Looking for updates to this thread from our current forum experimenters!

 

I have seen both 315 and 433 listed for freq's on the replacement part #'s. Do you know what freq. the Crossie is?

 

Hi Frank, can you get us the numbers off them? Seems we have two frequency's. I would have to get mine then know yours to see if we have a match.

 

The Crossfire uses both, I think that the 433Mhz is used mainly in the '05s.
Use the ones noted above by Schrader, they seem to work.
20028's (315Mhz) work and hopefully the 20066's (433Mhz).
I think that's the correct MHz assignment to part number - check it though.
See post one for the OEM part numbers and the replacement number.

 

Please note the P/N shown and frequency shown.. for our 2005 roadster.. and my 04 coupe has been read as 433mhz by discount tire.

 

TY! Actually this was a premature post, I usually read the entire thread to make sure it isn't addressed later in the thread and sure enough I saw it later. OH and I have RF gear, I wonder how strong the signal would be and it probably does not start until we hit 20MPH like the manual says.

 

It has been a month, is the light still out after the 50 PSI then turn car off then reset to 36 PSI?

 

Straight from the book.....

STANDARD PROCEDURE - TPM MODULE PROGRAMMING
If a TPM module fails, or one or more tire pressure sensor/transmitters fail, the TPM module’s diagnostic memory must be cleared and reprogrammed after replacement. This is necessary for the module to detect which wheel is sending the signal.
Refer to the following procedure to program the module for identification of tire pressure sensor/transmitters.
Note: The vehicle’s tires must not have been rotated above 8 km/h (5 MPH) in the last two minutes prior to programming.
1. Connect a DRB III􏰂 scan tool to the vehicle’s diagnostic connector beneath the instrument panel near the steer- ing column.
2. Access the Chassis System using the DRB III􏰂. 3. Once in the Chassis System; select Tire Pressure Monitor, then select Miscellaneous Functions. 4. Select Train All Mode from the System Test screen displaying the following options:
• Tire Set • Train All Mode • Stop Train Mode
5. Place the magnet, Special Tool 8821, at the valve stem for that wheel as directed by the DRB III􏰂. 6. When each wheel’s pressure sensor/transmitter has been programmed, the DRB III􏰂 will automatically direct you
to the next wheel sensor/transmitter to be programmed.
Note: When programming the module (all four sensor/transmitters), the magnet should be moved from wheel to wheel in a clockwise direction starting at the left front wheel.
7. Remove the magnet and move to each of the remaining wheels as directed by the DRB III􏰂. Each sensor/trans- mitter will automatically sense the presence of the magnet and begin programming.
8. Once “Training Completed” is displayed, exit the program function screen. 9. Verify that the module programming is complete by looking at the tire pressure sensor/tire pressure readings in
the Sensor Display using the DRB III􏰂. 10. Once programming is complete, select Stop Train Mode from the System Test screen.

 

Who knows, it might be one of those little secrets that very few people know about. Or does it damage the transmitter forward? Here is a scenario... People take their cars in to have the TPMS light taken care of, tech does this mumbo-jumbo and when your called, a whopping bill confronts you. You pay it (because you want your car back) and drive happily ever after (until the next glitch)...


I would just do the TPMS disconnect at the module near the dome light. I check my tires occasionally, as I don't trust some things to little pressure sensors that do not have replaceable batteries in them (not to mention the cost to dismount/replace and such). Just another money pit that generates big bucks for mechanics, and just as useless as a dealership with an untrained XF tech replacing parts until you go away (type of troubleshooting style).

 

This is all well and good but in many areas you will find that the safety test will be failed if the sensors are not working. If the car comes with them as OEM equipment they must work. Presumably they can tell if they are working. No safety check here in Ontario prior to sale and the car cannot be sold privately as a roadworthy vehicle. Presumably dealers would have to get it fixed.

 

?? Say Whaaaaaat? Never have I seen a TPMS check at any vehicle registration checkpoint (emissions check). If some state has this rqmt I definitely will never register a vehicle there as you can get ridiculous when it comes to squeezing monies out of taxpayers for really dumb stuff. The huge majority of pollution is natural or industrial made yet the little guy winds up being legislated the most. I just bing'ed this stupid requirement and found 4 US states require a TPMS system to be tested and operational ( Hawaii, Rhode Island, Vermont and West Virginia have and check/verify proper TPMS function as part of the annual vehicle inspection. ). What idiots live there that elect representatives to allow these morons to stay in office?? Guess the help items in the forum that show how to disable, now has to have a really dumb disclaimer when the member lives in one of these states. Never ceases to amaze me how stupid bureaucrats and taxpayers can be... ??

 

Here is the FCC data sheet on those sensors. Are these magnet induced transmit or LF 125Khz induced transmit?

FCC ID MRXGME54A4 by Schrader Electronics for Tire Pressure Monitor Transmitter (MRX-GME54A4, MRX GME54A4)

 

I'm not sure why these little things give techs soooo much trouble.

Upon further investigation it looks like we have two frequency bands they transmit on, 315 & 433Mhz. There are two ways to get them to transmit on cue, some transmit when a big magnet is near them (The Crossie has this type OEM) and the other type transmit when they receive a 125Khz signal.

They all transmit a unique identifier code along with the tire pressure/temp data per burst. The cars receiver is "trained" to listen only to it's sensors identifier codes and ignore any other identifier codes and associated data of nearby cars on the frequency. A parking lot or red light in city traffic has got to be congested frequency wise with all these bursts happening nearby.

So why all the trouble at tire shops?

Some replacement sensors are clone-able meaning they can be programmed to emulate the OEM existing sensors identifier code. This allows you to have two sets of wheels/tires and not have to reprogram the car to the new sensors when changing summer to winter. The car may have to know the location of the tire on the car but that process is real easy since the car already knows it's sensors to listen to but just needs the new location. The Crossfire does not have the location identifying type to the driver however the DRBIII will know.

Is this be why we get stuck between the dealer and the tire shop.....
Tire shop puts replacement sensor on of the 125Khz cue type then we take the car to the dealer and they are trying to use the magnet to get the sensor to "talk"? It aint gunna work.

We know the tire shop has zero access to the car computer so they better put on either the clone-able type and make the new one match the id code of the one they take off eliminating the need for a car reprogram or they need to put a mag cue type sensor of the proper frequency on so the dealer can trigger the thing to talk and sync to the car.

I highly doubt many tire shops have anyone technical enough to first understand the vehicle we have and then all of the TPMS variables out there.

 

"if" rims were swapped left to right at any point by a tire shop.. DRBIII will not have a clue as to which is where .. and doesn't care. I suspect enter and process in a clockwise motion is provided over "just ***** nilly pick the next one". It accepts 4 ID's and as long as they are present and functioning it is happy. And they do broadcast without moving. Ever air the tire up and notice the warning go out? Just like when car has sat and lost air.. no motion yet warning light will show.

 

I had Sparkies rear tires on my car once to pass a safety test and the light did not go on once. So maybe all the receiver needs to know is that the four signals are within the range.

 

I wish that were the case, I ran my SRT6 wheels on my NA for about a week before the light finally came on. I put the NA wheels back on and the light came off after a short drive.

 

I guess they were'nt on there long enough. I used the word maybe in my statement. You have to cover your @ss on this forum.

 

 

I read this in the service manual.....

"Each tire pressure sensor/transmitter has a unique identity code. This will allow the TPM system to indicate to a technician, through Diagnostic Trouble Codes (DTCs) in the module, which tire of the vehicle has lost air pressure. This code is also used to identify to a technician which pressure sensor/transmitter has set a DTC."

Makes it sound like the DRBIII can read the computer and tell which sensor had the error.

 

They have to have a unique identifier.