Where is the turn signal relat located on a 1991 ultra classic

Check the main fuse that comes off the battery.

This may help, but check all the fuses

https://www.justanswer.com/buick/61gr1-buick-century-no-dash-lights-tail-lights.html

It is a known issue!

https://www.google.com/search?q=1991+Buick+ultra+no+dash+lights%2C+tail+lights%2C+or+turn+signals.

..

Usually under the seat
Here's what they look like:

Duplicate question already answered

On an 03 bagger it will be under the seat. You'll have to remove it. Under the seat is the battery you should see a little silver clip towards the back ledge of the battery tray. That's the turn signal module. Remove the clip and pull the unit up amd out.

Not sure about the horn but speedo, signals etc are all tied together with speedo and TSM. What codes are displayed????

First you check that the left turn signal and brake switch wiring haven't been switched. I presume brakes and turn indicators use different bulbs. Then you check for shorted wires from wear or crushing where they go from headlight

I can't think of the name of the part, but I believe the two are related, and run through an electronic gizmo, that reads the speed/mph and shuts offs the blinkers. Turn signal controller maybe?

chk backwards to your turn signal control unit. The brake lights and rurn signals are routed in a way that would affect each other.Is this a four wire or?Chk fuses 1st. Good Luck- -Ned- A good grd is important.