2003 500 SL (4900 miles)
I am a careataker for this guys car collection. A daily driver is this 500 SL, I got in the car and turned on the ignition and a warning for the tire pressure monitoring system was displayed. I cycled through the menus to the to see what the current cold pressures were. To my chagrin, I found the tire pressures for the FR, FL, RL all to be 50 psi! and the RR to be 26 psi. He said he couldn't find what the pressures were suppposed to be in the owner's manual, so he read the pressure on the actual tire. I think he didn't notice the max. pressure just before the 50. Anyway, I fixed the problem, setting the fronts to 26 and the rears to 29. I told him where to find the information on the vehicle so he wouldn't make the same mistake.

Problem - The warning light still displays when the ignition is turned to the on position. Secondary display informs to toggle the monitoring system. How do I toggle the monitoring system on or off?

Thanks in advance.

__________________
Caretaker for...
2003 500 SL
1992 500 E
1986 500 SL Conv.
1967 250 SE Cab
1964 600 Limousine
1953 220 A Cab

I don't have the answer, but can anyone tell me how that system works? I assume that there is a transmitter mounted to each wheel. How long to the batteries last?

-Tad (Still catching up)

To reset, make sure you are on the screen with the tire pressures
displayed and the key is in position 2. press the reset button on the cluster shell (that also resets the trip odo) and hold. Display
will read "monitor current pressures? or reactivate system?"
and then will instruct you to use the + button on the wheel or
press the reset button and hold. This info can also be found in that massive owners manual under TPC for tire pressure monitor.
I would also recommend upping the pressures to 32psi front and rear which will keep the SL from munching on it's tires too fast.
Have fun.
DR.D

FYI When adjusting tire pressure don't use the tire pressure display instead of a pressure guage. Under normal conditions, the tire pressure info is only sent approx. once per minute. If the system detects a leak, the info transmission rate is approx. once per second. For cars that sit for long periods, frequent TPC re-activation is a way of life.

I'd love to know how this system works, can anyone give any details?

__________________
1985 190E 2.3L - a constant project.

Thanks for the input Dr. D. I got the problem fixed and running at 32 psi.

I researched this technology when it first came to market. There is a sensor that is banded around the inside of the wheel when the tires are mounted. This sensor then transmits a radio signal to a receiver in the car which sends the information to a display in the car. As far as the technology goes for the sensor to detect the pressure under a centrifical load when the wheel is spinning is beyond me.

__________________
Caretaker for...
2003 500 SL
1992 500 E
1986 500 SL Conv.
1967 250 SE Cab
1964 600 Limousine
1953 220 A Cab