I have a 2018 Roadglide Ultra with a detachable tourpack. when I remove the tourpack or disconnect the lights for it, the blinkers flash very fast. Like when you have a light out. All the lights are working. I do get error code for Tailight out.
What can I do to remedy this problem? all the rear lights are LED

 

With the tour pack off, and if you're using HD's slot lights in the back (Electra Glo Keystone part #67800598), the indicators will always blink fast when the tour pack is off... period... I chased it myself on my '16 Road Glide Ultra for a couple years lol You'll also noticed that, with your tour pack off, when you shut your bike off and the blinkers blink to indicate security arming, the back slot blinkers don't blink... thats probably actually why you're getting the error codes, and they'll go away with the tour pack on because the tour pack's lights blink on arming. If I remember right, I think the codes I was getting were B2151 & B2156. You can reset the codes, then use your blinkers and it won't kick a code as long as you don't let the security system arm... but as soon as the security system arms the codes come back, if the tour pack is off.

But I had a HD mechanic working with me on a few occasions trying to "fix" those two things (indicator flashing fast & not blinking on arming) and never could. The "problem", I believe, is actually in the internal electronic design of the Electra Glo Keystones. I came to this after working with the HD mechanic and talking to a guy over at Custom Dynamics... I think the HD Keystones has an LED controller in them and that controllers uses the "running lights" power to actually power the blinkers, so when the controller sees an input from the blinker wire it send power to the blinkers, from the running light's leg.. but with the bike's ignition off there's no power on the running light's circuit to power it. Thats kind of a real basic explanation... but I have never seen a 14 or newer with HD's Electra Glo Keystone slot lights that blink when the system's security arms.

The fix, I put on a set of Custom Dynamics ProBeam Fillerz instead, now they flash when bike's arming, indicator blinks at normal speed, and no error codes.
Also, you can leave it the way it is, doesn't hurt anything... just a little annoying lol
If you're not currently using the Electra Glo Keystones... then none of this may apply!

 

I have the same issue with the HD lights and one is busted so I ordered the CD fillerz, I hope I get the same results as you. thank you..

 

I’d bet it will, IF you had/have a factory Tourpak on your bike, and the signal’s indicator is blinking fast and you’re getting those two codes when the Tourpak is off, and no lights flashing in the rear indicating when the security arms. No amount of “training” will get the signal’s indicator to slow down or get those lights to blink on arming.

Kinda ironic, I like the H-D ones, but even with the revisions to them they still function the same way... it’s not that big of a deal, you get where the indicator blinking fast doesn’t bother you, and you know what the error codes are coming from and they clear when you put the Tourpak on, but...

I like the H-D one’s looks, but I just find it humorous that the CDs plug into the same connector and they worked flawlessly lol they are brighter, they look good too, and they’re a $100 cheaper than the H-Ds.