Towing Issues: electrical problem, gmc savana, hazard switch

Question
QUESTION: i have a 1997 gmc savana, the brake lights, park lights,and
instrument panel lights quit working at the same time, I've
checked all fuses.

ANSWER: Where you towing a trailer when it happened?

---------- FOLLOW-UP ----------

QUESTION: no, but all of my towing connections were old and corroded and i disconnected them

Answer
If everything was working before modifications then start process of elimination. Did you check all the fuses by sight or with a voltage meter? Any other related fuses or relays, some are in the engine compartment. Also check the harness behind the rear bumper, make sure nothing came unplugged. Wires that could have been disconnected from the harness could also be wires for the tail lights. If all is good there it is possible something shorted out in the headlight switch or multi function switch, which is the turn and hazard switch in the steering column.