Info On Tire Pressure Monitoring Systems (TPMS) | Ford Explorer Forums - Serious Explorations

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Info On Tire Pressure Monitoring Systems (TPMS)

I had a class the other day for work, and it was all about the Tire Pressure Monitoring Systems coming out on newer vehicles. I found out a good amount of information. I wanted to share it with the 03-newer Explorer owners, because most newer Explorers-Mountaineers have the TPMS!

What's Covered In This Section:

1. Hard Facts (Sub-Categories: (a) Reasons Why)
2. Two Types Of TPMS (Sub-Categories: (a) Indirect, (b) Direct, (c) Old Fashion)
3. What/Who Uses What
4. How Do I Know I Have It
5. Changing Tires and Wheels
6. How Do They Relearn
7. Aftermarket Wheels and Tires

Hard Facts:

-- NHTSA - New proposed rule requires TPMS on all passenger vehicles, trucks, and buses with a GVWR of 10,000 pounds or less. (excluding duallys under 10,000 pounds)

-- 100% compliance is required by January 1, 2007 subject to phase in schedule: 20% by September 2005, 70% by September 2006, and 100% by Jan 2007.

Reasons Why:

-- The National Highway Traffric Safety Administration conduced an inspection of 6,240 vehicles within a 14-day period in August of 2001. Found that out of those vehicles tested, 27 percent of the passenger cars had one or more tires substantially under inflated. They also found that 33 percent of light trucks and suVs had one or more tires that were also under inflated.

-- About 8,000 blowouts every year result in serious injury or death.

Note: some TPMS check and warn about HIGH air pressure. The NHTSA mandated systems do not require high pressure warnings.

Two Types Of TPMS:

-- One type measures the pressure in the tire directly (Direct TPMS). The other checks tire pressure indirectly (Indirect TPMS) by testing the effects on the tire from the pressure change (i.e. - through the ABS system - wheel sensors).

Indirect TPMS:

By watching the wheel speed sensors, the ABS module "knows" how fast each wheel is turning. Two modes of operation while driving: Calibration and Detection. After tires are rotated or replaced, the "reset" button must be pressed to clear the prior saved calibration from its memory.

When the vehicle reaches a predetermined speed (or speeds) for the first time after resetting the system, it enters into its calibration mode.

- In this mode, it "learns" how fast the individual wheels are spinning. It also takes a sampling of those measurments and saves those values in memory. It cannot detect a low tire in calibration mode.

The indirect method does not satisfy the NHTSA's requirements and will not longer be on new model vehicles after 2006. Diagnostics of these types of systems should not be a problem for any shop that does ABS systems. Same type systems, senosors, electrical devices, etc.

Direct TPMS:


The only method that currently satisfies the NHTSA's requirements. It works by use of a radio trasmitter located inside the tire:


The radio transmitter is actually the valve stem's base. The valve stem is part of the transmitter and serves double duty as an anchor and as an antenna. If the vehicle is equipped with a spare, the spare will have a transmitter as well. The first direct TPM sensors (like found on some older Corvettes) were a rather large sensor (approx. 3 inches long, 2 inches high, and a inch wide).

The typical modern direct TPM sensor has a 10-year lithium battery that is not replaceable. The sensor weights just over one ounce. It's accurate up to 2 PSI of its reading, and have been tested over 200 MPH. they carry price tags in the low hundreds each (higher for BMWs, Lexus, etc.).

Transmitters/sensors are not constantly on. They only send a signal about every 30 to 60 seconds at speeds of 15 to 20 mph. then, when sitting still, they transmit a pressure reading about once each hour.

Every manufacturers system is different, and diagnosing and fixing these systems vary. should the module determine pressure to be too low, or fail to recieve a signal, the TPM light will illiuminate (on top of page) or will state so in message center. This INCLUDES the spare tire!

If a tire is low, and you inflate the tire, the light should go out (if that was the problem). However, if the tires are rotated, then most of these systems require retraining the sensors/modules. The TPM system "knows" the placement of each tire (LF, RF, RR, LF, and spare), the technician must retrain the module each time the wheel assemblies are rotated. Or if the tires are replaced and the rims are not put back in the origional positions.

Old Fashion/Aftermarket TPMS:


What/Who Uses What:

Indirect TPMS:

- Ford: 2001-03 Windstar
- GM : 97-02 Park Avenue, 99-03 Century and Regal, 02-03 LeSabre, 2003 Rendezvous and Aztek, 00-03 Impala and Mone Carlo, 99-02 Alero, 99-02 Grand Am, 01-03 Aurora, 97 Grand Prix, 2000-03 Bonneville
-Toyota: Sienna Van
-Nissan: Pathfinder

Direct TPMS

-Chrysler: 02-03 300M and Town&Country, 03 Viper, 04 Pacifica
-Ford: '03 Explorer and Mountaineer
-Lincoln: 03' Navigator

-GM: 00-03 Deville, 97-03 Corvette (as well as some older Corvettes)

How Do You Know I Have TPMS:

-If it is factory equipped with Extended Mobility tires (EMT, A.K.A. "runflats"), then it will have a pressure monitoring system. Runflats are required by federal law to have a TPMS -- and any store that will sell you Runfalts on a non-TPMS, will require you to buy new wheels/Sensors.

-You can tell by a simple turn of the key or a look at the valve stem. Turn the key on the ON position and look on the dash for a light. If the vehicle is equipped with navigation, go through the menu and search for the TPMS. If you look at the valve stem and it looks to be metal/aluminum, and locked in place by a nut, more than likely you have a TPMS.

Valve stem looks similar to this:


-Be sure to inflate tires to the pressures specified on the vehicles data plate, no more going by the rating on the tire.

Changing Tires and Wheels:

If you replace new tires, it is highly recommend to get a new grommet, seal, and o-ring set. Replacing these seals are about $10 in parts per wheel. Here's a diagram:


The TPM valve stem cap is made of aluminum and the valve core is nickel-plated for resistance of corrosion. The outer end of the valve stem functions as the sensor's RF antenna. Always place both the cap and the sensor/valve assembly on a clean, dry surface when they are removed from the wheel.


- If the metal stem cap is stuck, DO NOT use plies to remove it -- it will break!
- DO NOT use a self calmping air chuck on the TPMS sensors, valve stems will break off! These things are VERY fragile!
- Valve Cores of the TMPS are not the same as regular rubber stems, do not lose them.
- DO NOT replace cap with a rubber one, it will mess up the transmitters
- DO NOT use "fix-a-flat" with a TPMS; it will clog the sensor and render it broken.

How Do They Relearn?

Different manufacturers use different ways to relearn or retrain the TPMS! Some use magnets with a certain process and some use a "reset" button. Here are some pictures of the magnets that GM Uses:



Aftermarket Wheels and Tires:

This information is still up in the air. Some aftermarkte manufacturers are trying to make wheels that'll work with the sensors, but the problem is that the sensors are made to fit on the wheel a specific way (flush against the rim). If it does not sit flush, it may break off during normal operation. Most systems will allow you to change for bigger/smaller tires. The biggest problem right now is with low-profiles and these sensors.

Of coarse, I would like to hear some feedback, corrections, and opinions about all of this stuff. I hope this will help some people out. I can probably get the "relearn" steps for a Explorer/Mountaineer/Navigator if you all think I should.


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Great system... If I want it. I shouldn't be forced to pay for the stupidity of 8,000 people out of 50 million or so who drive every year WITHOUT having fatal blowouts.

TPMS Part number 2005 Explorer

I guess no one knows what the part number is for the tire sensor setup which attaches to the wheel?. I know the Ford dealer hasn't a clue... it's really frustrating. The system will mount to my aftermarket wheel according to the wheel manufacturer Plenty of clearance at the stem and flat surface area). Anyway, I guess I'll try talking to another forum and see if anyone out there can help me. Updated 8/27/05. :(

Does anyone know the part number for the complete TPMS? I have been to the dealer and ordered what I thought was the complete system (including the sensor) when the Parts Guy showed me what he received, it was the outer stem, valve cap, Outer sleeve with a rubber washer, and the internal valve stem... but no sensor. We looked again and according to the parts system it should have been included. I was told they would check and get back to me. So far, a couple of months later, still no word. If any one can tell me the part numbers for a complete system, I would be very appreciative. I need the TPMS for some aftermarket tires I bought. The old tires and rims will be used for winter driving. :D

Will the Ford Sensors even mount correctly to your aftermarket wheels? If they are "suppose to" tell us who makes the wheels. On the part number, I don't think you can get a part # for just the "system" -- it's for the sensors, transmitters, etc which all have seperate part numbers. Now for the sensors, a Ford dealer should be able to get you a sensor No Problemo!


Well, I finally had to deal with one. It was a 2005 Cheverolet Tahoe with about 3,200 miles on it. I got the job ticket and it said "Customer reports of a leak in the right rear". Well, I start to clock in on it and then I look at the top and notice it said 2005. Immediately, I remembered the other day when I had another '05 Tahoe with it's first oil change, it had the TPMS. One thing I also noticed, was that the spare DID NOT have a sensor. Most manufacturers have one in the spare as well. But here is the trick, they put them in full-size spares AND aluminum wheels -- not steel wheels. The spare had a normal rubber stem.

Anyway, I pulled the Tahoe in and first checked for a TPMS indicator lamp to be shown, but there wasn't one. I proceeded to remove the wheel from the vehicle and I soon found a puncture near the sidewall on the tread. I removed the air from the tire and then did the following:

1) Removed retaining nut from stem (usually a 12mm)
2) Allowed the sensor to fall to the bottom of the tire
3) Broke the beads like normal, but made sure the sensor was at the bottom of the tire.
4) Put the tire on the tire changer and raised one bead above the wheel. I then reached inside and pulled the sensor out completely so when bringing the other bead up, it will not damage the sensor.

That was it! It's really not as bad as they are making it sound. But there is some bad news, these O-rings and Grommets that seal these stems, are like Crush Sleeves for Pinions or Torque-Yield bolts...they seem to be only good once and that is it! This vehicle only had 3200 on it and it already had a damaged o-ring. I think that when they are installed, they are ruined in they are removed. The grommet was starting to peel. I did however re-use it and hoped for the best. Luckily it sealed up fine.

After I fixed the tire, I put the tire back on the wheel and before I sat the beads back, I put the sensor back, and put the retaining nut back on the stem and torque it to it's specifications (for this Tahoe it was 62 in. lbs, not ft. lbs). After that, I aired it up and went ahead. For a 05' Tahoe all tires need to be at 35 P.S.I. REGARDLESS of what the tire manufacturer says! GM even puts 44 p.s.i. tires on their vehicles that have TPMS of only 35p.s.i. -- it's strange! One more thing, I did not have to "re-train" the system afterwards (since I did not rotate)!

This is my first of MANY future expierences with TPMS. Just wanted to share. Good luck to anyone else who has to deal with them.


APC (The riceboy accessory company) makes an aftermarket TPMS that has sensors which strap the the inside of the wheel. I've seen it onsale for $250/kit, including 4 sensors, mounts, and the receiver.

Its pretty cool - untill you want to put on aftermarket wheels, tires, air down, air up. Then you'll have the thing yelling at you.

Yes, there was a picture in my origional post that showed the "old fashion" type TPMS. Here it is again:


You can see how it is strapped to the wheel. It is a nice system, but I'd only want it on my luxury vehicles, not my base models. I could see like Lexus, Mercedes, etc. having these systems, but only a few Domestic vehicles having it. That's the way I wish it was.


I'd like to vote this as a useful thread. I'm sure if I hadn't read this and had a car/truck with TPMS I would have trashed at least one valve stem through ignorance.

I have an 05 and it says nothing about "relearn" when you rotate the tires. Anyone know if I have to or does it do it itself?

I am going up to work tomorrow to do a few things, so hopefully I can look up the procedures for relearning the system. I believe Fords are mostly Magnetic. I will possibly print the procedures for everyone.


ffdemoss said:
I have an 05 and it says nothing about "relearn" when you rotate the tires. Anyone know if I have to or does it do it itself?

Found the information today (sorry it took me awhile - foregot all about it).

2005 Ford Truck Explorer

Sensor Training

The tire pressure sensor training prcedure must be done in an area without radio frequency (RF) noise. RF noise is generated by electrical motor and appliance operation, cell phones, and remote transmitters.

1. Turn the ignition switch to the OFF position
2. Turn the igntion switch to the RUN position three times, ending in the RUN position. Do not wait more than two minutes between each key cycle.
3. Press and release the brake pedal
4. Turn the ignition switch to the OFF position.


1- Left Front Tire
2- Right Front Tire
3- Right Rear Tire
4- Left Rear Tire

5. Turn the ignition switch from the OFF position to the RUN position three times, ending in the RUN position. Do not wait for more than two minutes between each key cycle.
6. The horn will sound once and the TPMS indicator will flash if train mode has been entered successfully. If equipped, the message center displays "TRAIN LEFT FRONT TIRE." Place the magnet on the valve stem of the LF tire pressure sensor. The horn will sound briefly to indicate that the tire pressure sensor has been recognized by the TPMS module.
7.Within two minutes after the horn sounds, place the magnet on the valve stem of the RF tire pressure sensor. NOTE: If the TPMS module does not recognize any one of the four tire pressure sensors during the tire training procedure, the horn will sound twice and the message center (if equipped) will display "TIRE TRAINING MODE INCOMPLETE." If this occurs, the entire procedure must be repeated from Step 1.
8. Repeat Step 7 for the RR and LR tires. When the tire training procedure is complete, the horn will sound once and the message center (if equipped) will display TIRE TRAINING MODE COMPLETE.

This should help. For now, probably all Fords are like this. And I do not believe that Ford puts sensors in their spares (some GMs do).


What happens for larger tires? For instance the 31x10.5 tires I had before needed about 40psi to do a chalk test correctly. If I used the stock rims then the sensors would be almost useless and might even complain about too much pressure.

Also what does the vehicle do if it can't contact the tires - i.e. you have aftermarket rims without sensors.

MattHarrell said:
What happens for larger tires? For instance the 31x10.5 tires I had before needed about 40psi to do a chalk test correctly. If I used the stock rims then the sensors would be almost useless and might even complain about too much pressure.

Also what does the vehicle do if it can't contact the tires - i.e. you have aftermarket rims without sensors.

Good questions. So far, MOST (so take this lightely), Tire systems do NOT have a high pressure sensor warning. It is strickly for low pressure. Now, some do have a high pressure setting, but I can't recall any that do.

The thing about TPMS is this -- they are all designed differently. Ford uses sensors on the wheels while some others use the ABS sensors/or similar to calculate tire pressure. But, with this in mind - Ford monitors the air directly in the tire - so circumfrence doesn't matter, air pressure does. So I think (but I could be wrong) a 50 PSI tire on a 30 PSI sensor would be ok (as long as there is no high pressure warning). Aftermarket wheels will make the sensors either go crazy or just blink at you all the time. Just like pulling all your ABS sensors, it'll acting totally different!


ExplorerDMB said:
But, with this in mind - Ford monitors the air directly in the tire - so circumfrence doesn't matter, air pressure does. So I think (but I could be wrong) a 50 PSI tire on a 30 PSI sensor would be ok (as long as there is no high pressure warning).

Yeah I can see it not complaining if there isn't a high pressure warning but then they're also useless for their intended purpose since they wouldn't start complaining until the tires had lost about 25 psi to make the "assumed" 30 psi tires low. Too bad you can't retrain them for a different pressure

Hey guys, new member here and I hope it's okay I'm here... I actually have an Expedition right now although I've had an Explorer before, does that count?
This is actually a very useful thread, if it's okay, before I'm done here I may copy and paste alot of this for elsewhere on the internet! I'm on most of the time, expedition & navigator pages...
Here's my question... I just put 20in Roush rims on my 2005 Expy equipped with the TPMS. They were not able to re-use the sensor/valve stems on the new rims/tires. So now, every time I get in the car, I have to reset the on-board display with the error message "TIRE PRESSURE MONITOR FAULT" kind of a PITA! As this thread evolves... does anyone knwo what I can do to correct this problem!
Here's a pic on my Expy w/my new rims...

Currently aftermarket companies are trying to make wheels compliant with the sensors used so that their wheels will be able to house the sensor. Now - I hope you kept the wheel sensors - if you didn't then thats a LOT of money thrown away. Also, You may look into other types of TPMS sensors that may run at a similar frequency of the stock ones, but I don't know if this would work or not. Call Ford and see what they have to say; if anything. Or ask them a way to dissable it -- it's not mandated yet (not until '07) so they should be able to dissable it (just like if it was fog lights, and you didn't want them or something similar). Good luck.


EDIT: nice truck and welcome! :thumbsup:

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Hey Drew,
Thanks for the quick response... I still have the factory 17's WITH the TPMS intact. Not sure if I'm gonna run these wheels/tires in the winter yet so I just left the others put together. And, as you kind of eluded to, the dealer is only moderately helpful. I have a guy at my local dealer that made some calls for me. But came up empty-handed dealing with Roush as these wheels do not have the area for the flat sensors. I did try to do some homework before I did this upgrade, but in the end, went ahead because I love the look! Just trying to figure out what I can do down the road. Kinda bummed by Roush, a Ford tuner company but has not addressed this yet!
I'll check back often!
BTW, thanks for the compliment! I love the way it came out.