Tire Pressure Low is on after I put on bigger tires?
So I switched from 235 70 r16 to 255 70 r16.. Now it constantly says I have low tire pressure. Any Ideas how to reset this, or fix the problem?
Im not sure, but I'd like to know to incase this happens to me when I put new tires on mine.
Indirect Tire Pressure Monitoring System do not use physical pressure sensors. Indirect TPMS measure the "apparent" air pressure, by monitoring individual wheel rotational speeds, and other signals available outside the tire itself. Most indirect TPMS use the fact that an under-inflated tire has a slightly smaller diameter than a correctly inflated tire and therefore has to rotate at a higher angular velocity to cover the same distance as a correctly inflated tire. Newer developments of indirect TPMS can also detect simultaneous under-inflation in up to all four tires using vibration analysis of individual wheels or analysis of load shift effects during acceleration and/or cornering, which can be realized in software using advanced signal processing techniques. However, the vibration analysis technique requires the use of additional suspension sensors which result in increased complexity and cost of the overall system as long as vertical chassis movements are concerned. That is why most current advanced indirect systems use the spectral content of the wheel speed sensor signals so no additional sensors are needed and the computations can also be carried out by usual processors for example in usual ABS or ESC control units.
If this helps any it is a post I found on wiki about how these things work.. I could understand with smaller tires but why with bigger? I have the same rims just a larger tire on them? Not sure why its doing this.
It might be a problem with one of the tires. I got new tires put on my '07 this summer, was fine the first couple of weeks, then the tire pressure light came on. I'd put air in it and again a couple of weeks later the light would be on again...turned out to be a problem with one of the tires...once they replaced that tire I haven't had a problem since.
Well now it is saying tire sensor error.. and my tire gauge flashes.. Then it goes back to tire pressure low.. Its weird because it switches back and forth randomly
Have you "retrained" them since you changed tire sizes? The only thing I have the TPMS on is my '08 E250 (thank goodness) and I have to retrain them after every tire rotation since the front and reat pressures are different.
I've checked your profile and posts and you don't say what year Trac you have. :scratch: That would help us help you. :yes:
From the FORD Service Manual:
Principles of Operation
NOTE: The Smart Junction Box (SJB) is also referred to as the Generic Electronic Module (GEM).
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 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 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. The instrument cluster then illuminates the TPMS indicator and displays the appropriate message(s) in the message center (if equipped).
For vehicles with different front and rear tire pressures (such as the E-Series and certain F-Series), the tire pressures must be adjusted and the tire pressure sensors must be trained following a tire rotation. Failure to train the sensors will cause the TPMS indicator to illuminate.
For vehicles with the same tire pressures for front and rear tires, tire rotation will not affect the system.
Ambient Temperature Change and Tire Pressure
WARNING: The tire pressure monitoring system (TPMS) sensor battery may release hazardous chemicals if exposed to extreme mechanical damage. If these chemicals contact the skin or eyes, flush immediately with water for a minimum of 15 minutes and get prompt medical attention. If any part of the battery is swallowed, contact a physician immediately. When disposing of TPMS sensors, follow the correct procedures for hazardous material disposal. Failure to follow these instructions may result in serious personal injury.
Tire pressures fluctuate with temperature changes. For this reason, tire pressure must be set to specification when tires are at outdoor ambient temperatures. If the vehicle is allowed to warm up to shop temperatures, and the outside temperature is less than shop temperature, the tire inflation pressure must be adjusted accordingly.
If the tires are inflated to specification at shop temperatures, and the vehicle is moved outdoors when the outdoor ambient temperature is significantly lower, the tire pressure may drop enough to be detected by the TPMS and activate the TPMS warning lamp.
As the ambient temperature decreases by 6°C (10°F), tire pressure decreases 7 kPa (1 psi). Adjust the tire pressure by 7 kPa (1 psi) for each 6°C (10°F) ambient temperature drop as necessary to keep the tire at the specified Vehicle Certification (VC) label pressure.
Inspection and Verification
NOTE: The tire pressure sensors are not designed to be used with aftermarket wheels.
NOTE: The use of run-flat tires (tires with steel body cord plies in the tire sidewall) where not originally equipped, may cause the TPMS to malfunction and is therefore not recommended.
Verify the customer concern by inspecting the vehicle and observing the message center (if equipped) and the TPMS indicator.
NOTE: The valve-mounted TPMS sensors and the strap-mounted TPMS sensors are not compatible. Swapping wheels from one vehicle to another with the different systems will set a TPMS fault.
NOTE: Swapping wheels between vehicles with the same TPMS will cause a TPMS fault to be set if the sensors are not trained. Refer to Tire Pressure Monitoring System (TPMS) Sensor Training in this section.
NOTE: Non-OEM modifications made to the vehicle may result in false TPMS warnings.
Inspect to determine if one of the following mechanical or electrical concerns apply:
I have a 08 V-6.. How do you go about training the tires? Will I have to take it into the shop for this?
Wow, I actually just went back and read the manual reference I just posted and it doesn't give instructions for resetting them. :thumbsdown: Get yourself a reset tool and I'll post the instructions from the Ford manual.
I didnt get one of those reset tools.. If I ordered that one off ebay.. would it work?.. The 2008 manual dont say how to use it though.. I checked mine and the one online. Im about to check the 07 model just to see
I saw the guide in the e250 manual but not in any sport trac manual... Ill have to try the sequence for the e250 and see if it works
SECTION 204-04: Wheels and Tires 2007 Explorer/Mountaineer/Explorer Sport Trac Workshop Manual
GENERAL PROCEDURES Procedure revision date: 02/26/2009
Tire Pressure Monitoring System (TPMS) Sensor Training
NOTE: If the vehicle has been stationary for more than 30 minutes, the sensors will go into a "sleep mode" to conserve battery power. It will be necessary to wake them up so they will transmit the latest tire pressure information to the Smart Junction Box (SJB). For additional information, refer to Tire Pressure Monitoring System (TPMS) Sensor Activation in this section.
NOTE: The tire pressure sensor training procedure must be done on a single vehicle, in an area without radio frequency noise and at least 1 m (3 ft) away from other vehicles equipped with a Tire Pressure Monitoring System (TPMS).
Radio frequency noise is generated by electrical motors and appliance operation, cellular telephones, remote transmitters, power inverters and portable entertainment equipment.
NOTE: If a sensor does not respond to the Tire Pressure Monitor Activation Tool, attempt to activate the same sensor with the Tire Pressure Monitor Activation Tool. If the sensor still does not respond, move the vehicle to rotate the wheels at least one-fourth of a turn and attempt to activate the same sensor again.
NOTE: The SJB has a 2-minute time limit between sensor responses. If the SJB does not recognize any 1 of the 4 tire pressure sensors during this time limit, the horn will sound twice and the message center (if equipped) will display TIRE NOT TRAINED REPEAT and the entire procedure must be repeated.
NOTE: For vehicles with different front and rear tire pressures (such as the E-Series and certain F-Series), the tire pressure sensors must be trained following a tire rotation. Failure to train the sensors will cause the TPMS indicator to illuminate. For vehicles with the same tire pressure for front and rear tires, tire rotation will not affect the system.
Turn the ignition switch to the OFF position, then press and release the brake pedal.
Cycle the ignition switch from the OFF position to the RUN position 3 times, ending in the RUN position.
Press and release the brake pedal.
Turn the ignition switch to the OFF position.
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.
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 180 degrees from the valve stem.
Place the Tire Pressure Monitor Activation Tool on the LF tire sidewall opposite (180 degrees) from 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
Within 2 minutes of the horn sounding, place the Tire Pressure Monitor Activation Tool on the RF tire sidewall opposite (180 degrees) from the valve stem and press and release the test button to train the RF tire pressure sensor.
NOTE: Do not wait more than 2 minutes between training each sensor or the SJB will time out and the entire procedure must be repeated.
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 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.
Go back to the shop who mounted your tires. They have to fix it. A sensor could have gotten damaged while they unmounted the originals (happens quite often I hear?).
Im going to have to look into this also, with the new larger tires on mine I keep getting a "tire sensor error" everytime I crank my truck. I have to take my ST in anyways for a recall (ya'll might want to look into that if you havent heard of it yet, its got to do with the shifter)