01 Access Cab Trailer lights wiring?

I have an 01 Tundra SR5/AC, came to me with one of those after-market, plug and play trailer wiring harnesses, but it wasn't working.. It was older so I assumed the converter box was blown... so I bought a new one (Specifically the

$51 CURT 55378 Vehicle-Side Custom 4-Pin Trailer Wiring Harness, Fits Select Toyota Tundra , Black

CURT 55378 Vehicle-Side Custom 4-Pin Trailer Wiring Harness), plugged everything in (including the connection to the battery)... but still nothing. I've checked every fuse in the truck, all of the truck's brake and signal lights work normally, confirmed 12v where it connects the battery to the truck's harness in the engine compartment, but I don't seem to be getting any power to the trucks harness where the curt converter box plugs in under the bed (back drivers side)? What am I missing... Truck is rust free (no indication of any bad grounds), no signs of any wiring issues or previous hack jobs, no sign of any rodents chewing any wires or anything?

 

Have you checked out your trailer converter box behind driver side rear combination light(backup, turn signal, tail light) if you have one or checked the 11 pin T 9 connector under the bed in that same location.

 

Uh... I don't seem to have one of those... ?

 

Early models did not come standard with any kind of trailer harness setup. Adding a converter was required. Even my 2000 Limited with all the options (laughable) did not come with a hitch or harness. I added both, used the Curt box similar to yours but circa 2006. There’s a series of connectors under the bed back there that send the signals out to the tail lamps. Run those wires and make sure there’s nothing unhooked or corroded or broken

 

My apologies in advance for any dumb questions... I hate messing with vehicle wiring, I normally don't normally mess with wiring beyond replacing the stereo head unit...
but I thought the curt thing I bought was the converter?

 

Same for my 2000 as well. I had to buy a bunch of stuff from Etrailer to make it plug n play…well most everything was plug n play. I did have to route and crimp my own 2 conductor wire for the trailer brakes.

 

It should be what you need

 

Any details or part numbers you needed? I don't need any trailer brakes, just trying to get the lights working

 

Have you tested the output of the new harness once installed?

 

OK I think I found at least some more info... the folks at etrailer say that this center connection/black wire on the truck's connection should be 12v constant, but I'm getting nothing. Anyone have a wiring diagram that shows where that wire is coming from?

 

That is the T 9 Trailer Converter connector. The black wire should indeed have 12vdc. That black wire goes up to the engine bay to a 1 pin Option Connector O 3 which is beside the battery. The Curt harness has a inline fuse that was tied to positive of battery. That conductor plugs into the O 3 Option Connector. Check that fuse and/or O 3 connector.

If that fuse is good, connection to batt is tight and Curt connector plugged into O 3 good, the next place it could be missing is the I 4 connector at the drivers kick panel. Panel by parking brake.

 

I checked fuse that came with the Curt, and confirmed 12v where that plugs into the truck's harness in the engine compartment... Do you have any more info on that I4 connector is that a fuse or what should that look like?

 

I meant to type IA4 and it is a 26 pin white connector behind drivers kick panel, big and kind of hard to miss. The 12vdc from O 3 connector goes to the IA4 connector pin 21 and is a black conductor also.

The below is my 04 DC LTD kick panel area and simply showing you for reference about where your IA4 is, which is where my IA6 is.

If it's leaving IA4 pin 21 with 12vdc, the next stop before it heads to the back is a 12 pin connector BB1 that's under the drivers seat. Pin 1 of that connector is where the O3 12vdc should be.

 

Awesome thanks...will check those this afternoon