The body shop adjusted my rear hatch when it was repainted after vandalism and now tapping the brake lights makes the gauges light up. I had a similar problem on my 86 TA where the brake would turn the rear defrost on. Not 100% sure this is the wiring in the back but I think the connector back there could be the problem. If anyone has any experience with this annoying problem please let me know thanks in advance.
JMFNX@AOL.COM
1989 GTA

 

My turn lights dont blink and I checked the board if someone replaced the turn signals with one element this would make it jump and I assume it might affect the turn indicators also.
JMFNX@AOL.COM
1989 GTA

 

YES it will affect your dash lights, look at all the bulbs in your rear lights and make sure they didn't mix up the placement, if you put a single element into a socket that is meant for a double element bulb it will bleed power into the other systems.

P.S. if the wire for the rear window defroster gets unhooked from the hatch strut every time you hit the brakes it will turn on the defroster. I think it only happens when you disconnect the passenger side strut wire.