The FCC and modern cars

jeep
cherokee

#1

My Jeep Cherokee has a homelink, like most new cars have. I was coming home and as I neared my house I hit the button to open my garage door. It opened just fine; however, as I approached I noticed the driver’s side sliding door on my neighbor’s Dodge Caravan was also opening. I checked with him and he his keys were hung up by the door, high enough that his small daughter could not reach them. I know the FCC reserves certain frequencies for various uses (AM radio, FM radio, television, etc.). My garage door opener is relatively new, so it has the rotating codes that change with every use. Is it possible that my garage door and my neighbor’s Caravan operate within the same frequency range?


#2

You could sit in your driveway and try it. Get your neighbor in on the fun. He would certainly want to know if this happens. He can park the van on the driveway and you can punch the homelink button. If it does open the van door, take your Jeep to the dealer and explain the problem. Maybe they can reprogram the homelink to operate without doings no this. Insist that you pay nothing for the service.


#3

Don’t know if they use the same frequency band. But your remote may be miscalibrated such it “leaks” signal outside its assigned freauency band.


#4

Garage door openers made after 2005 use between 300 to 400 Mhz and have rolling codes. Vehicle remotes use 390 Mhz and also rolling codes. So it is possible that a one time operation opened the neighbors door. Apparently the chance of that happening again is slim.
Back before the rolling codes I put in a garage opener and set the numbers and actually matched it to one 4 houses away.


#5

It’s bound to happen. No system can be totally immune. Even keys. True story: back when I my '79 Toyota pickup was fairly new, I once walked up to a matching truck in a parking lot by mistake, unlocked the door, and realized when I looked inside that it wasn’t mine! I locked it back up and found mine, which was in a nearby space, slightly embarrassed.

There are simply far more of any popular vehicle model manufactured than there are code possibilities, even with rolling code system. Today’s security systems pretty much reduce the probability of accidently driving away with someone else’s vehicle to near zero, but typical automatic garage door openers not so much.


#6

Thank you all for your responses. Volvo_V70, your response was particularly enlightening.


#7

The vehicle owner can delete the Homelink transmitter signals. The procedure is in the owners manual, you do this before selling the vehicle.


#8

@Volvo_V70 Thank you.

Marnet
…still reading, still learning