, I assume it was the amber TPMS Warning Light...
View attachment 2396352626
...that was flashing...?
My 2021 Trailhawk's Owner's Manual refers to that as the "low tire pressure telltale" when it illuminates to alert you when one (or more) of tires has low pressure.
But that light apparently has another function, as a "TPMS malfunction indicator":
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate when
the system is not operating properly. The TPMS
malfunction indicator is combined with the low
tire pressure telltale. When the system detects
a malfunction, the telltale will flash for
approximately one minute and then remain
continuously illuminated. This sequence will
continue upon subsequent vehicle start-ups as
long as the malfunction exists. When the
malfunction indicator is illuminated, the system
may not be able to detect or signal low tire
pressure as intended. TPMS malfunctions may
occur for a variety of reasons, including the
installation of replacement or alternate tires or
wheels on the vehicle that prevent the TPMS
from functioning properly. Always check the
TPMS malfunction telltale after replacing one or
more tires or wheels on your vehicle to ensure
that the replacement or alternate tires and
wheels allow the TPMS to continue to function
Is that what your TPMS light was doing?
I would expect, if one of the TPMS sensors died, that the rest of the system would still function -- that is, still show the pressure of the other three tires. But maybe not, from what jeff1
wrote -- maybe the entire TPMS system just shuts down...
If one of the TPMS sensors is dead, a good tire shop should be able to determine that with a hand-held diagnostic tool that "pings" each tire to detect whether it's transmitting and at what strength. It's a finicky process, because the TPMS sensors transmit such weak signals. The tool would look something like this:
View attachment 2396352627
I'd be surprised if a TPMS sensor's battery went dead after only three years or so; my experience is that those batteries (they're button- or coin-type batteries sealed inside the sensors) have a life span much longer than that.
But in any case, you should still replace that old vehicle battery...
the tires with a hand-held sensor that directly reads how