Turn Signal Problem???
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
If everything is stock there are a number of possibilities. Poor ground somewhere in the flasher wiring, poor bulb connection in a bulb holder, poor contact in a wiring connector. These 'electrical' problems are often mechanical! They just need chasing down and sorting out.
Road Warrior
Joined: Mar 2010
Posts: 1,290
Likes: 7
From: D/FW Texas
it's possibly something as simple as the flasher itself needs changed. Do the lights flash slow in both turn and hazard modes? They are 2 different flashers. Swapping in LED lamps without adding the load equalizer will usually cause the system to flash extremely faster, not slower.
Road Master
Joined: Jun 2009
Posts: 1,062
Likes: 18
From: Beautiful SW Missouri Ozark Mountain Country
The reason I ask is because when I tried to install LED's on my '90, they flashed extremely slow. I've heard that some bikes will flash really fast, really slow, or not at all. My friend's '89 flashed really fast. Badlands cured both of ours. But you are running the stock bulbs, so I lean toward a ground issue.
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Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
Take all your flasher bulbs out, check they are all the same wattage. Usually they be 12V 21/5w, if you have some 12V 23/8w or something like that in the mix it could go slow like you outlined.
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Seasoned HDF Member
Joined: Dec 2004
Posts: 11,068
Likes: 1,473
From: Texas! Ya mean there's someplace else?
Flash speed on an older bike with a "flasher" depends on 2 things - resistance and capacitance, aka an RC circuit, with a time constant that depends on the values of R and C. The capacitance is set by the flasher unit and it will change some over time. The resistance is essentially the resistance value of the lamps as well as the entire circuit resistance. Bad grounds can increase the system resistance and cause an increased constant.
My '87-'90 Big Twin parts catalog shows only 1 flasher, so it would seem it is used for both turn and emergency. Of course, it is an HD catalog, so there may be an error! If there is only 1 flasher, change it and see if helps. If the flasher contacts are crusty or burnt, the resistance increases and the flash speed slows; can also cause the lights to be dimmer. Also, there are "heavy duty" flashers that are used when adding more lights - think of a car towing a trailer - and they will flash slower than a standard unit.
My '87-'90 Big Twin parts catalog shows only 1 flasher, so it would seem it is used for both turn and emergency. Of course, it is an HD catalog, so there may be an error! If there is only 1 flasher, change it and see if helps. If the flasher contacts are crusty or burnt, the resistance increases and the flash speed slows; can also cause the lights to be dimmer. Also, there are "heavy duty" flashers that are used when adding more lights - think of a car towing a trailer - and they will flash slower than a standard unit.
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,199
Likes: 3,087
From: NW AR
FLHT's of this vintage (pre smart-module thingie) have two flashers: One for turn and one for emergency. They can slow down for various reasons mentioned above (except the RC thing, they are thermal, not RC controlled). You can replace the flashers with a universal "OK for LED's" module for a few dollars from about any auto parts store. I did that on my bike, which was also flashing slow. I got them at Advance Auto Parts. The flasher you have in there now is an ancient design used in 50's Corvettes, if I recall. Anyway, the flashers are inside the faring by the right fork. The new modules will be a different shape and take a bit of mashing to get in there and maybe some minor connector fiddling. The original one didn't fit the holder either, and none of it is visible. As a bonus, you can change to LED turn signals if you want at a later date without a "load equalizer" resistor when you change out the flashers with what I suggested.