New X5 - Low Tire pressure warning - cold weather?? anyone??

[SANguru]

last time I checked, the TPMS just calculates rotational differences between tires and that's why there's no actual pressure in the reading. Just nitrogen fill it and be done with the psi fluctuation.

[KEF]

Originally Posted by SANguru

last time I checked, the TPMS just calculates rotational differences between tires and that's why there's no actual pressure in the reading. Just nitrogen fill it and be done with the psi fluctuation.

You are mistaken; in this vehicle there are actual pressure senders for each tire transmitting data.

The old E46 system is as you described using the ABS sensors.

KEF

[Fastbuck]

Originally Posted by KEF

You are mistaken; in this vehicle there are actual pressure senders for each tire transmitting data.

The old E46 system is as you described using the ABS sensors.

KEF

The systems are different depending which world market you're in. My UK version of the E70 detects a flat based on rolling circumferance.

[SANguru]

Originally Posted by KEF

You are mistaken; in this vehicle there are actual pressure senders for each tire transmitting data.

The old E46 system is as you described using the ABS sensors.

KEF

It's in the technical bulletins on DCS. Also, you wouldn't have to reset the TPMS after each tire pressure change if what you say is true. My 430 has a real TPMS and the sensor on the stem is very different from the one in both my 335i and the X5.

[KEF]

Originally Posted by Fastbuck

The systems are different depending which world market you're in. My UK version of the E70 detects a flat based on rolling circumferance.

I do not believe that is the case, but I could be mistaken. We have discussed this here countless times:

"BWM used two different types of tire pressure monitoring systems the Tire Pressure Control (RDC) system, and the Tire Defect Indicator (RPA) system (formerly know as the “DWS” system). The RDC system uses pressure and temperature sensors installed in each wheel as part of the valve stem. The sensors transmit their individual tire data to antennas mounted in each wheel well that feed to the RDC controller. This system is technologically superior, because it can alert you to absolute pressure changes (like when all four wheels decrease pressure over time), it is more sensitive to slight changes, and it can react faster. The disadvantage to the RDC system is that it puts a few ounces of extra weight in each wheel, and the system is more expensive and labor-intensive to retrofit. The RPA system uses the speed pulses from the ABS controller to calculate their relative rolling diameters. The advantage of this system is that it is passive (does not add “stuff” to your wheels and lots of extra wiring) and less expensive and easier to retrofit. It’s down side is that it is not as sensitive to pressure changes."

[KEF]

Originally Posted by SANguru

It's in the technical bulletins on DCS. Also, you wouldn't have to reset the TPMS after each tire pressure change if what you say is true. My 430 has a real TPMS and the sensor on the stem is very different from the one in both my 335i and the X5.

You are in the US: the TPMS system in the US has real pressure senders, here is the assembly:

[KEF]

Originally Posted by SANguru

It's in the technical bulletins on DCS. Also, you wouldn't have to reset the TPMS after each tire pressure change if what you say is true. My 430 has a real TPMS and the sensor on the stem is very different from the one in both my 335i and the X5.

Quote from page 94 of the '08 manual:

"Reset the system again after each correction of the tire inflation pressure and after every tire or wheel change"

Again, my X5 does use the RDC system for tire pressure monitoring.

Cheers,
KEF

[SANguru]

you completely missed the point of how the system works KEF. BMW uses the BERU TSS system. Only time it does an actual read of the tire pressure is when a user initializes a reset which then takes the pressure reading on each tire. From that point on, the system reads ONLY rotational difference between side to side, front and back etc. The system is not designed to read constant tire pressure which is what people are asking here. Here's the excerpt from the Technical bulletin. BTW, BMW uses RDE002 sensors which does not support constant read of tire pressure. It would be a nice hack if you can retrofit the RDE001 sensors used in the MB, Ferrari, and Porsche and then hack Idrive to show the tire pressure real time.

Nominal Pressure Input

The actual tire pressure after adjustment is
either initialised by the driver pressing a
button or the system adopts nominal pressures
memorised in it for the vehicle type to
which it is fitted. The system checks the
plausibility of pressure inputs, for example
the minimum pressure or differences between
the front and rear, left and right
tires. If the tire has been inflated correctly,
its pressure is then monitored; if not, the
driver is requested to correct the pressure.
Correct tire pressures are essential for optimum
ride comfort in the sense of low
rolling noise, freedom from sharp vertical
movements and sensitivity to transverse
road-surface joints. After the vehicleÕs
wheels have been changed (for example
winter tires fitted), the system is capable of
identifying the new wheels and their fitted
positions.

Originally Posted by KEF

Quote from page 94 of the '08 manual:

"Reset the system again after each correction of the tire inflation pressure and after every tire or wheel change"

Again, my X5 does use the RDC system for tire pressure monitoring.

Cheers,
KEF

[KEF]

Originally Posted by Fastbuck

The systems are different depending which world market you're in. My UK version of the E70 detects a flat based on rolling circumferance.

FB, I saw your RF post on the same subject as I am a member there as well; I am curious, what does your valve cap look like, here is what the US version is:




The reason I ask is because I do not have access to the wheel assembly on the non-US cars, so I am curious.

Thanks
KEF

[KEF]

Originally Posted by SANguru

you completely missed the point of how the system works KEF. BMW uses the BERU TSS system. Only time it does an actual read of the tire pressure is when a user initializes a reset which then takes the pressure reading on each tire. From that point on, the system reads ONLY rotational difference between side to side, front and back etc. The system is not designed to read constant tire pressure which is what people are asking here. Here's the excerpt from the Technical bulletin. BTW, BMW uses RDE002 sensors which does not support constant read of tire pressure. It would be a nice hack if you can retrofit the RDE001 sensors used in the MB, Ferrari, and Porsche and then hack Idrive to show the tire pressure real time.

Post a link to the technical bulletin if you don't mind.

Aside from this, the vehicle is operating with the RDC system that does that the Bero transmitters and is not functionally equivalent to the RPA (ABS E46 style system) that only measures wheel spin off the ABS system.

You are supposed to reset the system after any tire pressure adjustment, and it calls it out as such on the valve stem cap!

Cheers,
KEF