TPMS Messing Up?

It's getting closer to Fall, which means a some cooler temperatures in the mornings where I'm at, and with that, of course, comes some low tire pressures. With that being said, every morning for the past week my Tacoma has shown that my back right tire is low. I don't suspect a slow leak, because by the evening when the temps are back in the 80s/90s the pressure goes back up and the low tire alert goes away. Well, I've noticed on several occasions both rear tires will show the same PSI, but only the right tire will be flagged as being low, as shown in the picture below. So basically, does anybody know why this would be happening, or is it a sign that the TPMS in one of the rear wheels is malfunctioning? I know that the light is supposed to blink if one is malfunctioning, and that has not occurred as of this time.

 

I had that a couple weeks ago. Hard weather came through and our average temps plummeted from 102 to 79 overnight. Tires lost 8 pounds. Swung through dealership, they took me back up to 36, and I've been fine since.

Must be a new computer feature to automatically rotate summer and winter air. I sure hope it has an auto blinker fluid refill too.

 

Thanks for reminding me, I forgot to do mine last year!

 

I'm 4-6 PSI lower on all 4 tires in the morning than I am in the evening. I will eventually put more air in the tires to compensate for the pressure changes, but it was just strange that one TPMS flagged 27 PSI as low and the other TPMS didn't.

 

Depending on the kind of weather you get where you're at, nitrogen is an option. More stable across a larger temperature range and less temperature compression/expansion. My dealership will always fill me up for free (wifey's car).

 

Where I am I can see a swing of 4-5 psi over the day. Totally regular, though I do try to make sure that my tires are close to even. I got by using a manual psi gauge just fine before getting a car with a version of TPMS.

I have no idea what triggers the orange highlight. I used to think that it would highlight a tire if it was lower than a certain threshold, but that's not true. I was able to grab this pic this morning:


The manual (pg 527) says the warning "Indicates that the tire inflation pressure is low." Thanks for the help Toyota...

Sub'd for any more info.

 

Refill air to proper winter temps accounting for less internal pressure changes for winter time and reset the TPMS system. Button is on lower IP panel near the knee. I forgot what the threshold range was for +/- range on PSI once you set it, but resetting the system (once set and you drive for a few miles) should resolve that since your TPMS system was likely set during warmer seasons. Just make sure to pair up axle PSI numbers if you stagger the pressures. I did so on mine. Only time my monitor light comes on is when I air-down to 20 PSI when in the dirt, but once pressure is back up, it's all good and no need to mess with resetting again.

 

Worth a read: https://www.edmunds.com/car-care/should-you-fill-your-cars-tires-with-nitrogen.html

I stick to a 78% Nitrogen / 21% Oxygen mix for my tires and can adjust/top-up pressure at home on three vehicles in less time than a trip to any dealer.

 

This makes sense. I did reset the TPMS without "leveling" the four tires, so let's say front left was at 32 and back left was at 30. Then it gets cold and both tires drop to 29 (let's just assume here). The front tire sees a drop of 3 and the back tire sees a drop of 1. If the threshold +/- value happened to be 2, the front tire will get the flag and not the back tire.

Thanks for the response.

 

It highlights when the tire's deviated a certain amount from where it was when you last did a TPMS reset. That can be different for different tires if you didn't have them all set the same when you last set the TPMS.

Edit: whoops, you replied as I was typing. Glad ya got it now.

 

Well then screw the dealership. Good article.