Pulls to right when I brake, what to check?

Make sure it’s not just pronounced pull due to roadway crown.
If you can replicate the same run, no trailer brakes connected that will help lpoint you in the right direction. Gravel test is good too, see if wheels aren’t braking as well.

First adjust the trailer brakes and try again.

If you need an excuse to get a DC clamp-on ammeter this is it. Apply the trailer brakes manually and see if you get about 3 amps to each wheel.

Less than 3 amps you need to trace the wire for an open connection.
3 amps and the electrical is good so you need to pull the drums and inspect the mechanical parts.
More than 3 amps is probably a short inside the drum.

Take trailer to a gravel lot.

Have someone walk along back of trailer as you slowly apply trailer brakes with manual over ride until the brakes lock.

See if both sides lock at same time or if one side does not lock.

Then you will know which wheel is having the problem.

I bet you will find grease on at least one brake or a broken brake wire.

If you have a Prodigy P3 you can check current draw. You should get about 1 amp for each volt applied if all 4 brake magnets are working.

Thanks for all the suggestions. I'll jack up the HTT this weekend, spin the tires, test the brakes, and look around. It sounds like the issue could be with the *left* side (driver side) has the issue.

To clarify (for some), my *TRUCK* brakes are fine. I only experience pulling to the right when towing.

Sounds like only one side on the TT is braking. The left side. This forces the TT tongue to the left and makes your truck nose to the right. I have had this.

Check for broken wire, or maybe a magnet is not working.

How did you check the truck does not pull? I have had stuck calipers/pistons and the vehicle would stop normal in light to moderate braking. But in a hard stop it would pull hard. Could be the extra weight of the trailer unmasking an issue in the tow vehicle braking.

You can check to make sure all the brakes are operating - one person listening close to the wheel while another operates the brake controller manually. There should be a click as they're operated. If one's not working, it's probably wiring.

Next would be to check the brake adjustment, that requires lifting the wheels one at a time and a bit more work/skill. Finally, pull the wheels and drums and look for greasy brakes.

time to call a mobil tech, he,ll come to you and figure this out, cheaper, faster, and smarter than most dealer so called mech.take it to a dealer ? he,ll sub it out to $1.98 mech.

The reading comprehension in this thread so far is so bad, you'd almost think they're trolling you...

Correct me if I'm wrong and I will eat those words, but according to the OP, the *TV* brakes were replaced ~2000 miles ago:

I verified that my TV does not pull when braking by itself. I had brakes replaced less than 2000 miles ago.

Yes, if the TV does *NOT* pull on its own then the problem is the trailer. If it is pulling to the right, then the left brakes on the trailer are probably not working.

The 7 pin connector has one wire for all the brakes. If any brakes work, then it cannot possibly be the connector.

The only thing you can see by crawling under is the wiring, if it is obviously broken somewhere out in the open. If it is broken inside a tube somewhere you are not going to be able to see that.

Jack up the trailer, spin each wheel, and get a helper to manually apply the brake from the truck. The brakes are not working on the wheels that do not stop when the manual brake is applied.

If multiple wheels do not work, suspect a broken wire first. The quickest way to resolve is to just run a all new wiring from the 7 pin connector to the brakes. You can try to find the broken wire and patch/splice it, but it will break again.

Most likely both brakes on the left side do not work but the right-siders do, the break in the wire is somewhere between where it splits to go to each side, and the brakes on the left side.