fuses blowing in reverse?

Hey, need some help !

Have a 2010 Tacoma with factory tow package. Just bought a new travel trailer and cant get the darn thing out of the yard because we keep blowing fuses. When initially plugging in the 7-prong trailer male into the Taco female, all is fine...have brake lights, turn signals on the trailer, all is good.

As soon as I put the Taco in reverse, everything goes, can't shift out of park, lose trailer lights. Replaced the fuse twice. Today at the trailer shop someone said that since the trailer has no "backup" lights there is a "blank" or dud in the male 7-prong, but that the Taco female has a "live" wire and that is what is causing the problem.

Thoughts? This is driving us crazy !!!

 

Finding a wiring problem is an involved and time consuming process. It could be a truck wiring problem (like a chaffed wire under the truck frame), or a problem in the adapter/connector, or a wire fault in the trailer. Who knows?

Something may be wrong with the "adapter". Some trailer wiring (7 pin) has a circuit connected to the back up lights to stop the surge brakes from working when you put the vehicle in reverse. Whether or not you have surge brakes, this can very well still be the problem.

So, in your 7 pin connector there is some pin that is used for this and for some reason it seems to be shorting out and blowing the fuse.

That's my guess.

 

For a different reason, I was blowing that fuse and it drove me nuts for hours. I am going to suggest something you probably have already done but it is where I would start.

My trailer is 7-pin and does not have reverse lights and it works fine. So that won't cause the fuse to blow. So starting at this point, the first thing I would do is looking at the trailer plug and the position used for a reverse light. Be sure the position wire is vacant or at least the wire isn't grounded. My guess it somewhere that wire is grounding from the trailer plug or after it.

 

x2,if it doesnt blow when disconnected,its the trailer

 

We are going to check the trailer's "plug-in" today today to make sure that is 'dead'. Didn't think the problem would be the Taco end since it is all still 'factory' and nothing has been modified/updated, and it is brand new! Know that doesn't matter and it's possible there could be a factory defect (!) or the like.

Unfortunately, the trailer's dealer mechanics are at a loss and the Toyota dealer already put in 2 fuses and no one seemed to make the connection of what could be the problem????

Hopefully we can get it figured out today! Thanks for the suggestions. Will update you as soon as we know.

 

I'm betting on misterquad's solution.