Reggie1

My low tire pressure warning light came on this morning, coinciding with the morning temperature here being about thirty degrees lower today than yesterday. So, I looked at all the tire pressures on the dashboard display, and all 5 tires displayed were 29-29-30-31-30 psi. I got out my compressed air tank inflated the rolling 4 tires tires to 32 psi. When I started the engine, the tire pressure warning light went out, and when I checked the dash display, the numbers were 34-34-35-35 psi for the 4 tires I'd added air to.

I used second and third tire gauges to re-check the tires, and all 3 gauges (2 digital and 1 analog dial-type) showed that all 4 tires were at 32.psi. So assuming that all 3 of my tire gauges are accurate, my dash display reads and displays higher than actual tire pressure. Has anyone else compared the dash readings to actual?

And, is the TPMS warning light illuminated based on an actual drop in pressure of a certain number of pounds per square inch, or on a percentage decrease?















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hankinid

Toyota's TPMS looks not only for psi set pressure but also for variation either up or down. TIS aka Techstream can do it, but only if the senders are recognized as belonging to the vehicle...i.e., the Tundra senders in my tundra wheels with Blizzaks mounted for winter won't link to my Land Cruiser's TPMS ecu. It also can only store 5 sensors at a time. As TPMS systems go, imo Toyota's suffers from major suck-age. There's a bunch of recent discussion on the 200 series forum on mud discussing TPMS, you might want to check it out.

When mine gets its sunny weather AT II's back on, pressure is usually around 80 to 90% accurate to my calibrated digital and dial gauges. That said, I see it similarly to the Low Fuel light. If that's all you think you need fine, but you've got no plan B. I fill the tank before LF illuminates, and I check tire pressure at least twice a month if I'm home, and every day on a road trip or a trip with no roads.

mikeivan

My dashboard tire pressure numbers are pretty close to my gauge numbers (+/- 1 lb) . My low pressure warning light, not so much. YMMV.

ggebhardt

Mine are never more than one pound off. Most the time, right on the money.,

Reggie1

The answers indicate that the displayed pressures should be more accurate than mine are. Could this mean that the sensor batteries in my wheels have reached the end of their lives? Google says these batteries last between 2 and 5 years, and my LX is 4 years old. The dealer replaced my tires within the past year, but I am assuming that the pressure sensors are not routinely replaced nor are their batteries, if these batteries are even replaceable.

I also read that Toyota vehicles have a problem with corrosion inside wheels, leading to premature TPMS sensor battery failure. The problem reported is mainly in Toyota wheels with aluminum valve stems rather than the rubber ones, and mine are metal. Could this be related to my erroneous readings?
And, ;last question. Would re-setting my TPMS recalibrate the sent pressures with the dash display.