lynn mcguire

Driving home from Abilene, Texas to Sugar Land, Texas
(about 350 miles) yesterday, my tire pressure monitoring
system came on twice for a couple of miles with a system
failure message in my 2005 EB Expedition. I stopped the
first time and visually inspected the tires. Hitting the reset
button cleared the message each time.

I have about 26K on this truck with no problems whatsover.
I have a semi new set of Michelins on it with about 8K miles
(the orginal Continentals were crap).

Could it be something on highway 36 was messing with the
RFID system this uses (I think) ? Or, is my tire pressure
monitoring system getting ready to fail ?

Thanks,
Lynn

c. e. white

I assume you verified that the tires were properly inflated? You need to
check the prssure when the tires are cold at outside ambient temperatures.
They need to be properly inflated within 3 psi.

Ford cautions that the valve stems can be damaged by improper treatment.
There is also a procedure for re-training the tire sensors, but it requires
a special tool (really just a big donut magnet).

What was the exact message? I believe the possible message are:

"TIRE PRESSURE MONITOR FAULT".
"TIRE PRESSURE SENSOR FAULT"
"LOW TIRE PRESSURE"

Ford provides the following warning:

"Ambient Temperature Change and Tire Pressure

"If tire pressure is adjusted/set indoors, additional care is needed in the
winter months to achieve the correct inflation pressure. Since the tire
pressure will drop with temperature, the tires need to be inflated above the
specifications given on the vehicle certification (VC) label while indoors
during winter months, so the tire pressure is at the pressure listed on the
VC label when parked outdoors.

"As the ambient temperature decreases by 12°C (10°F), tire pressure
decreases 7 kPa (1 psi). Adjust the tire pressure by 7 kPa (1 psi) for each
12°C (10°F) ambient temperature drop as necessary to keep the tire at the
specified vehicle placard pressure. For additional information on tire
pressure adjustment, refer to the following table."

I would wonder if the sensors might have been damaged when the tires were
changed. Here is a little information on the sensors:

"Each tire pressure sensor transmits a specific radio frequency to the TPMS
module once every minute when the vehicle ignition is on. The tire pressure
sensor valve stem serves as an antenna which sends the radio signal to the
TPMS module. The tire pressure sensor is battery powered. "

Do all your valve stems look OK?

Which Michelin Tires did you purchase?

Did the tire dealer understand the tire pressure monitoring system
requirements? Mounting new tires might require the sensors to be reset. Did
they do that?

Before you purchased your repalcemet tires did you read the following
information in your owner's guide?

"The installation of replacement tires with steel cord body plies in the
tire sidewall may cause malfunction of the Tire Pressure Monitoring System
(TPMS), and is not recommended (cord material information is molded on the
tire sidewall). Additionally, if your vehicle was originally equipped with
run-flat tires, replacing them with tires that are not identical to those
originally fitted may cause malfunction of the TPMS, and is not recommended.
Run-flat tires should not be used to replace regular tires. Always check
your TPMS indicator immediately after replacing one or more tires on your
vehicle. If the TPMS indicator is on, your TPMS is malfunctioning. Your
replacement tire might be incompatible with your TPMS system, or some
component of the TPMS system may be damaged."

.....

"Important: Remember to replace the wheel air valves when the road tires are
replaced on your vehicle."

If your vehicle is still under warranty, I suggest you take it to the
dealer.

I recommend you join the Expedition Owners Mailing List See:
http://mail.xpog.com/mailman/listinfo/expedition

Ed

TPMS operates on different frequencies according to the vendor; some
are 2.4GHz ISM, some are 315 or 433MHz. All of these frequencies are
unlicensed(*) and subject to interference. It is possible - but not
real likely - that you were experiencing interference from a 2.4GHz
RFID system - these are sometimes used for tracking trucks and
shipping containers.


(*) in the technical sense of the term.

lynn mcguire

They looked OK. Sidewalls were stiff and not buldging.


TIME PRESSURE MONITOR FAULT, I believe. The word FAULT
was definitely in there.


It has been 8,000 miles since I replaced the tires. I have been to
California and back (3500 miles) and this is my 2nd trip to
Abilene (750 mile round trip).


I am surprised it is not 60 times per minute. Hmmm, battery
powered sounds fraught with failure since that pressure
sensor is in a very harsh environment.

yes.

Michelin X tires from Sams Club.

Nope and nope.


Nope.

Dont know.

Thanks,
Lynn

c. e. white

You need to actually check the pressure with a gauge. Looks can be
deceiving, especially with radial tires. Be sure to inflate them to
the correct pressure listed on the vehicles information placard.


Sound like you should take it to the dealer. The monitor system stores
fault codes that the dealer can retrieve.

The monitor is safe inside a closed environement. It probably gets a
lot of shock, but that won't hurt a battery. If you want to directly
monitor tire pressure this is about the only way to do it. There are
other systems that determine that a tire is loosing pressure by using
the ABS wheel speed sensors, but they are less accurate and less
responsive and are upset it the tires aren't matched or when you rotate the tires.


I don't think these shoul dbe a problem ( are they P series tires?).

lynn mcguire

I know but I could reset the system OK. Even restarted the engine
and did not get the message again.

I will if it hits again.

Yes, sounds like a good system.

P265R75-17, I believe.

Thanks,
Lynn

Maybe just pull the fuse and be done with the ridicuous monitoring
system. You can check manually with no stupid codes