2005 TMPS Problem w/ "Spare Low Pressure"

2005 Liberty Limited here w/ the "dumb" (or base) TPMS system ...

So I started getting the "Check TPM System" on the EVIC w/ the Tire Light steady on the dash. I figured at 16-yrs old, one (or more) of the sensors took a dump. So, I replaced all five (5) with new DENSO 550-3008 sensors.

Afterwards, I did the test drive per the FSM ....

Drive vehicle for a minimum of five minutes while maintaining a continuous speed above 20 mph (32 km/h). During this time the system will learn the new sensor ID code and will clear any DTC’s automatically.

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My "Check TPM System" warning is now gone & the system successfully "learned" all of the new sensors "except" the spare (I think). Now, at start up, I get a "Spare Low Pressure" on the EVIC & the tire light flashes on the dash ... all goes away after a minute, but comes back at each start-up (annoying). The spare "does not" have low pressure; in-fact, it has 3-4psi "greater" than the road tires.

The FSM says ...

The battery operated tire pressure sensors lay dormant (Park Mode), then wake and start transmitting (Drive Mode) when the vehicle first reaches speeds over 20 mph (32 km/h). Once the wheels stop rotating for a period of approximately 20 minutes, the sensors shut down until again awaken. Although not transmitting as when in Drive Mode, while in Park Mode, the sensors still transmit approximately once every 13 hours to let the receiver know air pressure status at that time.

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So, if I understand it correctly, the system doesn't know what's going on with the spare because "its not rotating at a speed over 20 mph" and is likely in a "dormant" state. So, I thought that maybe after the 13-hr span, the spare sensor would send it's signal & all would be right with the world again ... no dice.

I've read several posts, and I find no reported solution. Putting the spare temporarily "in action" doesn't seem to be a fix either per other folks experience.

So what the heck do you have to do to get the spare to communicate and stop the annoying "Spare Low Pressure" warning??

Easy fix. The self learn function only works on the 4 road wheels - not the spare tire ID. Every ‘decent’ scanner has the facility to code the spare tire ID.

I recently had a similar problem. Only one good sensor. Got new tires and sensors and moved the good one to the spare position. The new sensors all registered after a drive as they should. Spare still read low. I moved the spare inside the cargo area and it was picked up in there. I then moved it back outside and it is still OK with no spare tire low pressure warning. My guess is the battery is weak and it was having trouble reading it on the gate.

I still don't know how it reads each tire location. Must have antennas in various positions?