Why Is My Silverado 3500 Trailer Left Turn and Brake Light Not Working?
Updated 09/08/2026 | Published 09/03/2026
Question:
Left side turn and break lights dont work with 4 and 7 plug, fuse is good, whats the next step?
asked by: Dan
Expert Reply:
Hey Dan, thanks for reaching out. Since the left turn and brake signal is dead at both the 4-way and 7-way, that points toward the truck rather than the trailer connector itself.
If you already verified the left trailer stop/turn fuse, my next step is to put a circuit tester directly on the left stop/turn terminal at the 7-way while someone operates the left turn signal and brake pedal. If there is still no power, check the Trailer Interface/Lamp Control system fuses, then inspect the wiring and connector behind the bumper for a loose pin, corrosion, or damage.
Did the left trailer light circuit quit suddenly, or has it been intermittent for a while?
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