So I got old MuleDawg home & well she is doing “ok”, but there are still issues. So here I am... The reverse lights are staying on regardless of position of the shifter. The 3rd brake light doesn’t light up... Also, I need a connect to find the door seals for all 4 doors as well as a instrument...
www.impalassforum.com
First please do not keep opening new threads on the same problem. It makes it impossible to know what you did in the past.
Has this car ever pulled a trailer? Dig around under the carpet in the trunk and look for extra wires. At the area behind each lens and on the driver's side rear fender where the factory wires come from the back seat and go to the left rear lens. Shorted rear wiring is a easy answer to your issues.
High/low beam switch is at the base of the column, the turn signal switch is in the column just under the wheel, the headlight switch is in the dash, and as you know the brake switch is separate as well.
I mention this as you would probably need several switch fails to have all the problems you are describing. It has a better probability of being a wiring issue.
RE: brake switch.
When unpluged do all lights go out?
When pluged in do all lights go on? Brake and backup?
Do the lights seem to be brite enough or do they seem dim?
A disconnected ground wire to the two lens would give you some but not all of your problems
Does anything change when you turn on the signal lights L/R?
Does anything change when you turn on the 4way flashers?
Do the front signal lights work?
Do things change when you turn on the park lights?
Have you checked the third brake light bulb? Whether the bulb is bad or lack of brake signal to it is good information.
You mentioned headlight fans? What type of headlights do you have? Are they connected direct to the OEM wiring or are relays used.?