I have a 2003 2500HD 4X4 duramax. the right t-signal comes on when I press on the brakes, does not flash just comes on, I can see it on the dash and the signal in the right mirror comes on. the t- signals and flashers work all t- signal bulbs are flashing. also when I put on the right t-signal and apply the brakes it stops flashing. the left side is working fine. any ideas? Edit. just noticed while out looking at fuses and bulbs. that when the right t-signal is on the cab brake light is flashing and the upper bulb an the left side is flashing which I believe is the brake light bulb. every thing is normal while using the left t signal.

 

Never mind. figured it out and fixed it