Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
Hello, does this pickup truck have an aftermarket trailer wiring harness installed into the tail lights of the truck?
Ok for it to cross circuits and do odd stuff its usually either an issue with an add on trailer wiring system which you said it doesnt have, An issue with the bulb connectors in the lamps front or rear corrosion, a loose ground or problem with a printed circuit board in the rear tail lamps if this model year uses them or problem with the multi function switch/turn signal. Inspect the lamp sockets for water intrusion and wiggle the turn signal stalk and see if the lights start working properly to start.