TPM system question

[Radioman]

The Ranger must not though cause I let air out in the garage with the key on and the pressure dropped.

If the sensors transmitted all the time, the batteries would not last very long. I don't know how long they send a signal after they stop turning.

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[MountainGoat]

If the sensors transmitted all the time, the batteries would not last very long. I don't know how long they send a signal after they stop turning.

I guess it's the key on that's activating them. I go out there and let some air out with the ignition on, display on to tire pressure.

 

[airline tech]

Being that there is a lot of confusion on exactly how the TPMS sensors work / wake-up.
The manuals point to - rotation must be sensed for it to wake-up if it has entered sleep mode.
so yes, it will go to sleep to conserve battery life.

Sorry, but the service manuals are poorly written and are not precise on how the sensors work.

Wake-Up possibilities:

1. When you turn ignition on you are powering the RTM and BCM, this MAY be providing the wake-up signal to the sensors.

2. If you adjust air pressure by about (5-PSI) this should wake them up

3. If you do not see any immediate change in tire PSI after adjusting, then drive it to 20 MPH for a few minutes and check the dash reading. You should now be seeing the refreshed pressure. So, lets change this to you MAY have to drive to a speed of 20 MPH to get an accurate reading.

4. I know that the sensors go to sleep, or their battery life would be very short, so I will say that the sensor goes to sleep along with the rest of the modules on the truck, and when you actuate the door locks or turn the key or open a door you are providing a wake up signal to various modules in the anticipation of a truck to be started.
We know for a fact that the RTM and BCM have received a wake-up signal at this point, but the question remains, does the RTM send a radio signal out to the TPMS sensor to wake it up, or does it take tire rotation to do it.
So, to be clear, the sensor wake up will provide a current PSI reading (Refreshed)
The sensors go to sleep from inactivity (No Rotation), or possibly they time out after the RTM goes to sleep and the TPMS sensor sees the signal is not being received (Communication.)

5. TPMS sensor will enter sleep mode after 30 minutes of inactivity (stationary)

Tire-Rotations and self-learn new position.

Being that I got out of Automotive before the TPMS became a thing, this one I have to rely on the manuals. (Not always a good resource)

1. We know that the sensors transmit PSI information, and the RTM (Radio Transceiver Module) will receive the radio frequency from the sensors and send the information along to the BCM.

2. We know that each sensor has its own unique radio frequency it will transmit.

3. Position Ident - The BCM has the Radio Freq stored in memory for current position of each sensor and has been trained to monitor that sensor say LF.

4. The manuals say nothing about the truck having the ability to relearn a new position when the sensor has been rotated to a new position, but this appears to be true by owners. It will relearn the new position - (Without human interaction-Sensor Relearn Procedure)
A test for this is: Using a Scanner before the sensor is moved and reading current positions of sensors, then rotate the tires and then repeat process with the scanner and note if the sensors have moved to the new position.
This MAY take the drive cycle of 20 MPH for it to happen.

Wheel Swaps

This is yet another area where the manuals give you the only option is to perform a sensor calibration as the description of the system the BCM can only retain (4ea) sensor IDs with no room or indication for the spare (if you have added a TPMS to it)

1. So, if you buy a extra set of Rims / Tires and swap them out, you now have a completely new set of sensors on the truck, per the manual you must treat this as a newly installed sensor and perform a sensor calibration (This is programming the RTM and BCM to recognize the new radio frequency)

2. So, if owners are reporting that no human input is required to get the new swapped sensors to work then this tells me that the RTM is looking for (ANY) radio frequency being transmitted.
Any it will pick up and learn the position via Proximity sensing.
Proximity Sense - Distance from the RTM (Radio Transceiver Module) above your head in the Headliner to each individual sensor, and I would say it is probably frequency strength it is looking at.
Note: The RTM is the same module that allows keyless entry for the door locks, remember this is also distance operated.

So, again if you have changed / swapped in new sensors, the truck (MAY) need to be driven to a speed of 20 MPH to read the new sensors.
I feel that this is actually (WILL) need, to get the truck to see them as being a new frequency ID.

If the above does not work then the Sensor Calibration or Learn procedure will need to be performed, so the truck can see the nw sensor frequency ID's

 

[Radioman]

Being that there is a lot of confusion on exactly how the TPMS sensors work / wake-up.
The manuals point to - rotation must be sensed for it to wake-up if it has entered sleep mode.
so yes, it will go to sleep to conserve battery life.

Sorry, but the service manuals are poorly written and are not precise on how the sensors work.

Wake-Up possibilities:

1. When you turn ignition on you are powering the RTM and BCM, this MAY be providing the wake-up signal to the sensors.

2. If you adjust air pressure by about (5-PSI) this should wake them up

3. If you do not see any immediate change in tire PSI after adjusting, then drive it to 20 MPH for a few minutes and check the dash reading. You should now be seeing the refreshed pressure. So, lets change this to you MAY have to drive to a speed of 20 MPH to get an accurate reading.

4. I know that the sensors go to sleep, or their battery life would be very short, so I will say that the sensor goes to sleep along with the rest of the modules on the truck, and when you actuate the door locks or turn the key or open a door you are providing a wake up signal to various modules in the anticipation of a truck to be started.
We know for a fact that the RTM and BCM have received a wake-up signal at this point, but the question remains, does the RTM send a radio signal out to the TPMS sensor to wake it up, or does it take tire rotation to do it.
So, to be clear, the sensor wake up will provide a current PSI reading (Refreshed)
The sensors go to sleep from inactivity (No Rotation), or possibly they time out after the RTM goes to sleep and the TPMS sensor sees the signal is not being received (Communication.)

5. TPMS sensor will enter sleep mode after 30 minutes of inactivity (stationary)

Tire-Rotations and self-learn new position.

Being that I got out of Automotive before the TPMS became a thing, this one I have to rely on the manuals. (Not always a good resource)

1. We know that the sensors transmit PSI information, and the RTM (Radio Transceiver Module) will receive the radio frequency from the sensors and send the information along to the BCM.

2. We know that each sensor has its own unique radio frequency it will transmit.

3. Position Ident - The BCM has the Radio Freq stored in memory for current position of each sensor and has been trained to monitor that sensor say LF.

4. The manuals say nothing about the truck having the ability to relearn a new position when the sensor has been rotated to a new position, but this appears to be true by owners. It will relearn the new position - (Without human interaction-Sensor Relearn Procedure)
A test for this is: Using a Scanner before the sensor is moved and reading current positions of sensors, then rotate the tires and then repeat process with the scanner and note if the sensors have moved to the new position.
This MAY take the drive cycle of 20 MPH for it to happen.

Wheel Swaps

This is yet another area where the manuals give you the only option is to perform a sensor calibration as the description of the system the BCM can only retain (4ea) sensor IDs with no room or indication for the spare (if you have added a TPMS to it)

1. So, if you buy a extra set of Rims / Tires and swap them out, you now have a completely new set of sensors on the truck, per the manual you must treat this as a newly installed sensor and perform a sensor calibration (This is programming the RTM and BCM to recognize the new radio frequency)

2. So, if owners are reporting that no human input is required to get the new swapped sensors to work then this tells me that the RTM is looking for (ANY) radio frequency being transmitted.
Any it will pick up and learn the position via Proximity sensing.
Proximity Sense - Distance from the RTM (Radio Transceiver Module) above your head in the Headliner to each individual sensor, and I would say it is probably frequency strength it is looking at.
Note: The RTM is the same module that allows keyless entry for the door locks, remember this is also distance operated.

So, again if you have changed / swapped in new sensors, the truck (MAY) need to be driven to a speed of 20 MPH to read the new sensors.
I feel that this is actually (WILL) need, to get the truck to see them as being a new frequency ID.

If the above does not work then the Sensor Calibration or Learn procedure will need to be performed, so the truck can see the nw sensor frequency ID's

I admire your knowledge and your willingness to share that knowledge to us. I, for one, really appreciate it and have saved many of your messages to further my understanding of the Ranger and its maintenance.

Having said that, two points on the above:
I don't believe the sensors in the tires receive, I think they only transmit.
I don't believe the sensors have different RF frequencies, I think each tire sensor has a unique code.

If I am in error, I apologize.

Again, I do appreciate your input.

 

[airline tech]

I admire your knowledge and your willingness to share that knowledge to us. I, for one, really appreciate it and have saved many of your messages to further my understanding of the Ranger and its maintenance.

Having said that, two points on the above:
I don't believe the sensors in the tires receive, I think they only transmit.
I don't believe the sensors have different RF frequencies, I think each tire sensor has a unique code.

If I am in error, I apologize.

Again, I do appreciate your input.

True, the sensor should be only send info - but I am trying to figure out how by decryption it only wakes up by rotation or a psi change greater than 5-PSI
If owners are reporting this to be happening without moving the truck then there has to be a way for the sensor to be woke up from the RTM (communication)
I think that if you are not performing any change to the PSI then the wake up will occur when the tire rotated.
If you add or release pressure, the sensor will wake up and indicate this change.
The main point and word here is (May) tire may need to be rotating to get a refreshed PSI

And
You are correct , the unique code would be imbedded with the frequency, for the location identification.

 

[Trustable]

You’ll have to activate/sync the tpm sensor in the new to you tire. Dealership may have to do or a tire shop. On my focus I didn’t have tpms on my winter tires but when I would take them off it would just display the tire pressure light all winter. When I put the regular tires on it would take a day then would sync up. That being said the Tpm on my focus would only alert if pressure was low, so not sure if it’s different in operation than the rangers.

 

[airline tech]

I did a quick little test and with truck sitting for 11 hours - I used Ford Pass TPMS readings from last update of them.
Read 34 Psi on all except LR at 33 PSI

Remote lock and unlock , open of door etc.
Put into Assy mode and read dash PSI
Matched the Ford Pass indications

Started truck same reading

Drove a block down the street reaching 20 MPH the indication for LR refreshed to 34 PSI
After a 17 mile trip , PSI now reads 35 PSI for LR and 36 for the rest

So this confirms that the sensor wake up is tire rotation, and I would assume that if I only adjusted my cold pressure by 1 to 2 PSI then it would take the same.
I am thinking that the 5 PSI variance will wake it as well.

And to clarify my above post - the sensor location is identified by the Radio ID of the sensor not distance - I knew that but got lost in thought for a moment.
Oh well I found my thought, that’s all that matters

 

[JACKSMYDOG]

Being that there is a lot of confusion on exactly how the TPMS sensors work / wake-up.
The manuals point to - rotation must be sensed for it to wake-up if it has entered sleep mode.
so yes, it will go to sleep to conserve battery life.

Sorry, but the service manuals are poorly written and are not precise on how the sensors work.

Wake-Up possibilities:

1. When you turn ignition on you are powering the RTM and BCM, this MAY be providing the wake-up signal to the sensors.

2. If you adjust air pressure by about (5-PSI) this should wake them up

3. If you do not see any immediate change in tire PSI after adjusting, then drive it to 20 MPH for a few minutes and check the dash reading. You should now be seeing the refreshed pressure. So, lets change this to you MAY have to drive to a speed of 20 MPH to get an accurate reading.

4. I know that the sensors go to sleep, or their battery life would be very short, so I will say that the sensor goes to sleep along with the rest of the modules on the truck, and when you actuate the door locks or turn the key or open a door you are providing a wake up signal to various modules in the anticipation of a truck to be started.
We know for a fact that the RTM and BCM have received a wake-up signal at this point, but the question remains, does the RTM send a radio signal out to the TPMS sensor to wake it up, or does it take tire rotation to do it.
So, to be clear, the sensor wake up will provide a current PSI reading (Refreshed)
The sensors go to sleep from inactivity (No Rotation), or possibly they time out after the RTM goes to sleep and the TPMS sensor sees the signal is not being received (Communication.)

5. TPMS sensor will enter sleep mode after 30 minutes of inactivity (stationary)

Tire-Rotations and self-learn new position.

Being that I got out of Automotive before the TPMS became a thing, this one I have to rely on the manuals. (Not always a good resource)

1. We know that the sensors transmit PSI information, and the RTM (Radio Transceiver Module) will receive the radio frequency from the sensors and send the information along to the BCM.

2. We know that each sensor has its own unique radio frequency it will transmit.

3. Position Ident - The BCM has the Radio Freq stored in memory for current position of each sensor and has been trained to monitor that sensor say LF.

4. The manuals say nothing about the truck having the ability to relearn a new position when the sensor has been rotated to a new position, but this appears to be true by owners. It will relearn the new position - (Without human interaction-Sensor Relearn Procedure)
A test for this is: Using a Scanner before the sensor is moved and reading current positions of sensors, then rotate the tires and then repeat process with the scanner and note if the sensors have moved to the new position.
This MAY take the drive cycle of 20 MPH for it to happen.

Wheel Swaps

This is yet another area where the manuals give you the only option is to perform a sensor calibration as the description of the system the BCM can only retain (4ea) sensor IDs with no room or indication for the spare (if you have added a TPMS to it)

1. So, if you buy a extra set of Rims / Tires and swap them out, you now have a completely new set of sensors on the truck, per the manual you must treat this as a newly installed sensor and perform a sensor calibration (This is programming the RTM and BCM to recognize the new radio frequency)

2. So, if owners are reporting that no human input is required to get the new swapped sensors to work then this tells me that the RTM is looking for (ANY) radio frequency being transmitted.
Any it will pick up and learn the position via Proximity sensing.
Proximity Sense - Distance from the RTM (Radio Transceiver Module) above your head in the Headliner to each individual sensor, and I would say it is probably frequency strength it is looking at.
Note: The RTM is the same module that allows keyless entry for the door locks, remember this is also distance operated.

So, again if you have changed / swapped in new sensors, the truck (MAY) need to be driven to a speed of 20 MPH to read the new sensors.
I feel that this is actually (WILL) need, to get the truck to see them as being a new frequency ID.

If the above does not work then the Sensor Calibration or Learn procedure will need to be performed, so the truck can see the nw sensor frequency ID's

I don't know if it's in the manual, but you need to drive about 20 miles (distance not speed) for the truck to pick-up the new sensors. You may also need to reach a speed of 20mph to wake them, I've never tested that, but distance is key to getting the truck to remember the new sensors.

I had to look it up after one of my rotations and a few days of very short trips. After a few miles the truck would appear to have the new TPMS connected, but then revert back to the old ones for the next day.

 

[airline tech]

I don't know if it's in the manual, but you need to drive about 20 miles (distance not speed) for the truck to pick-up the new sensors. You may also need to reach a speed of 20mph to wake them, I've never tested that, but distance is key to getting the truck to remember the new sensors.

I had to look it up after one of my rotations and a few days of very short trips. After a few miles the truck would appear to have the new TPMS connected, but then revert back to the old ones for the next day.

Cool thanks for the info.
So, a summary

Sensors go to sleep after 30 minutes of non-movement (Rotation)
Sensors can be woken up by altering air pressure by about 5 PSI or driving for 2 minutes at 20 MPH

New or added sensors (such as wheel swaps, summer / winter)
Sensors will activate after a 20-mile drive above the speed of 20 MPH. (Estimated)

Note: The Service Manuals, tell you to manually perform any sensor relearn or calibration with a tool or alternate manual procedure without the tool.
However, it appears the truck and the technology is smarter than the manuals lead you to believe.
So, our Rangers have the Yogi Bear capability and can perform this function on its own.

 

[Radioman]

Cool thanks for the info.
So, a summary

Sensors go to sleep after 30 minutes of non-movement (Rotation)
Sensors can be woken up by altering air pressure by about 5 PSI or driving for 2 minutes at 20 MPH

New or added sensors (such as wheel swaps, summer / winter)
Sensors will activate after a 20-mile drive above the speed of 20 MPH. (Estimated)

Note: The Service Manuals, tell you to manually perform any sensor relearn or calibration with a tool or alternate manual procedure without the tool.
However, it appears the truck and the technology is smarter than the manuals lead you to believe.
So, our Rangers have the Yogi Bear capability and can perform this function on its own.

Saved for future reference.. Thanks

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