Weird Tailight Problem Solved

Problem started with a LEFT brake light out .
Changed the bulb. seemed to work fine
then a few miles later the turn signal ( a separate bulb) started hyperflashing
then a few miles later before I could get home and check it out , the left signal stopped hyperflashing , but the tail light would dim with every flash of the left turn signal .
then It started hyperflashing sometimes if I hit the brakes with the turn signal on.
So I started troubleshooting , checked bulb to assure correct bulb and install, all good.
Checked for wiring faults to the tow hitch, nothing obvious
then I wiggled the plugs behind the tail light and got a momentary change for a fraction of second .
evidently there is a jumper between the harness and tail light with connector plugs in and out to add a tow package
removed the connectors and the contacts were full of whitish green powder , similar to battery corrosion .
Cleaned up the terminals and it is all good now.
would have never guessed a corroded terminal could act that way, I was ready to start chasing wires with the Fluke meter
Thought maybe this post might help others

 

Resistance does weird things. Can seek grounds through unexpected sources etc

 

Another one I have experienced is frayed/corroded wires hiding inside the insulation where it cant be seen and can cause loss of connection and even arcing causing voltage spikes .
Wire and terminal jiggling is an essential diagnostic tool.