JMckinney

I recently purchased a used 2013 2 door jk. It had 33's and a small spacer lift on it. Changed that to something much better. Also, I just put new 15" wheels and 35's on it yesterday and had the tire guy put 30psi in the tires. I took the 5 wheels/tires home and mounted them on. Went for a drive and noticed I didn't have the tpms light or any alarms on. Is that normal for 30psi in that size of tire? Or did previous owner turn that off? I was going to get a flashcal or something to flash the ecm for the tire size change and for the tpms light but I'm thinking now that stuff was changed already for the 33's that were on it. So will I be able to change anything without the programmer the last owner used? Sorry for the long post.

JMckinney

Actually the psi doesn't matter due to because I didn't have tpms installed. So I should have a light on at the very least. I just want to change the tire size so my speedometer and odometer are correct. Just don't know if I can since someone else may have used a programmer that did not come with the jeep.

Billbikes

How long did you drive with the new tires? Sometimes it takes a little while for the TPMS to pick it up.

14Sport

You should still be able to use the programmer. However, what is set right now will be what your programmer will think is stock. So if you make changes, and then need to run the return to stock option later, it will come back to where it is right now. My programmer thinks my 4.56s are stock because that is what I had the gears set to when I got my flashcal.

JMckinney

Ok so if I plug in a new tuner the ecm will allow changes to be made even if it doesn't recognize the new tuner. I've heard that the tuner is married to the vin stored in the ecm. I was also told just didn't know how true it was that I would have to go to the dealer to have the ecm flashed back to stock. That would probably cost a few hundred then I could get a tuner and make my changes.

14Sport

It's the tuner and not the ECM that is the restriction. If you buy a new tuner and make any changes to your Jeep with it, it is now "married" to your VIN. The only way to "unmarry" it is to use it to return to stock. If you get a dealer reflash without "unmarrying" your tuner then your tuner will no longer recognize your Jeep and be locked. So before you bring it to the dealer for a recall or whatever that requires a reflash you need to unmarry your tuner (return to stock) so you can use it to reset all your stuff when you get it back. For example, if you have regeared and used your tuner to set the gear ratio so you don't go into limp mode, then you should reset the Jeep to stock at the dealer with your tuner and then when they're done reset your gear ratio back to what you're running before you leave. Otherwise you will go back into limp mode. Not that limp mode is the end of the world. You can limp (stuck in third gear for an auto) home and reset it there.

JMckinney

I see.. so I should be ok with getting a tuner and making my adjustments since I'm going up in tire size. But I wouldn't be able to go back to stock since those changes were made from someone else's tuner. I could only go back to what it is now and that is what the computer thinks is stock.

14Sport

Yes. Well that is what the tuner thinks is stock.

JMckinney

Thank you👍

14Sport

You're welcome, J.