I bought this Tundra several years back, used, w/o tow hall (4 pin trailer connector). At the time was only pulling a 18' aluminum boat, the 5.7 doesn't know it's back there. I just bought a real boat and need to convert to 7 pin. Is it as simple as buying the 7 pin harness and mounting hdw. from Toyota. Or am I missing something? There is an extra connector under the truck to accommodate the new harness.

The boat trailer has 7 pins? Just so I understand you correctly, your truck didn't come with a tow package?

Could you upload some pics? I have an '11...

Why do you need to convert to 7? Do you have electric trailer brakes?

https://tse1.mm.bing.net/th?&id=OIP....amp;p=0&r=0

Sorry for the confusing post,
My Tundra did not come with tow hall, it has a draw tight hitch and a flat four pin connector.
I need the receptacle the above plug fits into.
Picking up a new Skeeter ZX250 on Friday. The trailer does have brakes, but I believe that they are inertia activated, not electrical.
I found the correct wire harness that the Tundra's with tow haul use from Toyota. Part 82169 (type B).
My question was is that all I need?

Yes that is all you should need. That is exactly what my truck has. Everything should be plug n play with that part #.

How much is that Toyota part setting you back? You can get an aftermarket for about $15 without the wire harness. If not using or planning to use electric trailer brakes you can cut off your 4 pin and and hook up the 4 wires to the new female plug at truck. Of course this only works if you only need stop, turn and running lights. Toyota wanted $200 plus for the part when I had to replace the 7 pin on my 2009.

Is the plug on your new boat a flat 5 or round? I have never seen a bas boat with a 7 pin.

If this works it will be a lot less than the socket and wire from Toyota. http://www.easternmarine.com/4-flat-vehicle-to-7-rv-blade-trailer-adapter-47205

Seven pin connectors are a tricky beast, but so nice to have backup lights and a battery charger for the towed vehicle.

"back up lights" this is why I need the conversion. The inertia activated brakes on the trailer would be applied while driving in reverse, so when you put the truck in reverse, the trailer brakes are deactivated. This is how I understand the inertia brake system on the new Skeeter trailer. Please correct me if I'm wrong.

You should just need a flat 5 pin. The 5th pin is revers light.

That doesn't work. He needs FIVE circuits (left, right, tail, reverse, ground). The fifth circuit added over what he has been using is the reverse. It's not there just to turn on back-up lights on the trailer. His brakes will be disc, and they are so efficient that when backing up, they must be disabled or component damage will occur due to binding and excessive pressure. The "reverse" circuit typically energizes a solenoid that disables the brakes, so it's very important even if the trailer doesn't have any back-up lights.

He is correct that it is very important that he make some change so that his reverse circuit is available to the trailer - if he ever intends to back it up!

I don't know why they would be tricky. A trailer only picks up the circuits it needs. The rest of the contact bays are empty on the trailer side. As for back-up lights, the reverse circuit isn't an option on any modern trailer with disc brakes (and most boat trailer brakes today are). It's mandatory for energizing the brake lock-out solenoid when the trailer will be backed. Having the option for back-up lights is actually secondary.

Tricky because there are optional wiring schematics. One wire moves around according to your setup. New truck had 7 wire so I had to convert my trailers. Tricky.