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Try pressing the hazard switch halfway down. Watch the turn signals indicators on the gage cluster to see if the lights come on. Fidget around with the hazard switch also to
see if anything happens. Usually there is a connection issue inside the hazard switch assembly and the turn signal/hazard switch assembly will need to be replaced. The brake lamp switch at the pedal runs through the turn signal switch assembly.
GM World Class, ASE Master
13 years at 1 GM dealer, GM World Class Tech, ASE Master Certified, 8 time GM M.O.E. award winner,