My tire pressure sensors are confused

Recently my tire was low. Filled it up and a day later it was lower. Uh, oh got a bad leak. Fill it up and take it to a shop. Shop said tire has a small slice and can't be patched.

They put on my spare and sent me on my way. Life did not allow me the time to stick around and wait for a tire. Again, life has kept me from getting a new tire. Monday. I've lined one up for Monday.

Ok so here's the scenario: start truck and low air thingy rings and says I have a low tire in the location of the fully inflated spare. Tire 4. Check old tire hanging under the truck (tire 5) and it reads the same number on my guage as the dashboard says the one on the truck is.

Drive to work and alarm rings and says pressure sensor failed. Get to work, turn off truck. Turn it back on and the dash thinks all four are full now. It's reading the sensor on the spare now but…… 5 miles down the road and the pressure sensor fail alarm rings again.

It's as if the vehicle thinks tire 5 is located on the hub at times and other times it thinks tire 4 is located on the hub. Then at times it thinks there aint a tire with a sensor at all on the hub. It's a Ford. Guy at the Ford dealer said the spare does not have a sensor.

My boss told me his wife's Honda does the same thing.

Anybody else ever have this issue?

I can't explain all of whats going on, but, tire sensors go to sleep if the wheel is not spinning. It has to do this to prolong the sensor battery life. So when the truck is moving, the truck wants to see 4 sensor readings, but since 1 is asleep, the truck is only seeing 3 sensor readings and concludes that 1 has failed, but its really just sleeping.

I have an F150 and I don't think the spare has a sensor. If syga is correct, then maybe what's happening is the battery in the sensor is getting low. When the truck stops, sensor goes to sleep, battery has a chance to rest. Truck starts moving again and the sensor comes on. Battery has enough juice to power the sensor normally but after a short period battery starts to die and you get the sensor failure. Everytime i go to a tire shop, they always ask me if I want to "rebuild" the tire sensors. Which is just basically a battery change and valve stem recondition.

Interesting Thread here !


I have a 2018 Ford Escape,
and (unless I'm missing something),
does NOT tell me *WHICH* tire is Low !

Simply says: "Tire Pressure LOW"
(or something similar)

It's MY problem to determine
WHICH of my tires is the Low one !
< groan >


Guess things are different on the F-150 ? ? ?


_

My wife's escape only has the yellow warning light too.

Now the sleep thing I kinda get, so maybe the spare one that currently is mounted on the hub falls asleep then a signal from the leaking tire is read? Then it too falls asleep? There are times the dash board shows the tire is low and other times it shows it is normal. Same tire location.

I'm glad for the sensors (when they work proper). The day it began to show up a cursory glance around the truck passed muster as the tire did not sag all that much at the time. Add air and it lost about a pound a day for a few days. Then one morning it was flat. Like 6 pounds according to the dashboard. It had been 32 the night before when I parked it so I figured I'd plug it myself that Saturday. But next day when it was flat I figured it shouldn't wait until Saturday and took it to a shop near my project. They said it would be a few hours until they could get a tire to replace my non patchable one. So they put the spare on for me and thus the story began.

One thing I've learned is when the dashboard shows the status of the spare is it still only leaks about a pound a day. The thing I don't get is if the spare does not have a sensor (which makes perfect sense so you won't keep driving on the spare or else the yellow warning keeps bugging you)……if the spare has no sensor why would the dashboard show the tire in the location of the spare has the same pressure as my tire guage reads (32)?

It came with Goodyear tires so I'm taking it to a Goodyear store on Monday and having them replace the leaking tire.

I don't think the sensors are able to tell what position the tire is actually in. My f150 is a 2013 and doesn't show tire position, so I don't have first hand experience, but from what I read, when you change the position of the tires on the vehicle (as in tire rotation) yiu have to go through a procedure to tell the vehicle's ecu which tire is where. The procedure requires you to get it into programming mode, then in a specific order, deflate the tire. When the ecu has determined which tire is being deflated, it will register that tire for that position. Then you go on to the next tire until all four are registered. So that would mean even if you take a tire and swap it to the spare location, or bed of truck, trunk, or next to it, it will still think the tire is still in its original position.

Almost every vehicle that tells you which tire is low needs to be reprogrammed any time you rotate your tires otherwise it will tell you the wrong tire is low. That is why many newer vehicles just have a yellow warning light as there is no programing needed when you rotate your tires. I think too many people were inflating the wrong tire instead of the low one. Many GM vehicles can be reprogrammed without special tools while most others can't. A good tire shop should be able to tell you what is happening on your vehicle for little or no cost. A good question to ask them before allowing them to look at your vehicle is what TPMS tool do they use. If it's a Bartec, Snapon or similar your in the right place. If you get a blank stair go elsewhere.

If you got a full size spare, it has a sensor.

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Not true on all vehicles. My F150 for sure does not have a sensor in the spare. And it is full size.

mcm308 said:

If you got a full size spare, it has a sensor.

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Click to expand...

Sensor? No sensor in the spare?
Got me. All I know is at times my dash says the passenger rear is low. Other times it says it's fine and still other times it says there is no sensor signal to that position.

All kinds of good info here folks. Thanks.

The shop I'm dropping it off at has 3 mechanics. One has a 6 foot tall bright green Snap On tool box. Another has a Dale Earnhardt edition and the 3rd a Harley Davidson edition so I'm supposing they have a Snap On reader. And they have a real pissed off German Sheppard guarding the place at night.

There is no sensor in ford spare tires that I am aware of. I have trained (activated) sensors before on fords and have never trained a spare tire. And when you go into programming mode, it never tells you to train the spare tire.

On later fords, you can see the actual position of the tires and you know exactly which one is low.

Well, my Ford Escape is 2018,
and (unless I'm missing something),
does NOT indicate WHICH tire is the LOW one !

:thinking:
_

Our ten-year-old STS has the ability to show how much pressure is in each tire except the spare. When the warning light activates it doesn't show which tire is low. You have to go to the information switch on the dashboard to glean that information.

Burgess said:

Well, my Ford Escape is 2018,
and (unless I'm missing something),
does NOT indicate WHICH tire is the LOW one !

:thinking:
_

Click to expand...

I guess only just some. I was checking a dual rear wheel pickup and all 6 tires positions were showing.

+

The fact you can't replace the battery in your TPS' is nothing short of good lobbying.:thumbsup::thumbsup:



thick sarcasm here

I drove the truck to my dads on four fully inflated tires. Dash said passenger side rear was low. (16 pounds)

Drove home from my dads and the dash said the passenger side rear was fine. (32 pounds)

Original wheel back in place with original sensor and all returned to normal.

I got the impression somebody in the shop unplugged my battery or somehow reset the ECM because all settings were back to default.

...............

bykfixer said:

Original wheel back in place with original sensor and all returned to normal.

I got the impression somebody in the shop unplugged my battery or somehow reset the ECM because all settings were back to default.

Click to expand...

+

Good to know it was the other sensor.
On my post #15,, when I said 'you' I was referring to everyone/people in general

I'd rather replace a small Li-ion, than a $75 set.

has anyone replaced a cell in their tpms sensors? do they just come on normally, or do they have to be calibrated after? i never had to change batteries in them, but i do not keep cars longer than 3 years