Check for ground (most cases bad ground is the problem) Check for power getting to light sockets Check the bulbs
I have the same problem with my 06 Liberty. I think it has something to do with the trailer towing package as the problem did not occur until I noticed the lights stop working completely on my trailer.
It could be because its running out of battery
If you have a 1998 or newer it could be a fuse in the power distribution center under the hood. The whole trailer light system is fused through there.
You need to replace the daytime running lights control module
Make sure that the wiring harness is properly grounded. Baring that, there is probably a short in the wiring somewhere. A short means the two wires used in trailer lighting are touching someplace.
Have you checked the drl relay?
there is a fuse dedicated to the running lights on the 96 Thunderbird. Check your fuse panel under the dashboard for the proper fuse and check to see if it is blown.
Daytime running light module may be the problem
Check bulbs they are double filamented smaller for brake lights larger for tailights Check the fuse Check the operation of the stoplight switch
it would kill the batt.
Change light bulbs, they sell them at Wal Mart. Check relay and fuse in under hood fuse box. Fuse name DRL for day time running lights
Problem with it is the ground wire wont hold a load on a trailor with more than two lights-----ground it yourself to frame