I have my lamp out light going on & off. I have checked my bulbs and they are good to go. Last week I was hooking up a car hauler and there wasn't any brake/ turn lights coming on the trailer with my truck. Is there any way to check the plug in to see what is going on or am I just missing a fuse?

 

You have a separate fuse for the trailer lights check the fuse-box cover for the layout. The lamp out has nothing to do with the trailer lights,it can be any of the bulbs going bad or the circuit board on the rear light bulb holder is known to go out on these as well (pull each bulb and check for heat damage)

These are handy for tracking down trailer connection problems:

http://www.etrailer.com/Tools/Tow-Ready/TR20117.html

 

In the 05, I think that the trailer fuses are #42 & 43, I just replaced the left side fuse on my 05.

 

Do you get the consistent dinging of the Lamp Out light as you drive down the road? That is what I am seeing right now. It goes crazy for a minute or two then stops for a bit. Only seems to happen on the highway and by the time I get to my destination the Lamp Out signal goes off. Annoying and I'm not ready to break down and take it in to have an electrical gremlin traced out (just don't want to spend the $$ yet).

I will look at the bulbs for heat damage but would love to find the root cause.

BTW, I have 2004 2500.

 

Pull your stoplamp bulbs and check for melting of the plastic base. They tend to melt which gives intermittent contact with the tracks.

 

For the lamp out issue, I suggest looking at/replacing the bulb holder/circuit boards in the tail lights. These parts have been updated to help prevent the lamp out issue. Worked for me. $20 each from the dealer.

Not sure this would be related to your trailer light issue though. My trailer lights issue was tracked down to one of the three non-replaceable relays in the fuse box. Check your fuses (three of them: parking, left turn/brake, right turn/brake). If they are good, your relays are probably bad. $500 to replace the fuse box. I bought a TowReady Modulite HD which taps into your brake light harness for signal. Much better set up.

The only way to know for sure is to start probing wires at the trailer plugs and go forward until you either find a broken wire or you get to the fuse box.

Hope this helps.

 

Mine has done the same twice......all the bulbs worked fine. Both times I found some over heating signs with the left stop bulb. I replaced it with a quality bulb from NAPA and used a lttle di-electric grease on the connects....this solved the problem.

 

Fought it for years, replaced the rear tail light bulb holder/circuit boards and problem solved.