Service TPMS light staying on no matter what - Page 2 - JeepForum.com
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post #16 of 20 Old 01-22-2020, 08:58 AM
GPSBob
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How does the system know which wheel each sensor is at?

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post #17 of 20 Old 01-22-2020, 09:53 AM
ColdCase
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Post 10 has this explanation:

“ The TPM uses information transmitted from each of the wheel sensors as well as the difference in the strength of the signal received to determine the location of each of the sensors. Its the so called WAL protocol.

The information transmitted are samples from a dual-axis accelerometer in the sensor, which determines the right/left position of the tire monitor in response to a forward acceleration. The front/rear position of the transmitting tire monitor is detected by the signal strength of the transmission.

This is why the sensors are actually more complex than the receiver, and why the cheap or aftermarket sensors often don't work correctly.... and interference can affect performance.”

The tire sensor has at least three types of sensors built in, pressure, temperature, acceleration/rotation.

So one failure mode is when the acceleration sensor fails, you get pressure readings but the TPMS doesn’t know where the sensor is locate for sure. It uses the last known location for the ID and sets the fault code. In this case some hand held wheel sensor with show good as they don’t check all the data, just if the tire sensor can transmit and the ID.

To have a better idea, one hooks up a OBD scanner that can read the sensor data stored (not just the ID). May not help, but would eliminated a few possibilities. The OP’s dealer should have done this, dunno. If so, then you are into signal strength, interference, harness damage, or a bad replacement part situation.. or one of those nasty intermittents. But the simple thing first is to reset (disconnect battery, temporarily increase tire pressure to well beyond trigger points)
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post #18 of 20 Old 01-22-2020, 11:54 AM
GPSBob
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Interesting. Sorry I missed that in the earlier post. Amazing that the wheel sensors are so sophisticated. Thanks.
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post #19 of 20 Old 01-22-2020, 01:02 PM
tom19511
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Does the spare have a sensor in it?

Tom

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post #20 of 20 Old 01-22-2020, 09:02 PM
ColdCase
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Documentation is inconsistent so can’t guaranty it, but most WK2s don’t monitor the spare. There is some mention that the base system monitors the donut spare in some, but dunno.

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