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Not sure, but I think early C7s maybe had the K65 Tire Pressure Indicator Module, but newer ones certainly don't. This is perhaps another one of the errors I have found in the Factory Service Manual. In pictures I have seen of what is behind the rear bumper cover, there is no K65 module.
In newer C7s, the signal from the Tire Pressure sensors (in the tires) is received by the RCDLR (Remote Control Door Lock Receiver), and then the digital data from each sensor is sent to the BCM module, over a CAN bus.
The RCDLR is located on the back-wall of the rear cargo compartment, on the interior, covered by the rear trim panel. The RCDLR talks to the BCM (thru a CAN bus), sending it the sensor ID#, the tire pressure, and the sensor battery status. The BCM then determines if the TPMS system is operating correctly (The BCM checks if each sensor transmits to the RCDLR ever-so-often if it detects that the wheels are turning), and sends the tire pressure info to the Instrument Cluster for display.
The RCDLR uses the 6 antennas so it can locate where the key-fob is (outside the car, or inside the car), and the 6 antennas are also used to pick-up the TPMS signals, perhaps aiding the TPMS system to identifying which wheel is transmitting from what location.
I think the problem is either a bad antenna, or a poor connection to an antenna, OR the RCDLR itself has an internal problem. My plan is to first check the connectors at the RCDLR, to see if there is any corrosion / oxidation of the connectors which go to the antennas. But, my car is now in storage, this will have to wait till springtime 2026.
Mine is an early C7 (Born in November 2013) so I likely have the K65 receiver. GM Parts lists the P/N 22923527 as valid for my car VIN. It is an 1LT, without the additional boom box speaker in the rear
So.... what do I need to disassemble to replace it? I think this is the next step in troubleshooting.
I have already tried multiple TPMS transmitters (my tire shop was very generous and replaced it twice) and when I swap tires from side to side, the Passenger Front still faults.
I think the problem is either a bad antenna, or a poor connection to an antenna, OR the RCDLR itself has an internal problem. My plan is to first check the connectors at the RCDLR, to see if there is any corrosion / oxidation of the connectors which go to the antennas.
I am also having similar problems.
Last month I purchased a 2015 Z51. I drove the car home almost 200 miles with no TPMS problems. A week later at the exact same time/distance into my drive to work, I get the Tire Pressure Monitor message and the amber TPMS light blinks several times and stays on. It shows no number or input from the right front wheel.
I did install LED side marker lights after I got the car home from the dealership BUT.. I've tried using foil tape and also nothing on them to see if that may have been the issue. I had these same lights on my 2014 I recently traded in and never had an issue with TPMS. At this point I'm doubting it's the side marker lights but I haven't ruled it out. I'm still planning to drive it the same distance or farther after disconnecting the right front light to help eliminate that as a cause.
I'm also wondering if it's something more than the sensor or the batteries in it failing. On the carfax for my car, in 2019 a dealership serviced the car and it's documented they replaced the BCM. 10k miles when that was done. Only has 35k miles now. That has me curious as well. I have reached out to them to see if they will elaborate on what the symptoms were back then.
