Key transmitter?

One of my 2004-300M key transmitters doesn't seem to be working. The batteries are OK, but I can't get it to function on the car. Is there a way to determine if it's transmitting, before I chuck it for another.

Reply to
Josh S
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The dealer has a tool that all it takes is a push of your key fob and it will pick up the signal to see if it is putting out. more then likely your key fob is bad. Check to see that the contacts in the remote has not separated from the circuit board.

Glenn Beasley Chrysler Tech

Reply to
maxpower

Also, since you apparently have one working fob, you can go thru the programing routine using the good one, in case the non-working one just lost its code. Might be dirty battery contacts too.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

THX Glen.

I thought they must have such a device, but my dealer said they don't. They said all they could do is try to program it, a 30 minute minimum charge. I already did that myself, so no deal. This is a very good dealer. Perhaps I should try another dealer. I'll also check the battery contacts again.

Reply to
Josh S

Take a working key fob, go to an AM radio, tune the radio to static in between stations, put the keyfob next to the radio and press a button, you should hear a blast of static from the working transmitter. If you do not hear the same blast of static from the non-working keyfob, the fob is dead.

Ebay has lots of fobs.

Ted

Reply to
Ted Mittelstaedt

Reply to
man of machines

Reply to
Josh S

Go to AutoZone. On their counter they have a display that tests key fob transmitters.

Reply to
Pete E. Kruzer

I tried this. Tuned the receiver to 990 AM. Lots of static. I placed my PT fob next to it. Pressed it. Nothing. No change. And my fob transmitter works.

Reply to
Pete E. Kruzer

You are obviously mistaken. :)

Reply to
Bill Putney

OK I'll try that. Lots of radios here.

Reply to
Josh S

Ted; I tried the radio, but it didn't detect even the good transmitter. Have you a suggested radio frequency?

Reply to
Josh S

Any modern transmitter, like your key fob, generates it's radio signal digitally. (the actual signal itself is analog, but it's digitally generated up to the final stages) Also, the code itself is a digital code.

In any digital circuit there's lots's of squarewaves that make a nice harmonics, that splatter all over the radio frequency spectrum. Crappier AM radios, (like most of them) have poor shielding and discrimination circuits and can easily pick this electrical noise up. But, it is highly dependent on proximity and sensitivity since these harmonics don't have a lot of radiated energy behind them.

The test I outlined wasn't one that actually tested if a signal is present, but merely that the circuity in the fob was getting power, and actually doing something.

If you put your AM radio on top of a computer, monitor, or any other digital electronic device you would hear the same electrical noise - assuming the radio is sensitive enough to pick it up. It may not be. Or it may have noise rejection circuitry that filters it out. Or it may be in a huge empty case that gives many inches of empty air between the AM radio antenna and the case wall which would limit the proximity and signal pickup.

Per FCC specs, digital circuits aren't supposed to radiate a lot of energy anyway - as it causes intereference - so the manufacturers do what they can to attempt to limit it. That is why most computer cases are metal, and the ones that are plastic usually are spraypainted with a metallic silver on the inside of the case, since computers are terrible emitters of interference. I would be very surprised if a car keyfob which is designed for intermittent use only, would have any real shielding in it.

Ted

Reply to
Ted Mittelstaedt

So would I Ted. Must be too good a (Sony) radio I used, I'll try a lower quality radio. I thought you'd tried what you suggested and knew a possible frequency. BTW, I'm an electronics engineer who knows about radios, computers, etc.; your description was good.

Reply to
Josh S

BTW, I'm an electronics engineer who knows about radios, computers, etc.; =A0your description was good.

Josh and Ted, this should interest you.

formatting link

Reply to
Pete E. Kruzer

Hmm, I wonder if it works on cell phones too...

I do fault the analysis, however as they failed to take into account the enhanced radiation pattern of a female "built like a brick shithouse" I would think the additional surface area and positioning of the, er, "features" on the chest area would focus and concentrate the beam.

In addition they should have tried other positions than the chin - for example the calves, thighs, and groin - if you shoved the remote down your pants how much is the radiation pattern enhanced?

Ted

Reply to
Ted Mittelstaedt

Depends.

Reply to
Bill Putney

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