Tire Pressure Reading

I “believe” Carista tells you four pressures but not how each temp maps to location of vehicle.

 

If it assigns an ID to each temp reading, you could drop the pressure in one tire, see which ID drops, then repeat 2 more times with other tires to sort out who's who.

Lot of work though, and you need to keep track of tire rotations. Yeah I know a family member's Pilot had a pictorial showing the car and tires, indicated which corner was low, with the tpms sensors.

 

My son's 2008 Highlander hybrid has a graphic showing the pressure in each tire. But for some reason that noone has been able to fathom, this information is not displayed on any Prius. The information is available (as with the Carista app), but just not externalized on any display.

 

Unfortunately no TPMS data display is available on the PRIME, by itself that is. If you want, you can use various tools that connects to ECU via OBDII to read out the TPMS sensor data. Techstream, Scan Gauge II, various OBDII apps like Carista, Tire Assistant or alike with compatible dongle will do the job. Also most of handheld TPMS scan tools like Autel will also work. But the cheapest would be just to use a manual tire pressure gauge.

 

As mentioned, Toyota for some unknown reason doesn't support that feature.

You can buy something like this dash mounted TPMS from Amazon for about ~$30 dollars, they work quite well.


Rob43

 

I just got one of these three weeks ago. So far so good.

Posted via the PriusChat mobile app.

 

I'm idly curious, with systems that do show tire pressure, or just warn that one is flat, AND indicate location, how does it figure out the location.

 

Are you asking about external TPMS like Rob is showing? If so, the sensor is labeled with the location of the tire. The radio signal from each sensor is fixed on the display unit.

And if you are asking about OEM TPMS with display on dash. At least for those Japanese cars that requires ECU programing, you do the programing in the order of ID that corresponds to the location of the display. This ensures the sensor data match the displayed location. I assume, for those cars with automatic detection feature, the location of radio signal must be distinguishable maybe with a directional receiver?

 

Yeah I'm thinking something like that last sentence. I mean wheels get rotated, the individual sensors could be at any corner of the car.

I have the shop manual for 2010 Pilot, which I noticed has that feature. I'll maybe take a look.

 

It's funny... several years ago, I owned a 2006 Mazda Speed 6. It was AWD, turbocharged, handled great! It had a derived TPMS system. It used the wheel speed sensors and angle sensor on the steering that calculated what each wheel should be rotating at. If the measured and calculated values didn't match, it would indicate a tire pressure problem. I never had problems with it, no TPMS sensors to go bad, for some reason, manufacturers didn't stay with the system. I have often wondered how the system keeps track of where each wheel is, especially when you rotate wheels and tires from front to back. I know there is a button that tells the car the tires have been rotated down under the dash, and I wondered if pressing this just moves the wheel positions in the ECU according to the recommended maintenance rotation scheme to keep track of where wheels are virtually (in the ECU) and match them with actual position. It would seem that pinging each sensor and somehow knowing (maybe signal strength or time to send receive) where each sensor is physically would be best, but I don't know.

 

At least for our Nissan with TPMS display, there is no mentioning of TPMS reprograming procedure after tire rotation. In my case, I do tire rotation at the time of winter tire change, so TPMS reprogramming is necessary. I don't know what happens if I rotate tires without TPMS re-programing on our Nissan. Humm, that's something I can experiment.

Indirect TPMS systems are back in some Honda models. All Civic, Accord, Clarity are with indirect TPMS. It works fine as a substitute for the dumb direct TPMS system without data display. The problem with indirect TPMS is that car has to be in motion to detect the lower pressure tire, and also in a very rare instance when two tires on the same axle lose the same amount of air, the indirect TPMS can not detect the lower pressure.

 

The new one I have (shown in picture) also allows me to digitally relabel the location of each of the four sensors. FWIW: Probably just gonna screw the cap-sensors off and move them at each rotation.

Posted via the PriusChat mobile app.

 

Ah: if the valve cap is the sensor, very easy to get the locations established on the display.

 

How much do those external sensors and batteries weigh? What do they do to tire balancing? Significant? Negligible?

 

Less than 10g each. Yeah, it would be off balance, but I have no idea how and what it affects. For one thing, when I was having winter and summer tires on the same rims, tire shop did the swap for free, but no re-balancing. I never had problem I was aware.

 

10 grams is about a third of an ounce.

 

Just trying to get an idea how much wheel weight is used, typically. Could be somewhere between one and four ounces.

https://blog.tirerack.com/blog/make-driving-fun-2/how-many-wheel-weights-are-too-many-

 

Each stick-on weight is a quarter of an ounce, the TireRack site says. So, if you worry about unbalanced wheel and tire by putting on the external TPMS sensor on the valve stem, just stick 1 or 2 stick-on weights on the direct opposite side of the valve stem.