Eddie Knopp

Something weird is happening - wonder if anyone has any advice - needed to have a front wheel changed (accident - don't ask) and when I got the car back the TPMS no longer indicated individual pressures - I figured the dealer had reflashed some software. I mentioned it to them when they put on my snows - and they "fixed it". That evening when I picked up the car it was back to normal. The next morning however, it's back to the same monitoring system active. Anyone have any thoughts ? As you might imagine - here in the NE I use the numbers quite frequently this time of the year with all the potholes.

Thanks

Diesel Benz

Can you tell a bit of more background. When the wheel was first changed, did it also get a new TPMS sensor or was the old sensor from the failed wheel put back?

What about the winter tyres, was it first time for those wheels or were the wheels (specifically sensors) used before?

I recently learned that the Siemens sensors come from the factory (spare parts) in test mode (this might not be for all sensors but I understood this being typical). The sensors would have be ordered to normal operation mode. This can be done with a specific tester or by driving the car for minimum 5 minutes at a minimum speed of 25 km/h. If the speed drops momentarily below 25 km/h, the 5 minute timer restarts!

If this learning phase has been conducted, then it should be sufficient to check that all tyres are properly inflated and the system restarted from the instrument cluster and the car is driven until the readings appear. "A few minutes" of driving should be sufficient.

Eddie Knopp

Thanks for your input - to answer your questions - I do not know (but can find out) if the orig sensor was used. If they are easy to swap out I would guess it was. In terms of the winter wheels they are new - direct from Tirerack with sensors installed. I will test your hypothesis and go out for a drive and restart and see.

I'll let you know.

Thanks

Eddie

czwbkx

Tire Rack sells Beru sensors rather than Siemens so that's likely what is in your winter set. I don't know if there are any issues with mixed brands or if there is any initial setting on the Beru - may be worth a call to your Tire Rack sales person.

Eddie Knopp

Could be - I'll check with Luke. I tried what Deisel Benz had suggested but still no #'s. The actual pressures were there when I picked it up after the winter tires were installed.

hubitubi

when the tpms is not detected by the car (when u remove a rim)....
and after the tpms is detected again (by putting tire back on car), you have to have the car turned OFF for at least 20 minutes before the tpms works properly

i found out after swapping my amg rims for modsports

Diesel Benz

Off topic but the W221 TPMS system is from Siemens, as on all current MBs. I am not aware of any Beru sensor that would work in the Siemens setup. Would you have some pointers?

Diesel Benz

I didn't read the case properly, I did not understand that you have no readings. I have not tried a car with Siemens sensors but from a previous discussion I remember those being "slow", would not give a reading immediately and the one you saw must have been a "previous reading".

Could it be that the car was installed with Beru sensors that do not work in this car?

Diesel Benz

This is a good point too, I've seen it in the car manual but had forgotten as the Siemens sensors work differently from the Beru sensors that I'm used to.

I assume the car has now done everything necessary (as if sensors were changed or if any sensor was in test mode initially) and it should start operating after TPMS initialisation from the IC. Since it does not, it really feels like the sensors aren't good.

Eddie Knopp

Guys -

When I got the car back after the snow tires/wheels were installed the system did indicate individual tire pressures - I was told they "reset" something - the next day the system reverted back to not indicating pressures. I'll see if I can get more info from the dealer today.


Thanks

Eddie