Hi. I'm new here but am glad I can actually contribute something useful :-)
I had a real headache tracing the problem with my turn signals. When I first bought the car a week ago, one signal was faster than the other. After a day, when engaging the turn signal, I would just get hazard lights (both flash). Of course, I thought that meant the flasher unit under the dash was going bad (like most of my other cars that had this problem). Lexus wanted $89 for a flasher (other cars are $10 at auto zone, etc.!) so I decided to visit the junk yard. I tried 3 other flasher units and all had the same kind of results. This made me think there was a wiring issue. I had read on another forum that the SC's had issues with taking on water in the taillights so I though the sockets may be corroded. I took the left taillight out (the faster flashing one) and sure enough, the brake light bulbs were rusted right into the sockets! I tried for a couple hours to clean them out (after breaking the bulbs in the sockets) and eventually got them out and cleaner. They were still pretty jacked up. I put in new brake light bulbs (not turn signal lights) and the turn signals were no longer in hazard mode. However, one was still fast. I therefore thought that I just needed to buy new wiring for the taillights. I found a guy selling 2 tailights with wiring on craigslist and offerred to buy one (lucky, huh?). He agreed, I picked it up, popped it in and VOILA! Working turn signals. All's normal and good. So...long story short...
If you have this problem, replace the brake light or other taillight bulbs or replace the sockets and/or wiring they are in and you will be back in business most likely (if your flasher is still good and your turn signal stem is good, etc.)
:-)
McKay