You more than likely need resistors if you're new leds don't have them built in. Because leds draw so little compared to your regular bulbs, the car thinks you have a bulb out. Same thing happened when I did an led conversion on my front turn signals. They would work fine with my lights off but acted up once I turned my lights on.
Sent from the future.
2012 Kona Blue 3.7L V6:
Borla LT headers, O/R h-pipe, Borla S-types, 3.73 gears,
Steeda adjustable UCA w/ mount, BMR LCAs, Airaid CAI,
LCA Relocation brackets, AE driveshaft, GT 80mm TB,
Black 18x9/10 2010 GT500 Wheels w/ Nitto NT555s,
Eibach Sportline Springs/shocks & Koni STR.T Struts