: Need Help: Low Tire Pressure light keeps turning on

12-08-2005, 08:00 AM
My low pressure light keeps activating but all the tires are perfect. Is there some way to clear this problem?? Thanks for your help in advance.

12-08-2005, 11:21 AM
Did you reset the pressure and reinitialize the tire pressure monitor?

12-08-2005, 11:36 AM
MAy be a stupid question but how do you reset it and reinitialize the pressure monitor. thanks keith

12-08-2005, 04:03 PM
Under "settings" on Idrive, hit FTM, then set. Set the right tire pressure before hand.

12-08-2005, 07:33 PM
Thanks guys, I appreciate your help!!

01-09-2006, 02:25 PM
I have also discovered that the pressure in the spare tire is used as a reference. So, make sure its at the proper pressure before re-setting the TPM.

01-09-2006, 03:28 PM
After setting the pressure to your desired amounts, you need to re-initialize the FTM with the engine running, and in park.

Once you send the reinitialize command with your iDrive controller, you will see a message that says, "Reinitializing FTM, please wait." (you may move iDrive off the FTM screen during initializing, it will continue the process)

You then need to drive the car, somewhere between 10-30 minutes so the FTM system can re-learn the pressure relations between wheels.

To the best of my knowledge, the spare is not monitored. At least in my 04, it is definitely not.

01-09-2006, 08:14 PM
I had a devil of a time with the TPM. Finally figured out that the spare tire is used as a "reference pressure" in the system. Pump the spare up to range, then re-set (or "initialize") the TPM.

I found that my TPM only re-set when I would (in this order):

1. insert the key, turn on power (but not start the engine);
2. initialize the TPM via the i-Drive;
3. start the engine and go for a nice 25-minute drive.


01-09-2006, 08:44 PM
Finally figured out that the spare tire is used as a "reference pressure" in the system. Pump the spare up to range, then re-set (or "initialize") the TPM.
Interesting....last time I reinitialized it, the spare was at the tire shop being checked for a leak. After driving (re-learning) it initialized without the spare in the vehicle.
In my car (04 e66), the front and rear tires are different sizes. The spare is the size of the front tires. There is a 10psi differential between the front and rear (F-35/R-45).
I'm not certain exactly how the FTM system works, but I do know it recognizes a differential between 2 targeted tires, e.g. LF-RF; LR-RR; LF-LR; RF-RR, etc.

Perhaps someone here can explain how the FTM system actually works?