freightliner fld120 1997 tail lights problem

started today out with tail lights ..worked all day on the way home I had to turn the headlights on and no tail lights but if I turn just the park lights on they work..anybody have any kinda idea of what this may be...if I hit the brake the lights brake lights work ..but when the headlights are on I have nothing in the back..turn them off and the park lights on everything works great..

 

yea I have to get this fixed ...when I start the truck and turn the lights on all lights work after about 30 min. ride to work I have not tail lights..but if I flip the lights off and turn the park lights on all lights work......its just odd that they work sometimes and don't sometimes....

 

well guys thanks for the help .. I think I got it fixed today.....got off early and came home and turned the lights on to see if they would go out and they did so I left them on and started to look for the problem... took the plug loose check for voltage nothing went to cab pulled the cover from the relay and breaker compartment and started to test the relays and breakers...all tested pretty good but 1 was so hot (breaker) you couldn't touch it bingo took it out and took it apart its stuck closed all the time getting hot and burn it self up..glad it didn't burn my truck up....pick up a new breaker 8.00 and lights work and breaker stays cool....I know the other day when I started it that something would pop like it was going of and on and said what could that be but then it stopped that's the day I started to have problems ..it took me a while to find the problem and only a few min. to fix, but if I would have had 1 of those power probes I think I could have just went to the problem so I plan to order 1 of those here in the next few days.. you can power things up and test them and all with those things..

 

please tell me how to check this.. problem came right back today..

 

I checked this..no problem there