Waterdriver
Goblin Guru
I installed the same tailights.These are the lights I'm using.
I have the fuse box ripped apart looking for alternative brake light wires that only go on with the brakes.
I'll reassemble it all and document the exact symptoms.
It very well could be a ground issue. I only wired up one light for testing and didn't secure the ground permanently.
The headlights, blinkers, mirrors and parking lights work perfect without the brake wire plugged into the taillight.
Due to how the Cobalt used all red tail
lights (running, turn and brake) I had wired the outer amber lights as running and turn signal. Red is running light and brake.
This might be changing thanks to JSATX's idea I saw for his.