When I signal left (and only left) I will get 3 'blinks' of normal fashion and then on the 4th blink the indicator starts to go fast as if I had a burnt bulb somewhere - which is not the case. All lights on the truck are fine and operating but this has just started to happen. After about 10 seconds sometimes it goes back to blinking normally. Scanned for codes and nothing - replaced my TIPM about 2 months ago because of electrical issues. Any thoughts guys?