hazard light flash with turn signal on 2004 Chevrolet Avalanche 1500

hazard light flashes when left turn signal is applied. Does not always happen

2 answers
Intermittent problems with the turn signals can sometimes be attributed to a computer problem. I had something similar happen to me--completely intermittent and strange. I took my car in to the shop, and the onboard computer had every failure cataloged. They had to replace the turn signal module.
check combination switch