Keyless starting difficulties...
 

Hey guys my wife is having some trouble occasionally with the keyless start on our 07 4.8i and besides making me nervous and changing the key fob batteries the other day, I'm uncertain what makes the keyless starting act up. With the key inserted, all goes well, according to the driver. The one time I had to come rescue her, the car started keylessly without a hitch, and I drove home without incident. She knows the procedure for starting keylessly. She earns 250$k a year and is smart as hell........I wonder if it's the original battery starting to wane?

Anyone have keyless go wonkiness?

Not sure about your problem but can she adopt me?

I call her, Sir.

What does her earnings have anything to do with her not being able to start the vehicle with the key not in the slot?

Anyways....maybe it's her not pushing the brake pedal in all the way? And just by chance when the key is in the slot, she pushed the brake in just enough for it to start?

Sometimes I have to push harder on the brake than others for my truck to start. Otherwise it just cycles the power to the nav/lights/etc and I sit there wondering why it wont turn over.

LOL I thought the same thing and agree on the hard brake prior to starting.

My point is she's no dumb housewife stuck at the supermarket. I was anticipating some comments to that effect. The lady is super capable all around.

I agree with you both on the brake pedal/ pressure as the culprit.

If anyone has experienced actual signal from the fob problems, etc let me know, please.

I work in computers - and the most infuriating problem description I ever get is "it doesn't work".

WHY?! What error / problem / issue is the user experiencing?

If it's blasting a "key not present" error, that's no biggie. Worst case, she can put the key in the ignition - but my guess is that it's next to a cellphone or a metal case that's blocking the RFID signal back to the car.

I'm in software development, so I hear ya.....she probably has an iPhone and/or metal very nearby in that big purse of hers. Would a bunch of keys attached to the fob screw with the RFID?

IDK about that...I have my keys next to my cell, iPod's, in the center console, in the back seat in my bag next to my laptop (ThinkPad; made of magnesium alloy), etc etc. Never had an RFID problem. Ever. Maybe if you had a Griffin iPod transmitter from 2004 giving off static next to your cell, sure. But not the key fob.

Regardless, tell your wife to step harder on the brake from now on and see if it still happens. If it does, perhaps you have battery issues, electrical issues, comfort access issues, key fob issues, wife issues, the list goes on. I doubt it's that severe. I'd imagine it's just her not understanding that the truck needs ample pressure on the pedal.

Car has been fine since I've been driving it.......

My M has comfort access and the battery in the key does wear out. Just replace it and see if that resolves it. I notice that when the battery was getting low I had to get closer to the car to get it to unlock the doors and sometimes pressing the start stop button a few times. I replaced the battery and problem resolved. It takes about 3 minutes and a $6 battery. Good luck

No program is required after battery replacement?

Nope. I replaced both fob batteries and no adverse reactions.....

Sounds good. One of my fob's seems to be low on juice. I'll grab a couple new batteries today. Thanks.

Correct. Plug and play

I have noticed with comfort access on my 2011 that I can make the keyless start not work. Did it by accident.

If I have my keys in my pocket with my iPhone and the iPhone is blocking they keys, the car won't start. Makes perfect sense, so now my keys are in the opposite pocket.

Never had that issue with an iPhone, BB, Droid...nada. Maybe it's your leg? You happen to venture over to Japan recently? Specifically near the nuke plants? :wow:

Ordered 5 of them on amazon for $7ish shipped. Thanks again!

Well it was in my left pocket and the signal had to go through "stuff". ;)

My question is...where and how many sensors are in our trucks for CA?

It's weird...when I leave a fob in the center console and take one with me, I can lock the doors. The driver's side isn't supposed to lock if it detects a key is inside the vehicle. The keyfob inside's battery is fine so it's not like it's just a dead battery and the truck doesn't detect it.

Do we have a few sensors inside the truck in order to triangulate the position of the keyfobs? Or is it just one that uses some sort of radio measuring to detect and pinpoint where the keyfob(s) are?

Had the similar issues with mine (2008) - always had to make sure the iphone was in the opposite pocket or else i couldn't get in the car, let alone start it. My buddy has a 535 w/CA and has no issues. CA always seemed to be weak in mine (even with new batteries in fob) and there were times that i'd have to use the remote to get in as it wouldn't open.

There are nine antennas.

Four exterior, one in each exterior door handle.
Five interior; one in each front footwell, left and right, two in the trunk (left and right), and one in the trunk centre.

Each covers 2 meters. These antennas also have transmitters built in.

I would change your second paragraph. The vehicle isn't supposed to lock when the key is left inside the vehicle. When you leave a key in the vehicle, I don't believe you are locking the vehicle with the key left there. You are locking it with the one in your pocket. Each transmitter is sending encrypted messages.

Also, the fob transmitters have two stages of low battery, first the warning, then the shutdown (and data retention).

The vehicle receivers also have multiple modes, governed by the sleep status of the vehicle. The sensors in the door handles are duplicated, with both capacitive sensors and Hall sensors. As the vehicle goes to sleep, the capacitive sensors are switched off. The remote transmitter fob doesn't always transmit. It just waits. When you touch the door handle, a wake-up request is sent. Then a message is broadcast from the door handle to ask which transmitter is out there. The transmitter sends back an encrypted message identifying itself. The vehicle then acts on that. All this is by way of saying that it is far from a simple "open" command from the fob, it is a wake-up routine involving a dedicated bus in the vehicle, and this bus is designed to be asleep to save the vehicle battery. Or try to.

And people wonder why these vehicles get flat batteries.

Related to the last post above, if the fob button works but the Comfort Access is weaker, I wouldn't look to the fob, but rather the circuitry on the vehicle that wakes up the Comfort Access, and which transmits a request to the fob. If the fob can send an open signal from the unlock button, it can probably send a coded response (same battery). It just has to be asked for that response, and perhaps hasn't been asked yet.

There are documents posted here with the full Comfort Access schematics and technician training notes. Interesting stuff.

Good job JCL!

Well, after a flawless first week and long roadtrip, some bad news, on Sun the car AC suddenly got warm, & started to overheat, so I immediately shut it down. Aux fan inactive. Towed to my Indy. 2d time for the fan relay, and first time the fan was replaced. Then the battery starts draining. New battery installed. Seems my e70 won't go to sleep now. I have a MOST (or is it CAN?) BUS module that is an insomniac likely......Never did THAT before! Also had the washer fluid hose routing update done. Looks like the vehicle will need some reprogramming/recoding tomorrow to get everything back in line. These items were "fixed" prior to my purchase of the vehicle at my request as part of the deal. Er, perhaps not. The bill is going to the dealer on this one!