Can I get it to learn without the diag tool?

My 08 jeep is yes, my son works at a tire store he says they only test drive to learn on Mopars

If you replaced it just be sure the battery was unhooked. I left Mopar in 2011 but what they did then was had the cluster as back-up for the TIPM. Both of them basically stored all the vehicle info and options and when you power the TIPM back up after being replaced it should get all the right info over the Buss circuit from the Cluster since that also stores the vehicle info. Now if you replace the cluster and TIPM at the same time then you have to go on line with the truck hooked up to Mopar and download the trucks info from Mopar by the VIN. I had to do that once when I got a Durango that was hit by lightning. Funny as I remember it took out all the Computers on the truck and all the pressure sensors like the MAP , Trans line press sensor , AC press transducer and so on. Ron

If you are referring to the tire pressure monitoring system, then it should be just driven for a certain miles above a certain speed to get it to sync. After having mine replaced it showed "--" and low tire light was on. By the time I got home, it was at "36" and low tire light was off.

Oh yes I was thinking you meant the TIPM or Totally intagrated Power Module. Forget what I said if you mean the Tire Press Monitor System as for some reason my brain was just thinking TIPM instead of TPMS as I seemed to have added the I after the T since I had the TIPM on my mind. Sorry about that if you mean the TPM system. Ron