1992 K1500. Blinkers were working normally then when the brake was depressed, they would blink rapidly. Now when the lights are on, the flash once and then every 10-15 seconds.
Check the blinker relay,if good check the bulbs.
It was the ground!
Glad you figured it out.
Looking for a Used C/K 1500 in your area?
CarGurus has 884 nationwide C/K 1500 listings starting at $2,500.
Search Chevrolet C/K 1500 Questions
Chevrolet C/K 1500 Experts