<VV> Brakes fixed, now light gremlins

[Grant Young]

Thanks to those who suggested I needed to back up and stop some more to fix my spongy brakes. All is well there now, BUT, I discovered another problem when road testing - no tail lights, almost. I have a left rear taillight that is on any time the key is on, except when the lights are turned on - then it goes out! The headlights (high and low) and brake lights work fine. The tail lights will come on one side when the turn signal is activated, but don't flash. Any trouble-shooting starting tips??? I am thinking it might be the main switch as the rear harness is new, and I have already gone through the brake light switch adjustment. Thanks again for all the great advise.
Grant