Join Date: Sep 2017
Own a Commander?: Yes
Model year: 2006
Trim Package: Limited
Power-Train: 5.7L V-8 Hemi
If 4WD - system: QD-II
Current Mileage: 112000
Drove it plenty to do the reset. Found some related info that may help point in a different direction. Apparently the XK system is the same as used on the Grand Cherokee as well as the 300 Chrysler. Info on those forums have a lot of TPMS complaints just like I have read here. On a 300 forum, I found the following info that I have not seen in the XK service manual
"On vehicles equipped with the premium TPM system, the Wireless Control Module (WCM), commonly referred to as
the Sentry Key Remote Entry Module (SKREEM), uses transponders (trigger modules) located in three of the four
wheel wells on the vehicle to provide it with the location of the tire pressure sensors on the vehicle. Like the base
system, the WCM receives RF signals from all four rotating wheel speed sensors. When the WCM needs to know
which sensor is located at a particular location on the vehicle, it directs the transponder at that location to send out
a low frequency signal to excite the nearby sensor. The WCM then receives that excited signal and knows where
that sensor is located. This auto-locating process only happens in the first 10 minutes of any WCM cycle while
traveling at speeds above 20 mph (32 km/h) (Each WCM cycle ends when the vehicle has been shut off for a time
period of approximately 15 minutes or longer). Once the WCM has performed this to the three locations that have
transponders (left front, right front and right rear wheel wells), it uses the process-of-elimination theory to know that
the fourth sensor ID signal is coming from the left rear tire sensor."
I had been assuming that the three transponder modules were reading the tire info but that is not correct per this info. The key ingredient is the WCM. It tells each transponder to (in turn) tell its tire sensor to broadcast its info. Based on the timing for these events, the WCM knows which tire is where and its info. Although the left tire is transmitting periodically, the WCM never tells the left rear tire when to transmit so the WCM reads the unknown tire info as the left rear tire by default. I don't know how the spare fits in here.
If this is correct, the problem child here is the WCM - not the tire sensors or the three transponders. Appears that the WCM is failing to read or use the info it is receiving from the left rear (or the spare?) This suggest that the problem (in my case) is that the WCM is not reading (or interpreting) the signal for the left rear tire.
Not sure how to test this theory. The WCM also receives the signals from your key fob so it may not be a generic box that can be moved from one vehicle to another (such as from a salvage vehicle). May require a dealer to program it. I also assume it is not cheap. Going to visit local dealer and see what they say.
06 Limited, 5.7L, 4x4, Light Khaki
89 Grand Wagoneer - everything works