electric

So the left turn works ok until you step on the brake? You may have a faulty ground? You might try a redundant ground for the turn or brake and see if it helps? If part of wiring is in lamp assembly and can't be accessed, you may need new lamp assembly? Don't replace anything unless your testing points in that direction. My biggest problem is I can't see anything from here.

helpful. also i checked the fuses and they are all good.where is the grounding wire for thee left rear lights.or where should i look for it

The ground wire is black. My info shows only one ground wire coming from assembly. Unless you can access wiring inside assembly, you can't separate the grounds. My info shows ground 401, but, I don't have location? I'd have to follow the wire.