Tire rotation-pressure sensor issue

[TerryP]

Changed the oil in my RAM 1500 EcoDiesel today, and per the maintenance schedule, I rotated the tires. Since my spare is the same as the other wheels, I included the spare in the rotation, using what is called the Forward Cross Pattern.

(Meanwhile, while writing this post, I notice that I should have used the rearward cross pattern--OK, maybe tomorrow). I adjusted the tire pressures to meet spec, except kept the new spare (the previous R-front tire) at its original pressure. Started the car up to check for oil leaks and, whatever, and, checking tire pressure, noticed that the spare was now identified (by its pressure--a bit higher than the others) as the R-rear tire. I conclude that there is a pressure transmitter in each tire, and that the sensor in the previous R-front tire is now talking to the antenna for the R-rear tire. Meanwhile, the (original) spare either has no transmitter, or, is overwhelmed by the signal from the new spare.

So, the question. Has anyone else experienced this problem? Is there a way to resolve it? Will the dealer cough up a new sensor for the spare? (It'd be nice if they'd paint the spare wheel to match the other wheels .

 

[John]

The matching full size spare wheel and tire assembly (if
equipped) has a TPM sensor. The full size spare can be
used in place of any of the four road tires. A spare with a
pressure below the low-pressure limit will not cause the
“Tire Pressure Monitoring Telltale Light” to illuminate or
the chime to sound while it is stored in the spare tire
location.

After driving the vehicle for up to 20 minutes above
15 mph (25 km/h) the “Tire Pressure Monitoring
Telltale Light” will turn OFF and the pressure value
will be updated and return to it’s original color, as long
as no tire pressure is below the low-pressure warning
limit in any of the four active road tires.

 

[TerryP]

Thanks, John

It looks like the system is a bit more complicated that I believed. However, now I'm even more confused. Yesterday I redid the rotation so that I ended up with the rearward cross, which was recommended for rear wheel and 4WD vehicles. This required swapping the two front wheels, and the spare and the L-rear tires. Then we drove into town, and, to my surprise the tire inflation alarm was illuminated. So, I used the system to see the reported tire pressures. After cool-down, the results were:

-- 40
41 41

indicating no pressure in the L-front tire. However, it was inflated identically to the other tires. I don't know what's going on. Obviously, the L-front tire result is not correct. The original L-front tire is now the spare and the new L-front tire used to be the L-rear tire. Puzzling to me.

Tomorrow, I'll drag out the air compressore so that I can unequivocally see which tires pressure is indicated by the RAM computer system.

Should be interesting.

 

[jdn112011]

My guess would be the spare doesn't have a tpms, I've never had a single issue rotating tires or ever needed sensors reset, and we're talking about going on 8-9 rotations in it's life? But only ever a 4 Tire rotate. Different patterns have not mattered