Tire Pressure Sensor Sys.

[enjr44]

Ok, how does this system work? The 08 has the band type sensors. Turn key to run TSP light on, start it and light goes out. Since it is an FX4 with Level II options it rides, well, like a truck. You feel every pebble and seam in the road until you get above say 40 MPH. So I have the tire pressure at 27.5 psi to improve the in town ride.

Yesterday I found a screw in the tire tread. It wasn't leaking so I waited until this morning to get it fixed. When they pulled the screw it started leaking, they fixed it and set the pressure at 33 psi.

I expected the TPS light to come on on the drive home. It did not, why not??

 

[RonD]

TPS is for "flat tire" warning so will only respond to low tire pressure, not over inflation.
The assumption is that tires can only be over inflated by the owner(a person), so hopefully someone smarter that the TPS computer, lol.

But tires can lose pressure without the aid of a person, a leak, so that's when the warning will occur.

Cold and warm weather do change the internal pressure but it would be an equal rise and fall at all sensors so shouldn't trigger the TPS.

 

[enjr44]

Thanks, Ron

The Ford system must be different than Honda's. On the Wife's Pilot it compares the tire pressures and responds when one is 3 or 4 pounds different from the others. But, again, the Honda tells you which tire is different.

 

[adsm08]

Also, I'm a bit surprised the light isn't coming on at 27 PSI.

 

[enjr44]

Also, I'm a bit surprised the light isn't coming on at 27 PSI.

Well, I have no clue. I thought you once said that you had about 4 to 5 pounds to play with and the door sticker says 30 psi. Once the weather gets warm, I'm going to have to go play with it.

 

[naford]

On my Venza it comes on when one tire is roughly 10 PSI below the other tires. But I thought they didn't use the system on off road type trucks.

 

[JohnnyO]

Different systems work differently. On a Cadillac my dad used to have the dash display would give you the exact PSI in each tire. Other systems tap into the ABS or stability control and look for differences in tire RPM and if one is spinning faster (an under inflated tire will be smaller and spin faster) past a certain percentage it will trip the light. Late model Fords have wheel sensors, I don't know if they look for speed or PSI, but the main problem is that the batteries go dead after a few years. The light on my Sport Trac was on most of the time so I dropped $200 for new sensors last year when I got new tires, had the dealer reset them which they did for free but the light is still on at least half the time so I fixed it with a piece of black electrical tape over the warning light.