I actually write it down. Make yourself a "truth table." Go to the diagram, write down the colors and draw a picture of the column connector and kick panel connector.
Check the brake switch wire coming into the column connector. Should be hot when brake is pressed.
Check each rear wire LEAVING the switch. Both at the switch and kick panel connector, both left and right should be hot with brake switch depressed.
Now turn the switch one way or other. In left, you should lose rear brake light and left should flash
Opposite for right turn, etc.
These switches get AFU internally and can do really weird things.
As mentioned above check your bulbs.
