Replacement trailer wiring harness - Toyota Tundra Forums : Tundra Solutions Forum

Exsys · #1 (**permalink**) 03-15-2007, 10:06 PM

I have an 04 Sequoia and when I bought it the hitch was wired with a harness for the 4 wire trailer plug. 2 of the pins were ripped out by the previous owner. I bought a replacement plug to spice into the damaged harness so I could tow until I got it fixed. When I got under the truck it was very interesting to see how it was connected. The wiring for the 4 wire harness was plugged into a 4 pole plug under the driver side of the vehicle. Right next to that is another 3 pole plug that is capped off and has very heavy gauge wires connected to it. They appear to be about 10 gauge. My assumption is that these two plugs can be connected to a different harness for a factory 7 wire harness and plug. Does anyone know if this is correct? Does anyone have a part number and price for this harness? Thanks in advance.

DCTUNDRA · #2 (**permalink**) 03-21-2007, 01:56 PM

I believe your assumption is correct. However, just plugging in the proper harness may or may not enable all the functions. You would need to determine if the proper fuses and relays are in place. Later model Ford truck have the same wiring harness and they just leave out the fuses & relays for trucks without the towing package. In any case, having the wires already run should make wiring up a 7-pin connector much easirer. You might want to check out the website Trailer hitch, hitches and bike rack (800)298-8924 to see what some of the connector and harness kits look like to do exactly that on GM, Ford, & Dodge trucks. They also make generic kits to allow you to splice directly to thos 2 wiring harnesses you have discovered. Also, you could phone the etrailer folks or go to your local Toyota dealer and purchase exactly what you need. I discovered that the Ford dealer sells replacement 7-pin harness asemblies for less than the aftermarket a short while ago. Lastly, there is always the junkyard (excuuuusssseee me - in Steve Martin voice, automotive recycling center) to see if you can find the parts you want.

Exsys · #3 (**permalink**) 03-27-2007, 09:46 PM

I finally found what I was looking for. There is an awesome trailer plug that is an aftermarket with a clean connection to the Toyota factory plugs. It is called Hoppy Multi-tow and the part no. is HY43385. This handy little unit plugs directly into the 4 wire and 3 wire plugs under the Tundra and Sequoia rear to give you a 7 blade (not pin) female receptacle AND a 4 pin vehicle side connector next to it. So you get the best of both worlds without any splicing and no adapters to lose. A web search reveals the price to be $39.99 with free shipping on ebay in the stores section, $33.99 at hitches4less.com with free shipping but it is also available at northerntool.com for $24.99 with $5.12 shipping. It is part no. 633385 at northerntool.com. Wonderful device. Better than I was expecting because I wanted the 7 pole connection for my trailer with an electric tongue jack and I may mount a winch to it but now I can also tow trailers with 4 wire connectors. I am going to order mine today.

shall36 · #4 (**permalink**) 03-28-2007, 08:53 AM

Unless you have the Tow package on your rig, the 3 additional legs will not be functional. I went through this on my Tundra. The wiring for the electric brake, power (charge) and reverse is missing from the engine bay fuse box back. The Sequoia may be different. Open up the fuse box in the engine bay and see if you have the fuses and relays for the tow stuff. If the stuff is missing, check to see if the wiring is present. On the tundra, the fuse box has a spot for the fuses and relays, but no wiring.

Exsys · #5 (**permalink**) 03-28-2007, 11:35 AM

Mine did come with the tow package from the factory but it was only wired for the 4 wire setup. I will check to see if it has the relays and fuses. This would be the box under the hood, correct?

Exsys · #6 (**permalink**) 03-28-2007, 11:44 AM

Mine did come with the tow package from the factory but it was only wired for the 4 wire setup. I will check to see if it has the relays and fuses. This would be the box under the hood, correct?

shall36 · #7 (**permalink**) 03-28-2007, 12:38 PM

There are two different tow packages...one has the 7-pin connector, trans cooler, and HD alternator. The other just has the receiver and 4-pin connector. My truck had distributor installed hitch with connector. I think that was package DH. The full-blown package was code TO.

Exsys · #8 (**permalink**) 03-28-2007, 01:28 PM

I do have a transmission cooler but it could be just because it is the Sequoia.

I checked the fuse box under the hood and all fuses are there for the trailer wiring. There is 1 missing relay but the terminals are there for it. I will see if I can get the relay and make it work.

dellgeek · #9 (**permalink**) 04-04-2007, 05:15 PM

I have a similar situation. My truck (2003 Tundra) came with the poor man's towing package (hitch and 4 pin flat connector). Recently the pins in the connector fell apart. I search the forum and came up with this part number for a replacement harness 08921-34850 ('02 Tundra). I ordered this part hoping it would fit my truck but it doesn't. I am now looking for the correct part number and I spent 30 minutes at the parts counter of my local dealer. We came up with 82169-34020, but the description states "WIRE, FRAME, NO.3". The picture on the parts diagram was very hard to tell, but it looked similar to my harness. Anyone know if this is the correct part number or can look it up?