First off my pickup is a 1996 3/4 ton.

I have never had a problem with any of my lights until now. Bought a new trailer the other day and when I hooked up the trailer lights noticed that the brake lights are constantly on, for both the pickup and the trailer, with the key off and not using the brakes. The left blinker also wouldn't blink, it would light up but be solid. The right blinker worked fine.

A couple days after towing the trailer home both blinkers on the pickup stopped working. They both would light up solid but not blink.

Went to auto zone and replaced the flasher fuse and it worked for 20 or so miles and now they're back to not blinking and being solid.

I tried searching old posts but couldn't find anything on this. Any help is greatly appreciated, thanks.

 

Sounds like some sort of short. What kind of plug are ya usin? if you have a constant power back there like on a 7 way RV plug, you might have the 12v constant shorting to the brakes. If the trailer has a 4 flat, the brake lights use the same wires as the turns, green and yellow. If using an adaptor or somethin from a 7 way to a 4 flat, you could be supplying power to the yellow wire via a crossed wire. I would get out the trusty test light and when it's actin up see where you are gettin power from.

I used to work on tractor trailers, and electrical issues usually have to be taken step by step, tracing and seeing what is hot and what is grounding. It can be frustrating, but with some time, it's not bad to figure out.

 

Blinker fluid needs to be changed to synthetic. -or- use the type 4.

 

I had a similar electical prob on my old Chevy. When the fuse blew, the electricity found the weirdest paths through the different components. When the signal light fuse blew, the lights came on just like yours AND my dome light came on. Totally bizarre. I know my post won't help you solve your probs just saying that what you are seeing is not unusual when fuses blow. How a blown indicator fuse can make my dome light come on is still a total mystery. I stopped trying to figure out that weirdness and got the trailer wiring redone.

 

High Bid you beat me to it!

 

I almost said it, but decided to save it for someone else

 

autozone and oreillys didn't have blinker fluid, do you think napa might have some? haha smarta$$

 

I've had better luck using genuine Mopar fluid. If you are running LED bulbs you will need to switch to a higher viscoscity fluid.

 

Check the ground first.
Then check all the lights/bulbs to see if someone didn't replace a dual contact bulb with a single, or rewire something incorrectly.

 

I'm thinkin what Shovel said.

Sounds like something is crossed up in the connection or the trailer wires.