How Toyota Highlander Tire Pressure Warning System Works

by Jody L. Campbell

The Warning

A strange warning light comes on the dash of your Toyota Highlander--a yellow exclamation point surrounded by parenthesis. If you look it up in the owner's manual, you'll discover it's the TPMS (tire pressure monitor system) warning light. Most all vehicles manufactured in the year 2007 and newer are now coming equipped with TPMS systems as standard equipment. This is a step to reduce fuel economy (because under-inflated tires actually reduce the gas mileage your vehicle gets) and to make it safer for the driver to prevent tire failure. Not all vehicles use the same TPMS system or sensors, however. The Toyota Highlander has a pre-programmed sensor as part of the valve stem of the wheel. This computerized valve stem monitors the air pressure in each tire and sends a radio signal to the computer of the Highlander. If the air pressure in one or more of the tires goes below 20 percent or 6 to 8 pounds of the other tires, this TPMS warning light will illuminate on the dash. The Highlander may even have a sensor incorporated with a full-sized spare tire, so be sure to have that checked, as well.

The TPMS Sensor

Each sensor is part of a valve stem, and special-care needs to be applied to these sensors when changing tires or repairing tires. The sensors are attached through the valve stem hole of the rim by hex head nuts. These sensors should be removed from the valve stem position by removing the hex head nut and dropping the sensor into the bladder of the tire before breaking the tire down to replace or repair. Otherwise, there is a risk of the bead of the tire coming off the rim that could incur damage to the sensor. And these TPMS sensors average around $100 or more per sensor from Toyota to replace. Not to mention they would have to be reprogrammed. The dealer isn't going to do that for free, either.

The Reset Button

You can reset the TPMS system on your Toyota Highlander. There are instructions in the owner's manual on how to do so. However, resetting the system without checking the cold-air inflation of the tires is not necessarily solving the problem. The recommended tire pressure inflation sticker is located on the driver-side door frame. On the Highlander, it calls for 30 pounds per square inch (psi) of tire pressure per tire, including the full-sized spare. If the Highlander had a donut spare tire, it will not have a TPMS sensor and subsequently will not effect the TPMS system one way or the other. To reset the TPMS system in the Highlander, there is a reset button under the driver-side dashboard that needs to be held for a period of time (a few seconds) while the ignition key is in the "key-on/engine-off" mode. The TPMS warning light will blink rapidly for a few more seconds, and the system will reset itself. Refer to the manual for the exact procedure. If the TPMS warning light reoccurs, have the system or tires checked by a professional.

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