Toyota Repair: solara 04, rubber valve, tpws

Question
I have recently turned 81,000 on my 4 cylinder Solara and the maintenance light has come on - what should I be checking?  Also, my tire light comes on way to frequently even right after I have had it checked and serviced - what's the deal with that?
Thanks!

Answer
I don't know the maintenance history of the car but it's due for a major maintenance service at 90,000 miles. There are two types of tire pressure warning systems,the direct and the indirect system, to find out which you have look at the valve stems, the direct TPWS system has metal valve stems the other one has rubber valve stems, the direct system has sensors in the tires that send a signal to the TPWS system computer which monitors the pressures, one of the sensors may be malfunctioning or there is a leak in one of the tires, if it uses this system then the car  should be connected to the diagnostic scantool to see which one of the tires has the problem, if it has rubber valve stems then there could also be a problem with a leaking tire, this system has a reset button on the lower part of the dash, it's reset by turning the key off, then back on while holding the reset button until the warning light blinks three times.