Probably is the sensor.
Not sure on a TJ, but on the JK's if you pull that wire without having the battery disconnected the whole time it'll throw an error code, light up the dash, and only the dealer can clear it with a safety-pinned code on the starscan. My guess is if it's possible move them to the new seats, if it's not possible have the dealer disable the sensor on the Jeep's computer.
I'm assuming you don't have heated seats...