I recently installed new rear tuirn signals on my 1997 fatboy. When i press the left turn button at idle the turn signals flash. Anything above idle and they just stay bright. I am guessing I wired it backwards. Sound right?

 

Hard to say. But, only you know exactly what you did and that's the first place I'd look. You're using good logic here.

 

i would think if you wired them backwards they wouldn't work at all.

 

Were the old lights 2 wire and new lights 3 wire?

 

new front and rear turnsignals went from 3 wire to 2 wire they all work at idle but the left one stays on not blinking when engaged at highway speed

 

One of those wires out of the three is a daytime running light . You probably hooked up the daytime running wire instead of the blinker wire. Check your wiring again.

 

but they work at idle only the left does not work while crusing

 

One of three things......bad light....wired wrong or a short.... I would grab a multimeter and start testing.
Only other question I would have is....Are your new lights LED's? If so you may have to install resistors.

Without being right there to look....hard to say.

 

yes the fronts are led the rears are bulbs checked wires they are all wired the same and no shorts
strange that they work at idle but not while crising..as you slow down it will work and its onlt the left side

 

I would assume that when your rpms are rising the voltage is also increasing in the wire enough to cause the leds to malfunction. Sounds like you will have to install resistors for the leds.