eng208

How does the tire sensor work on an 07 4Runner? Ours will show a low tire pressure every month or so and we have to add air. I cannot find a leak in the tire and was wondering if it is a speed sensor type monitor system or actual air pressure monitor and could have a leak in the sensor.
Any help?
Thanks
Eng208

bwhyit

It's a direct (sensor) type system. If you have to add air then I'd say your tire has a leak somewhere. When the light is on does it actually have a low tire (including the spare tire)? If so then you'll need to look harder and find your leak. If not then set all your tires to factory spec. Make sure you set then when the tires are cold (not setting in the sun) and then re-intialize the system. You should have a button under the drivers side dash that says TPWS (check owners manual if you can't find it). Hold it until the TPWS light on the dash flashes 3 times and your done.

eng208

Is it possible for the sensor to have a connection that could leak? Thanks for the description. How does it make the physical air pressure monitoring connection from the tire to the vehicle? We just got this vehicle recently and have not crawled under it with a creeper to look at the design. I am totally familiar with the 95-03 Tacoma and 96-02 4 Runners.
And yes, do have to add air when the sensor comes on, it reads low with just as little as 4 psi change. I was impressed and like the feature since this is my wifes vehicle. BTW, I inherited the 99 4 runner and just did a TB and WP change.

bwhyit

The TPWS sensors are actually integrated into the valve stem. If you dismounted the tire you'd see that the inner portion of the valve stem contains the electronics that measures your tire pressure and temperature. It's a black rectangle shape. The only leak you could have sensor related would be around the valve stem portion. The sensors communicate with your vehicle wirelessly. The light should turn on when your tire is roughly 20% low on pressure.

This web site has come pretty good info: http://www.toyotatpms.com/

eng208

Thanks. So it must use a hall effect sensor.