[RnR]

The key fob doesn't need power to transmit the radio waves?
Either to the door locks or BCM?

 

[phil]

The only thing the battery does on my key(no alarm) is lock and unlock the doors.

The part that gets the van to start doesn't need a battery, it just needs to be position next to the antenna ring that's around the ignition hole.

 

[RnR]

I thought he said "the BCM waits for a signal to be transmitted back from the transponder in the key fob".
So, the van sends a signal to the key and it just passively "reflects" back?
I'm not being a wiseguy. I'm seriously not understanding how this works.
Common sense says that you need power to send and receive signals. The OP put in new batteries and it worked. Made sense in my head.
But I don't know anything about RF tech.

 

[phil]

Should work similar to the id cards that employees wave over sensors that allow them to access locked rooms.

My van doesn't have electrical problems and starts fine. I would remove the fob battery and test it, but I don't want to push my luck

 

[RnR]

I still can't say I know exactly how that tech works (s'pose I could Google it), but that was a good example. I actually use a swipe badge at work every day.

 

[RnR]

I googled it.
There was zero reason for me to know how that works and stuff just a little more useless info into my head.
But I have issues and I did.

 

[uralwrench]

My fob batteries have worn out a few times over the years. Locks become glitchy and range for it drops greatly. And range is only ok to begin with. Cheap batteries have only lasted a couple months. (Tractor Supply big sheet of cheap disk batterys) Name brand ones from the drug store last a year or so. Never had issues starting the van though.

 

[travelvanvan]

My fob batteries have worn out a few times over the years. Locks become glitchy and range for it drops greatly. And range is only ok to begin with. Cheap batteries have only lasted a couple months. (Tractor Supply big sheet of cheap disk batterys) Name brand ones from the drug store last a year or so. Never had issues starting the van though.

Yes, I've steered away from cheap coin batteries. I bought some cheap ones from Amazon thinking "this is such a simple technology [ chemicals in a coin-shaped container ], they can't get it wrong". Well, they didn't get it "wrong" per se, but the manufacturer likely used less chemical to save money. They consistently lasted at most a year.

Recently I bought a sleeve of Duracells from Costco. A name brand (though I normally hate Duracells) from Costco. We'll see how well they perform. All I know is the OEM batteries that came with new fobs--not just of the PM but from a variety of other vehicles and brands--have all lasted multiple years, as many as 5 or 6.