I raised my mini up on jackstands. Running the front wheels in gear does not produce a flat tire light. Is this valid test?
This did not cause the speedometer to indicate anything. Speedo gets info from rear wheels????
Have had two flat tires and the monitor never lit. Where is the unit located? Book says behind taillight housing (right side). Nothing there on my car, if they mean the passenger side (US version).

 

MC or MCS???

 

2003 MC 5spd

 

The flat tire monitoring is done by the ABS computer. It monitors all four wheel speeds and picks up discrepancies over time. It may take several miles of driving for it to pick up a fault. I've had the light flash when I had an actual flat (once) and when I had swapped from summer to winter wheels.

To test the system, make sure 3 of the tires have healthy inflation pressures and lower the fourth tire to half that pressure. Drive around for a bit.

 

>>The flat tire monitoring is done by the ABS computer. It monitors all four wheel speeds and picks up discrepancies over time. It may take several miles of driving for it to pick up a fault. I've had the light flash when I had an actual flat (once) and when I had swapped from summer to winter wheels.
>>
>>To test the system, make sure 3 of the tires have healthy inflation pressures and lower the fourth tire to half that pressure. Drive around for a bit.


In case andy's test isn't clear enough, You should set the tires to proper inflation, then reset the tire pressure monitor with the button under the handbrake. Drive around, mostly straight, so the system can learn the tires. This can take from 1 minute to 5 minutes depending on how consistent the wheels are rotating (no rough road, lots of turns, hard accels, abs stops). This is where the ABS system is learning your individual wheel tolerances with respect to each other.

After it is learned, deflate one tire (rear is better for safety) to much lower, 20 or 15 psi. Carefully drive around. The lamp should come on after you've driven a short while under similar conditions above.

I emphasize that the system is learning. Because of this, it tries no to learn if it can't be certain that wheels should be driving the same speed. The algorithm is based on calculated wheel speeds from each wheel. It determines that one wheel is 20.1 mph, another is 20.2, another is 19.8, etc. and determines that this difference is from tire wear and/or tire pressure. If the tires don't keep this proportion it determines that that tire is going flat.