Trailer making my SUV lock up.

Try this test: Hook up the trailer, but do NOT hook up the electric plug to the trailer. (Do this in the daytime, so lack of trailer lights will not be a big safety issue). Take the rig for a road test, preferable on the same stretch of road you used when you had the problem. See if the brakes still lock up.
If they do lock up, then problem is in the Jeep. If they do not lock up, then problem is in the trailer brake wiring setup.