I have a 05 Dakota ajust the other day the left rear singal and brake light quit, also the "headlight on indicator" dash light remains on all the time, even when the headlights aren't on. The left blinker also blinks 2 or 3 times faster than normal. Has anyone seen this before. I have checked the bulb and it checks good........ Any ideas.......

 

check all of your fuses in the fuse box to the right side of your engine (looking head on at the truck). If any are blown replace them and it might fix it. But by the way you're saying that the left signal blinks faster (which is to indicate that THAT side would be burned out) and the headlights on indicator light is still on, that to me says something is shorting out somewhere in your electrical system. I recommend taking it in to a service center and having them take a look at the electrical system to see if anything has accidentally come loose causing the systems to short out.

*EDIT*
I did have the fuse for my parking/tail lights on the passenger side blow one time because of a mistake I made, and it made that side blink really fast. It's the fact that your headlights indicator light stays on that is kind of confusing...let me know if it was just a fuse

 

Reading the factory service manual, the entire circuits you are having issues with are controlled by the PCM computer. They have a bevy of test procedures for what you describe. Also, the PCM may just need to be reflashed or rebooted. They say disconnect the bat and reconnect may reboot the PCM though this NOT in the FSM I have read this Reboot procedure.