I have a '90 FLSTC that suddenly had a weak taillight. In fixing that, I noticed whenever I tested the turn signals, ALL of the lights slightly flicker with the interval of the turn signal flasher. Electronics is not my strong suit so I don't know where to begin other than to check grounds, & they all seem to be ok. I'd sure appreciate any suggestions since I'm sure this is just the beginning of something that will reveal itself & bite me when I least need it or expect it. Thanks in advance.

 

Check the wires under the rear fender.