This can be a shorted power wire to one of the lights or a light bulb has had a problem in the socket maybe. Please remove the brake light bulbs to inspect. Here is the brake light wiring diagrams so you can see how the system works.
Check out the diagrams (Below)
Please let us know what you find. We are interested to see what it is.
Images (Click to enlarge)
Monday, January 29th, 2018 AT 2:03 PM