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Discussion Starter #1
So I have a 2002 tundra with a 4 pin lighting adapter. I am picking up a trailer that has a 7 pin plug and I need to adapt to that.

I bought the following:

Adapter 4 Pole to 7 Pole & 4 Pole 37185 : Trailer hitch bike rack and trailer hitches - etrailer.com

I plugged it into the 4 pin, of which only 3 are active as it doesn't appear to pass the ground, and then touched the ground to the truck frame.

After this I plugged in my buddies trailer that I had to test and no lights, nothing. However, when I touch the ground wire to the truck frame, I do get a spark so I know I'm getting power. What am I missing here? How can I test that I'm getting power to the 4 pin?

I figured it would be a fairly simple hook up.

Thanks in advance.
 

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So I have a 2002 tundra with a 4 pin lighting adapter. I am picking up a trailer that has a 7 pin plug and I need to adapt to that.

I bought the following:

Adapter 4 Pole to 7 Pole & 4 Pole 37185 : Trailer hitch bike rack and trailer hitches - etrailer.com

I plugged it into the 4 pin, of which only 3 are active as it doesn't appear to pass the ground, and then touched the ground to the truck frame.

After this I plugged in my buddies trailer that I had to test and no lights, nothing. However, when I touch the ground wire to the truck frame, I do get a spark so I know I'm getting power. What am I missing here? How can I test that I'm getting power to the 4 pin?

I figured it would be a fairly simple hook up.

Thanks in advance.
It indeed should have been a fairly simple hookup...not a huge amount can go wrong on 4 pin trailer connector. Your's obviously has a problem and I think you've kind of already identified the cause...the connector does not have a functioning circuit that goes to a ground on the truck.

On a 4 pin connector, one wire is tail/running, one is left turn/brake, one is right turn/brake, and the 4th (the one that's different in the plug) is the
ground. A really simple way to test the various circuits without getting involved with wiring colors (which sometimes aren't the standard colors) is
1. Go get a cheap ($1.95) test lamp at your local auto parts store.
2. Then attach the test lamp's alligator clip to a good ground on the truck (like a bumper bolt that's been cleaned up enough to get some shiny metal showing).
3. Then turn on the truck's parking lights as well as the 4way flashers...this should provide some kind of voltage at every terminal on the 4 pin connector except the ground pin.
4. Finally, stick the test lamp's probes into each of the non-ground pins on the truck's 4 pin connector...you should either get a steady light (indicating you stuck the probe into the tail/running light wire) or a flashing light (indicating you stuck the probe into one of the two turn'/brake lights.

If only 1 or 2 of these wires light up the test lamp, you'll have to do some troubleshooting....starting with the fuses in the fuse box under the hood.

If the connector passes the above tests, then all you have to do is find and fix the reason its ground doesn't actually go to ground.
 

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Hi,
I have a 2002 Seq. and ran into the EXACT same problem. I drove 4 hours away to pick up a coleman popup. I have the 4 pin setup and needed to adapt to the 7 pin. I purchased a 7 pin adapter, hooked it up and NOTHING--no lights! Kindly enough, the gentleman I made the purchase from checked with his volt meter. I did have 14 volts showing constant thorugh the 7 pin. The 4 pin did work when we hooked up to a "brake light hitch hider" and my utility trailer when I got home. What gives??

Dan
 

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Discussion Starter #4
Thanks guys :tu:

Ended up being a fuse being blown, I assume by the previous owner. :)
 

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my 00 came with a hoppy 4 wire set up, wanted a trailer brake option, found at numerous auto parts places and tractor supply was an adapter that allowed the 4 pin plug to be used on the back side, along with an external ground, trailer brake wire, and back up wire? the front side it has a 4 pin connector and a 7 pin connector. i used this option to keep from having to buy an adapter and it also keeps me from loosing the adapter. cost was @ 25.00 well worth it in my opinion.
 
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