rmorrow — I agree with your reading of the TSB. I am amending my post to correct this error. Thanks.

Stan

 

Good data! The tire pressure monitor is irrelevant to the key fob discussion, except that it is another of the automated RF transmissions in the car.

This does confirm that the door and trunk lock/unlock SmartKey automated functions via the 134.2 kHz query initiated by the car every quarter second when the car is locked, or after the trunk latch is depressed, or after the start button is pressed, and responded to by the fob on 312.315 MHz. That is, this is NOT Bluetooth, as I had thought.

This does NOT confirm the remaining two modes of RF communications used by the fob: 1) the much longer distance "Remote" (i.e., not SmartKey functions) fob communications for lock/unlock/alarm initiated by pressing a fob button, and 2) the RFID used at extremely short range when the fob battery is dead.

-- Alan

 

I believe it does, at least for the "Remote". The bullet giving the 312-315 mHz frequencies is headed "Smart Key Transmitter/Wireless Remote (communication from key to vehicle). I take the "Wireless Remote" to refer to all of the button-press functionality. What still remains unclear to me is the RFID functionality.

 

I think you misunderstand what the document says. I see nothing in the specification chart where any cell refers to the fob buttons (lock, unlock, trunk, alarm). Since there is no reference to these fob initiated functions, I assumed that the "Smart Key" and the "remote key" functions are separate. They may be on the same frequencies, but not necessarily.

To be clear, I believe the Smart functions are initiated by the car (the first RF signal) and responded to automatically by the fob. The car initiated functions may be every quarter second for the front doors open, or only after the trunk latch is pressed for the trunk, or only after the exterior door handle lock buttons are pressed for the door lock, etc., but the first RF signal for each function is sent by the car.

On the other hand, normal remote key fobs have buttons that initiate a transmit signal, which are received and acted on by the car without any RF reply.

For security reasons, I assume the Smart functions (where the RF is initiated by the car and responded to automatically by the fob) are at far lower power levels (to insure the range is short) than is the fob initiated RF link. There are a number of security reasons I can think of that the auto-respond signals need to be shorter range.

I'm not sure where I was misled to believe the Smart functions were using the Bluetooth protocols (perhaps my car salesman ), but this document Stan found is very clear that they are not Bluetooth.

-- Alan

 

Well, I suppose we can dance around this for a while, since the documentation is rather vague on that point. I still think that "Wireless Remote" refers to the human-initiated remote functionality on the fob. Otherwise, why wouldn't they just stop at "Smart Key Transmitter"? That already says it all as far as the fobs responses to the car. No, I think that it is meant to specifically include the remote control features.

Anyone out there have a mHz RF spectrum analyzer that wants to take a look? I'm afraid I sold mine a few years back.

 

To resolve this issue, I have just used an RF spectrum analyzer to measure the fob's RF transmissions when its buttons are pressed. They are in the 314 MHz region, which agrees with the TSB's statement that the fob uses the 312-315 MHz frequency range for Smart Key and Wireless Remote functions. It thus seems that it uses the same frequency band for its key-press functions too. The RF power is undoubtedly also higher for those functions than it is for the short-range Smart Key functions. The modulation scheme is likely also different, but my experiment didn't try to ascertain anything about these.

Stan

 

Thanks!

-- Alan

 

I think that the poor wording of TSB EL015-06 has thrown some of us off in our original interpretations. The only part of the whole TSB that deals with fob-to-car communications is its very last sentence:
"Smart Key Transmitter/Wireless Remote (communication from key to vehicle): Frequency: 312-315 MHz"
[Actually, it says mHz (millihertz), but this is clearly wrong. They mean megahertz (MHz).] This clearly indicates, as pointed out by rmorrow, that it applies to both Smart Key operations as well as button-push communications. All the rest of the TSB refers only to car-to-fob communications, as the first line of page 2 says:
"Smart Key Antenna (communication from vehicle to key)."

Stan

 

Yay. I win. Sorry. Couldn't resist. Thanks for that, Stan. Now I can sleep again.

 

Yeah, I saw that too, but I was afraid to throw that into the mix and further confuse the issue.