I think you are confused. TPMS and Tire Fill Alert are two different systems. The TPMS is active all the time. It has nothing to do with the "Tire Fill Alert" feature which is for filling a tire after a warning has been established. With it off at the screen, let air out of one tire below the low pressure alert setting. Then drive it a bit to trigger a tire pressure warning. Once a warning has been established, the "Tire Fill Alert" when active uses the TPMS signal.
I have a 2021 Laramie (UConnect 4) and today was the second time I tried using the Tire Fill Alert. Doesn't work as well as it should. On the screen it is always "active" but as I read on other post, the UConnect screen reads "Assist". The fill alert only seems to work if an alert was sent because of one tire being below 30PSI and only alerts for that one tire. This morning the temps dropped to 57º in Central Florida. yesterday It was 83º. My truck did signal that the tire reached the correct pressure. I checked and my gauge and the screen both read 38 PSI. It should be 36. I did a rear tire that was at 32/ Low pressure is below 30PSI. I filled it and nothing happen. The screen read 39 PSI. With a gauge I set all tires to 36PSI.
The 2021 manual reads that the "hazard lights" will be on when the "Tire Fill Assist is active"? What hazard lights?
I'm find discrepancies all the time in most instruction or owners manuals. Writers for these manual's are usually not engineers, software developers nor mechanics. They read the specifications from the first released specification requirements. As things are developed small changes occurs and at times the writers are not aware of them. Once the final draft is completed, the product may not be reviewed by engineering or software development. In your case something changed to deactivate the feature and since it is used only to fill a tire, there could have been a software change or an over site (error).
Yes! I understand the difference between TPMS and Tire Fill Alert. I also understand STPMS (Select Tire Pressure Monitor System) and believe this was an added feature with the new UConnect5 System. (Not sure if it was available on UConnect4).
With the UConnect5 System I can select the Tire Pressure (STPMS) I wish to run in my tires. (In my case I took the factory tires/wheels off and replaced them with a different set up) Instead of running factory 60psi Front and 65psi Rear I choose to run 55psi all the way around because I don't usually carry a load and want a smoother ride.
I never go by tire pressures on the nomenclature plate attached to the Door Frame (or other location) because different tire manufactures require different amounts of air in their tires based on the way the tire is built and their handling characteristics, IE, 6Ply, 8Py, 10Ply, etc. Its always safer to go by the psi rating on the side of the tire and you also get the best tire wear by not over or under inflating. Hint! Look up Tire Pressure Chalk Test on the internet. It shows you how to get the perfect tire pressure for the tire once mounted on your truck to get the best tire wear.
As I understand where the hazard lights come in to play, when you are in the "Tire Fill Alert" function, as you inflate a tire the "Hazard Lights" begin flashing once the tire reaches the selected psi. On the UConnect 5 System your horn will chirp twice to notify you have reached the selected psi for that tire. If I recall the "Hazard Lights" flash as well.
My system worked flawlessly for 10 months so I'm sure the software programmers fixed one bug and didn't test the system to see if it broke another area. We are essentially the Beta Testers for Chrysler.
It's also sad to hear they've never worked out the bugs in the UConnect4 System which tells me UConnect5 will be just as buggy as UConnect4. When you pay $65-$100K for a truck it should work flawlessly.
Many manufactures are adding functions to their monitoring systems that will only work if you have a monthly paid subscription. I'm sure Chrysler is monitoring the importance of each function so as to understand what features are most important to their customers so they can eventually charge a monthly fee for those features. Trust me! It's on the horizon.......