EDIT: MISSION COMPLETED
LATER EDIT: Here's the TL/DR explanation of what I describe below. For various reasons, I wanted to have tire pressure monitoring without having to deal with those pesky sensors. And now, after some tweaking and coding, that's exactly what I have. I can swap summer and winter wheel/tire sets - neither of which has TPMS sensors - whenever I want, and my car will still alert me if one of them has low pressure.
BACKGROUND INFO: US Spec E84 models (and maybe some more recent specs for other countries) use the TPMS system that relies on individual pressure monitors in each tire. If you have metal valve stems, you have this type of TPMS. Up until very recently, most other countries use a system called FTM that relies instead on monitoring the tires via the ABS sensors. FTM basically looks to see if one tire is rotating at a higher speed than its opposite-side partner, which indicates that it has a lower level of inflation.
FTM works pretty darn well, but US regulations require TPMS in newer cars. So for some cars, like the E84, BMW just added in the TPMS system in addition to the existing FTM system. Since FTM is tied to the ABS monitors, I guess it really didn't make any sense to change the production and remove it for TPMS markets.
The upshot of this is that US-spec E84's have a sensor-based TPMS system because it's the law, AND they have a fully working sensor-less (sort of) FTM system because BMW didn't bother removing it. So my quest was to disable the TPMS system and enable FTM, which will make things much easier and less expensive when it comes to swapping wheel sets and replacing tires. Disabling TPMS would have been enough, honestly. I managed to survive the past few decades with manually checking my tire pressure. But I wanted to go the extra mile and retain the additional level of safety provided by automatic tire monitoring.
Here are the results:
After getting some help from a couple of very nice European folks I was able to figure out the coding. Full details:
***PLEASE NOTE I AM NOT RESPONSIBLE FOR ANY DAMAGE YOU DO TO YOUR VEHICLE IF YOU DECIDE TO TRY REPEATING ANY OF THIS****
1) Disable/disconnect physical TPMS RDC module. The specifics are further down in this thread, but basically it should be under the car and behind the rear axle.
2) Code OUT $2VB and ADD IN $265 in the VO.
3) Change the following codes in CIC, KOMBI, and XDSC:
CIC: RPA_CIC
aktiv
CIC: RDC
nicht_aktiv
CIC: RDC_SAFETY
nicht_aktiv
KOMBI: RDC_ALIVE
nicht_aktiv
KOMBI: MMI_ENA_RPA_RDC
aktiv
KOMBI: RDC_VERBAUT
nicht_aktiv
KOMBI: DSC_MIT_RPA_CC
aktiv
KOMBI: RDC_DISP_SWITCH
nicht_aktiv
XDSC: AUSSTATTUNG_RPA
aktiv
And that was it. Then you can go into the status menu. If you go to the Flat Tire Monitoring System tab, it should see there is an error. Just go to the 2nd tab and reset it. Then you should see green in all corners.
RPA FTM is now working on my US-spec E84.
But does it
really work?
As a test I dropped the right rear tire down from 41 to about 29 psi. I then drove for less than a mile and got this:
VERDICT: COMPLETE SUCCESS
Thanks so much to everyone who helped me out with this!
