2010 Trailer Lights

I may not be the sharpest pencil in the box but this can't be right. Have a 2010 with tow package. Last night in the pouring rain, hooked up my little utility trailer to drag it home after loaning it out. Plugged in the lights and true to form, no running lights on the trailer. Turn and brake work fine. Much to my wife's chagrin, towed it home anyway. Today I start trying to chase down the problem. Fuses all good, bulbs all good!! What gives? So check for voltage at the connector on the truck. Nothing for the taillights. Time for wiring diagrams and thanks to another forum user, they are available. Again, I may not be the sharpest pencil but as I read the wiring diagram it appears to me that the tow/haul switch has to be engaged for the running lights to work. Is that for real?? What was Toyota thinking? Why would I need to engage tow/haul to drag around a 800# utility trailer?

 

Because Toyota recommends using tow/haul when towing. They don't stipulate that it's only for towing heavy trailers. Have you tested to see if this is the case? My 2019 would light everything without it, but 9 model years later they may have changed it.

 

Double check the fuse to make sure its good. Make sure you turn on the headlight or ensure the clearance markers on the truck are on. Now measure the voltage at the plug. It should have voltage now.

 

Rookie mistake. Checked for voltage with tow/haul on. Nothing. Pretty sure fuses are good but will check again. The number of fuses in the circuit is mind-blowing and I may have missed one.

 

There are also two different standards for wiring the lights. If the truck plug is set for one and the trailer for the other, some things won't work correctly.

 

There is a relay and 30A Tow Tail fuse that specifically control the tail light power to the connector. When you turn the headlights on the relay will close and provide power to the trailer socket. It has nothing to do with the tow haul button.

Very simple circuit. Check the 30A Tow Tail fuse in the engine fuse box. Also make sure you have a relay in there.

You are using the round 7 spade trailer light connector right?

 

Boy do I have egg on my face. Gonna blame it on being an old fart!! In addition to checking the wrong 30A fuse I also misread the wiring diagram. After re-checking for a bad fuse, found the 30A Tow/Tail fuse blown. No idea what could have drawn that much current but will chase that another day. For now at least, I have power to the connector on the truck. Thanks for all the help.

 

Glad you got it figured! We all mess up or misread stuff, but that doesn't stop the community here from helping. You may catch some friendly jabs over it, but we help if we can.

Welcome to the forum!

 

Great to hear it is fixed and wasn't to much of a pain in the ass. This forum is a great place to learn and share knowledge and trust me we ALL make silly mistakes sometimes.

I could easily believe rain/moisture can get into the trailer wiring socket and cause the fuse to blow. Anytime you turn the headlights/taillights on you are putting power to that trailer connector no matter if a trailer is connected or not.

 

Well, it was definitely wet when I was hooking up and like a dummy I failed to turn the lights on the truck off before attempting to connect the trailer. Thanks again for all the tips. Maybe someday I can return the favor.

 

Even if you can't, stick around for the banter. But we need pics of your truck.

 

LOL. Believe it or not, I have never taken a picture of it. Just a plain jane crewmax SR-5 in pyrite-mica with a rusted out bed. Do have pics of my '71 goat tho.

 

Pictures of the goat would be nice! Truck photos can be homework for another day.

 

Best thing about these forums is you have already returned the favor. One day, maybe tomorrow, maybe in two years someone else will read this thread and fix theirs also.

Had you not asked in the first place someone else would miss out eventually.

This board is such a great place to share and learn from community members. All questions, ideas, ect welcome no matter how simple.

Welcome to the site, also in to see pictures of your ride. Pictures always make threads better!

 

Not a tundra but definitely more fun to drive!

 

My utility trailer has a "gremlin" that shows up every spring - trailer lights are intermittent until I tow it for a mile or two. Then they work until I park it in the fall. I know it is a trailer ground issue. I have just been too lazy - energy conservation mode - to fix it because, it kind of fixes itself. LOL

 

B-E-A-U-T-I-F-U-L !

 

Grounds are the eternal gremlins. Boat trailers are the worse especially around salt water.