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Discussion Starter #1
I have a 2015 Tundra CrewMax with the tow package that I pull my boat trailer with. When i back up my boat trailer, my surge brakes lock up. The boat trailer has a back up trailer solenoid that is supposed to activate I put my truck in reverse and this is supposed to keep my trailer brakes from locking up during reverse. However, i have no power on my center pin and i need help on how to troubleshoot why there is no power. I'm told that if i have power on my center pin, this should solve my problem, assuming the solenoid is not defective. Is there a specific fuse or relay that provides this power? i realize can always use a pin to lock out the surge brakes however since i am supposed to be able to back up without my brakes locking up, i would really like fix the problem so that i don't have to go through this extra step. My boat trailer has a 4 pin connection which i then convert to the round 7 pin connection. Interestingly, another trick someone told me about that works is to reverse the connection between the 4 pin and the 7 pin. when i do this and turn my truck lights on, the trailer brakes do not lock up in reverse. The problem is that i forget to put it back and then my trailer signals are reversed while i am driving. I have attached a picture of the 4 pin to 7 pin connection I'm using. I attached another picture to show what i mean when i connect them in reverse which is my workaround for backing up without boat trailer brakes locking up. Any advice ? Thanks
 

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I'm not a towing expert, but a 4 pin harness does not have a reverse light wire, but I have no idea how your adapter is wired.
Also, are you checking for power on the center pin with your truck in reverse?
 

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It's not always the center pin...

Look at the cover of the plug and it should say on it which pin is the back-up pin.

It wont be the electronic brakes pin, that's for trailers with electronic brakes. Your trailer has hydrolic brakes, and the solenoid bypass will be activated by the reverse or backup pin.

Once you identify the pin (most flat/blade style, it IS the center pin),

Make sure you're checking for power with the truck in reverse, will have to have a buddy for this.
If you're not getting power to it, check the fuse. That or a relay has usually been the culprit in my experience.

If you are getting power to the pin, then the next thing to check would be your plug on the trailer side, make sure the wires inside are secure, and power is actually getting to the solenoid.

If power is getting to it, then it could be the solenoid itself is bad...

There are a few ways to disable the brakes if you're in a bind, you can put a pin or a nut or something behind the coupler pin and keep it from being pushed back, or you can make a jumper wire to plug into the reverse blade on the trailer side, and plug it into the running lights pin on the truck side, turn on the lights, and it will bypass the solenoid.
 

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Welcome aboard from the balmy San Diego Bay Area.
 

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Discussion Starter #7
thank you for your help. it was my 7.5A fuse under the driver panel. once replaced, i have power to my center pin and my solenoid works perfectly. Thanks again!!
 
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