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
GMC Yukon XL 2500 Turn Signal Switch May Fail and Cause Clicking Noise
GMC Yukon XL 2500 Problem
Average Mileage: 119,450 mi (71,000 mi - 175,000 mi)
Visitor, 2000 GMC Yukon XL 2500, 78,000 mi
When putting on left or right turn signal the 4 way flashers will come on.
Visitor, 2004 GMC Yukon XL 2500, 71,000 mi
turn signal makes clicking noise when signals are off.repair estimate $200.00
clicking noise stays on after you've completed your turns. no flashing signals, just continuous clicking noise. happens either direction, and comes on even when directional signal was not used, just simply driving.