The exterior third brake light and all dome lights do not stay on and time out anymore, what could be the problem? They did at one time, now when I shut the door they go out right then.

 

When do the lights not stay on ?

1. When the doors are open
2. When the door is closed, and you use the interior light switch ?

Do you have any modifications to the truck like an after market RKE or remote start ?

Have you added anything to the interior light circuit ( i.e. added a TAC or other gauge that uses the interior light circuit ) ?

Few more details before we can dig into this one.
Have the trim level in the profile ( thank you for filling this out straight away !) what cab type is it ( Std or SCab )