean out the sockets. Then some dielectric grease and reinstall. 9 out of 10 times it will make all the gremlins go home. And it is easy and cheap. Good luck. PS, do front and back.

 

No aftermarket lighting has been added, all stock. I'll probably just replace the flasher anyway just because I'm sure it's original. Using a pipe sweating wire brush is a great idea to clean the sockets, I'll pick one up on my way home and see what happens. Great advice all.

 

That's logical Dan, but I've seen this anomaly countless times over the years on all types of vehicles.

With a 2 element bulb and deficient or no ground, when there is power to the low filament (lights on) normally that voltage goes thru that filament to ground (bulb lights up). With no contact between the bulb base and ground, there is voltage on the bulb base coming thru the filament. So rather than lighting the bulb, the voltage from the low then feeds thru the base to the ground side of the high filament and back to the indicators, on a simple wiring harness. Since the flasher is out of the circuit, nothing happens but the indicators now have low voltage because it's back feeding thru 2 filaments which are acting as resistors, so the indicator lamps are dim.