2004 GMC Sierra 2500 HD Q&A

2004 GMC Sierra 2500 HD Question: When using right turn signal, all four blinkers flash

I checked all related fuses and disconnected the rear main harness & trailer plug connector and all appears fine, no corrosion. Even with the rear harness connector and the trailer connectors both disconnected, I tried the RH turn signal and all four blinkers flash including the mirror signals in my factory extendable mirrors. Any idea what I should check next. Oh, one more thing, it used to be an intermitant problem when it was rainy/humid and cold conditions but recently it dry outside and the issue has been going on since Friday Sept 24/10. -
Answer 1
Do you still have this problem? It possibly the flasher relay. Its located on the left side behind the dash on the driverside. Its a pain to get your hand on and the part is about $75 from the dealer. -
Comment 1
No, problem has been fixed. It was the flasher but I picked one up at an auto wrecker myself and cost me $10 Cash. -