Tire Pressure Monitoring System warning (false alarm?)
01-04-2008, 04:25 AM
#1
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Tire Pressure Monitoring System warning (false alarm?)
Took delivery of new TT yesterday and on the way home a yellow warning icon for TPMS appeared on the dash. We considered turning around and going back to the dealership, but it was getting late and I thought one of the tires might be low. Get home, one front tire is 1 PSI too low (is this thing really that sensitive???) so I pump it up and all tires are now up to spec according to the label inside the driver side door. I hold down the TPMS button for 5 seconds (per manual) to reset the baseline air pressure, turn off the car, and all seems fine. Turn it on and off a couple times (without driving) for good measure, so far so good. Go no less than 100 yards this morning and the warning icon appears again!
Is it already time to go back to the dealership for my first "repair?"
One possible clue (cause?). At the dealership, we exchanged the black plastic valve stem caps for some nicer silver metal ones. Does the TPMS system rely on some sensor embedded in the plastic ones (they looked like the regular cheap plastic ones to me)?
Is it already time to go back to the dealership for my first "repair?"
One possible clue (cause?). At the dealership, we exchanged the black plastic valve stem caps for some nicer silver metal ones. Does the TPMS system rely on some sensor embedded in the plastic ones (they looked like the regular cheap plastic ones to me)?
01-04-2008, 05:18 AM
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Was your car sitting on the lot for awhile? The sensors charge up from the
rotation of the wheel. I had the same experience when I just had them installed into new wheels. As I was driving, I would reset the TPMS but it would come back on. After a 3-5 miles, the setting took and all was good.
01-04-2008, 06:24 AM
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you probably need to drive after you reset since it use wheel rotation for TPMS
sound like u reset in the garage and just park there so i probably never really reset it. the reason that it didn't warn you when u turn the car on and off was because you didn't drive and hence the TPMS haven't have chance to read the rotation yet
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01-04-2008, 09:11 AM
#8
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I think you're right. I did reset it in the garage. Just reset it again on the road...
after driving around 5 miles, and so far so good. Will report back soon...
01-04-2008, 11:50 AM
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The car does NOT use wheel rotation to sense low pressure. The
pressure sensors are part of the valve stem assembly. See a photo of them on the Tire Rack website. They transmit to the car by radio frequency. I've found that using the reset instructions in the manual works most of the time. Occasionaly it make take 10 minutes of driving for the warning light to go out after a reset.
Cheers,
Cheers,
01-04-2008, 12:27 PM
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But he is correct in that they require the 'rotation' to charge the internal battery
required for it to function and transmit the RF signals.
--------------------------------------
More info:
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One tire pressure sensor is mounted to each wheel in place of the traditional tire valve stem. Each sensor has an internal battery that lasts up to 10 years. The battery is not serviceable. At the time of battery failure, the sensor must be replaced.
The TPM system operates on a 315 MHz radio frequency. The 315 MHz sensors can be easily identified by a white outline oval (black center) insignia on the sensor body (The Export TPM system operates on a 434 MHz radio frequency).
The valve stem caps and cores used are specifically designed for the tire pressure monitoring sensors. Although similar to standard valve stem caps and cores, they are different. The valve stem cap has a special seal inside to keep moisture and corrosion out. The valve stem core has a special nickel coating to protect from corrosion.
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.
Using an RF signal, each sensor transmits tire pressure data approximately once every minute. Each sensor's (transmitter) broadcast is uniquely coded so that the wireless control module (WCM) can monitor the state of each of the sensors on the four rotating road wheels. The WCM automatically learns and stores the sensor's ID while driving after a sensor has been replaced. There is no formal retraining procedure necessary.
--------------------------------------
More info:
--------------------------------------
One tire pressure sensor is mounted to each wheel in place of the traditional tire valve stem. Each sensor has an internal battery that lasts up to 10 years. The battery is not serviceable. At the time of battery failure, the sensor must be replaced.
The TPM system operates on a 315 MHz radio frequency. The 315 MHz sensors can be easily identified by a white outline oval (black center) insignia on the sensor body (The Export TPM system operates on a 434 MHz radio frequency).
The valve stem caps and cores used are specifically designed for the tire pressure monitoring sensors. Although similar to standard valve stem caps and cores, they are different. The valve stem cap has a special seal inside to keep moisture and corrosion out. The valve stem core has a special nickel coating to protect from corrosion.
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.
Using an RF signal, each sensor transmits tire pressure data approximately once every minute. Each sensor's (transmitter) broadcast is uniquely coded so that the wireless control module (WCM) can monitor the state of each of the sensors on the four rotating road wheels. The WCM automatically learns and stores the sensor's ID while driving after a sensor has been replaced. There is no formal retraining procedure necessary.
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