A clicking noise may be noted from the turn signal flasher after the turn signals are switched off. This is commonly cause by a faulty turn signal switch which will require replacement.Google+
Car Problem Reports
Chevrolet Silverado 1500 Turn Signal Switch May Fail and Cause Clicking Noise
Chevrolet Silverado 1500 Problem
Average Mileage: 145,688 mi (123,000 mi - 180,000 mi)
Visitor, 1999 Chevrolet Silverado 1500, 157,000 mi
"clicker" comes on by itself. stops if I depress the brake.
Most annoying, turn up radio.
Visitor, 2002 Chevrolet Silverado 1500, 180,000 mi
same as the other folks
Visitor, 2000 Chevrolet Silverado 1500, 123,000 mi
Turn signal clicking noise continues on its own without lights being activited.