Well I changed to the summer tire and rims on our minivan (a nice Sunday DIY job). While I had the compressor and tire pressure guage out I decided to check the trucks tires. I wasn't too concerned as the TPMS had not gone off so it shouldn't be off the door stamped 35psi. Yeah I know it isn't a substitute for checking the pressures but I had it through a shop a month or two ago for the first oil change and tire rotation etcand I ASSumed it was checked then.

Well the highest pressure was 26psi and the lowest was 22psi....

Grabbed the owner's manual to see if I could find out what pressure would have triggered the TPMS and this is what I readUmmm isn't 2/3 of the recommended 35psi a significantly underinflated?

And then on top of it while filling the tires, I notice that these Michelins have a max pressure of 35psi same as the door stamp recommendations. THis is the first time I have seen tires rated to such a low max pressure.

 

i may be wrong but i think they way the tpms sensor light on the dash is programmed, it will only go off if one tire is significantly different from the others as far as pressure. So if they all lose air at the same rate over time the light will not go on even though they could all conceivably be flat.

 

Heres what I can find in the service manual dont know what the tool is they refer to

The Tire Pressure Monitoring System (TPMS) monitors the air pressure of all 4 road tires. The wheel-mounted
tire pressure sensors transmit via radio frequency signals, to the Smart Junction Box (SJB). TPMS functionality
is integral to the SJB . These transmissions are sent approximately every 60 seconds when the vehicle speed
exceeds 32 km/h (20 mph). The TPMS function (integral to the SJB ) compares each tire pressure sensor
transmission against a low-pressure limit. If it has been determined that the tire pressure has fallen below this
limit, the SJB communicates this on the vehicle communication bus to the Instrument Cluster (IC). The IC then
illuminates the TPMS indicator and displays the appropriate message(s) in the message center (if equipped).
This symptom can also be caused by a spare tire currently being used in place of a road tire. Make sure that the
spare tire is not currently in use. On vehicles with different front and rear tire pressures, if the sensors are not
trained following a tire rotation, this symptom will also be present. Advise the customer that on vehicles with
different front and rear tire pressures, the sensors must be trained as directed in the Owner's Literature.
This pinpoint test is intended to diagnose the following:
 Low air pressure in tire(s)
 Tire pressure sensor(s)
PINPOINT TEST D: TPMS INDICATOR ON SOLID AND MESSAGE CENTER (IF EQUIPPED) DISPLAYS LOW TIRE PRESSURE
D1 CHECK THE TIRE PRESSURE
 Using the Digital Tire Gauge, measure and record the air pressure in all 4 road tires.
 Adjust the air pressure for those found to be below the specification listed on the Vehicle
Certification (VC) label.

NOTE:If the vehicle has been stationary for more than 30 minutes, activate
each TPMS sensor. Refer to TIRE PRESSURE MONITORING SYSTEM
(TPMS) SENSOR ACTIVATION. The TPMS sensor does not transmit
when the vehicle is stationary.

 Verify system operation.
 Have the TPMS indicator and the message center (if equipped) warnings gone out?
Yes : The system is functioning normally, diagnosis is complete. INFORM the customer of correct
tire pressure maintenance as instructed in the scheduled maintenance guide and the Owner's
Literature.

1.Turn the ignition switch to the OFF position, then press and release the brake pedal.
2.Cycle the ignition switch from the OFF position to the RUN position 3 times, ending in the RUN
position.
3.Press and release the brake pedal.
4.Turn the ignition switch to the OFF position.
5.Turn the ignition switch from the OFF position to the RUN position 3 times, ending in the RUN position.
 The horn will sound once and the TPMS indicator will flash if the training mode has been entered
successfully. If equipped, the message center will display TRAIN LF TIRE.
6.Place the Tire Pressure Monitor Activation Tool on the LF tire sidewall at the valve stem. Press and
release the test button on the Tire Pressure Monitor Activation Tool. The horn will sound briefly to
indicate that the tire pressure sensor has been recognized by the SJB .
7.Within 2 minutes of the horn sounding, place the Tire Pressure Monitor Activation Tool on the RF tire
sidewall at the valve stem and press and release the test button to train the RF tire pressure sensor.
Fig. 16: Identifying Tire Pressure Monitoring System
Courtesy of FORD MOTOR CO.
8.Repeat Step 7 for the RR and LR tires.
The procedure is completed after the last tire has been trained. When the training procedure is complete,
the message center (if equipped) will display TIRE TRAINING COMPLETE.
For vehicles not equipped with a message center, successful completion of the training procedure will be
NOTE:It may take up to 6 seconds to activate a tire pressure sensor. During this
time, the Tire Pressure Monitor Activation Tool must remain in place at the
valve stem.
NOTEo not wait more than 2 minutes between training each sensor or the SJB
will time out and the entire procedure must be repeated.
For vehicles not equipped with a message center, successful completion of the training procedure will be
verified by turning the ignition switch to the OFF position without the horn sounding. If the horn sounds
twice when the switch is turned to the OFF position, the training procedure was not successful.
.Using the scan tool, locate the updated TPMS sensor identifiers trained to the SJB and document them on
the applicable warranty claim.
.If the sensors are being trained due to the installation of a new SJB , clear any DTCs and carry out the
SJB On-Demand Self Test.
PRESSURE MONITORING SYSTEM (TPMS) SENSOR ACTIVATION
Tool(s)
CIAL TOOL SPECIFICATIONS
.Turn the ignition switch to the ON position.
NOTE:This step is required to clear DTC C2780, cause the SJB to exit the
manufacturing mode and to make sure there are no other concerns with a
newly programmed SJB .
Activation Tool, Tire Pressure Monitor
204-363, or Customer Activation Tool, Tire
Pressure Monitor
TE:The tire pressure sensors will go into a "sleep mode" when a vehicle is
stationary to conserve battery power. The sensors do not transmit information
while in sleep mode. It will be necessary to wake them up so they will transmit
the latest tire pressure information.

2.Position the Tire Pressure Monitor Activation Tool against the LF tire sidewall at the tire valve stem.
3.Press the test button on the Tire Pressure Monitor Activation Tool to activate the sensor. Activate the
sensor at least 2 times.
4.Repeat Steps 2 and 3 for the remaining tires.
5.If the Tire Pressure Monitoring System (TPMS) indicator remains illuminated after adjusting and
activating each sensor, refer to the SYMPTOM CHART.
NOTE:The Tire Pressure Monitor Activation Tool will provide feedback in the
form of a flashing green light and a beep sound for each successful
response from a tire pressure sensor. This feedback may not always be
present, do not rely on it as a confirmation that the module heard a
particular sensor.
NOTE:If a sensor does not respond to the Tire Pressure Monitor Activation Tool,
move the vehicle to rotate the wheels at least one-fourth of a turn and
attempt to activate the same sensor again. If the sensor still does not
respond, attempt to activate the same sensor again using the customer
activation tool (if available). If the sensor still fails to train, attempt to train
the sensor with the vehicle doors open.

 

WOW! The TPMS sounds like a royal pain in the rear. Hopefully there is a lamp that can be removed on the idiot light.

I prefer the MTPMS...M standing for Manual...Me and the tire gauge...fully Y2K compatable and EMP safe as well.

 

I too like the manual system but I also expect something to work as advertised. I expected that a 10 -15% loss in pressure would have triggered the alarm. I am dismayed that a 30% loss of pressure didn't trigger it. I think Chevy has it right showing the pressures in each tire and let the driver decide.

 

i had a flat, and the only message was low tire pressure it did not say wich tire was flat, this was a easy one as the flat was easy to see, but only a low pressure alarm would make you check all 4 tire? i have nitrogen fill tire.
2010 5.4L XLT.
Is there a way to find wich tire is low?
Thanks
Patgadget