TPMS Sensors

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2,176
Location
Flaherty, KY
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My '07 Pacifica has a tire pressure readout for each individual tire, a handy feature for sure. Well today I rotated my tires and now my tire pressure display is reading wrong, the values it shows are for the old tire position before I rotated. Is this an attribute that has to be set with a dealer scan tool? Are there inexpensive scan tools available that can perform this function? For now I just have to make a mental note which reading is which tire, not the end of the world, but it'd be nice to correct this.
 
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83
Location
Pennsylvania
There are 2 ways to retrain the TPMS on that car per the factory service manual. Option 1 involves writing the sensor IDs to the WCM with a scan tool . Option 2 is to let the vehicle go to sleep (key off/out, doors locked for over 20 minutes) then drive for 10 minutes over 15 mph and the system will self learn
 
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3,117
Location
Outer Banks, NC
Depending on the make and model, sometimes you have to drive 50 miles plus for the computer to reset and recognize the new wheel positions. On the other hand, if that fails, any tire dealer can use a tool to "reflash" each wheel for a reasonable fee.
 
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9,923
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USA
I found this:
Originally Posted by otobasic
No special tools are required to perform this relearn procedure , however a properly formatted TPMS scan tool may expedite the relearn process. Sensor Relearn Procedure without a Scan Tool : Inflate all tires to pressure listed on the placard. Let the vehicle sit OFF for a minimum of 20 minutes Drive the vehicle above 15 MPH for at least 10 minutes. The relearn may take from 10 - 35 minutes of driving . The vehicle will learn each sensor Id and turn the TPMS light off.
 
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2,176
Location
Flaherty, KY
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So it sounds like I don't need to do anything but drive for 10+ minutes and the system will adapt? I wonder how the ECU has the ability to do this-- because it really doesn't have a way of determining each sensor's physical location, does it? My thought would be it uses ABS wheel speed sensors compared to steering wheel angle perhaps. Really interested to know how they do that self-learning magic trick.
 
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269
Location
D-FW, Texas
I don't know specifics about your example, but it's possible they can use signal strength if there are individual chassis-side receivers for each tire. That, and accelerometer data could help correlate the sensor position. The drive cycle would also eliminate non-intended sensors, such as a car parked next to yours.
 
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2,176
Location
Flaherty, KY
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Seems the system did self correct itself. I didn't notice it but the tires swapped while I was driving this morning. I keep the rears a couple PSI lower than the fronts, and the lower pressure tires were displaying correctly in the rear now. I thought I was in for a major hassle having to go to a tire shop to get this resolved, glad that wasn't the case!
 
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3,922
Location
SW Ohio
So when someone goes to their tire shop for the "free" balance and rotation many offer with tire purchases or at repair shops that do oil changes + tire rotation, they have to quickly re-program the TPMS ? Or, if the vehicle has an automatic re-learn procedure that the shops just leave it alone knowing it will sort itself out in a short time ?
 
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83
Location
Pennsylvania
A TPMS system that is self-learning has a receiver in each wheel well to learn which sensor ID has the strongest signal and report that. Non-self learning systems usually have a central receiver and you tell is which sensor ID is at each position when you do a retrain. Systems that are not capable of displaying individual pressures that only have a generic low pressure warning light dont care which sensor is in which position as long as the car knows which 4 (or 5) sensors it is looking for. Those systems only need to be retrained when a sensor is replaced. TPMS sensors work on the same frequencies as keyless entry transmitters so many manufacturers use the keyless entry receiver for TPMS as well. A Chevy work truck without power locks or keyless entry still has a remote keyless entry module but its sole purpose is TPMS
 
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2,176
Location
Flaherty, KY
Thread starter
Originally Posted by JohnnyJohnson
One of the most useless accessories ever put on a car.
Why is that? I find them extremely handy. I don't walk around my car every time I hop in, and more than once the TPMS has alerted me to a low tire that I wouldn't have otherwise noticed until later. I'm not talking about the low tire from going 17 seasons without ever checking air pressure, I'm talking about the surprise you have a nail in your tire type. If they're in good working order, it's a nice feature to have. Biggest issue I see is that people neglect them, live with the dashboard light illuminated instead of replacing a $30 sensor and then problems pile up until you have a big repair bill to get it working again. I had an '00 Pontiac that used the ABS wheel speed sensors to determine if a tire was low. It couldn't tell you which tire was low, but the system was bulletproof. No wireless radio frequencies, batteries, programming or individual tire pressure sensors to mess with. I don't know why everyone didn't just go that route instead of the complicated system that's now in widespread use.
 
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