Key not detected

[Jade92]

Really after some help. Yesterday my 2014 fiesta st3 wouldn't detect any of the 2 keys I have for it. After a while it finally did and I got it started. When I arrived home I changed both batteries in the fob but the problem still persists. It also will not lock from the outside. Can anyone point me in the right direction before I have to go to ford and empty my bank account? Thank you 

 

 

 

 

 

 

 

 

 

 

 

 

[unofix]

Start with the easy things first. Put the car battery on charge for at least 8 hours. Make sure you connect the negative lead of the charger to the chassis main earth point and NOT the battery terminal.

There are two functions of the keyfob and they are totally separate. (a) There is the passive transponder chip. It does not require a battery, and this is what the car's ignition reads to determine if the key is correct and allows the car to start. (b) There is the remote lock/unlock of the doors either by pressing the buttons on the keyfob or if keyless entry by it transmitting a signal so the car detects the fob and allows the doors to be opened. - This function does use the battery (Duracell CR2032) in the keyfob.

If the car is not detecting the keyfob's to allow it to be started then the problem is with the passive transponder chips. When the car battery state of charge falls too low it can cause problems with the keyfob being detected.

[Jade92]

Thank you I will start with the battery and see how I get on 

 

 

 

 

 

 

 

 

[iantt]

With a flat remote batteries or not,  the car should start instantaneously if remote fob is placed here. 

That's assuming the 12v car battery is ok. 

[autocat]

On 3/5/2022 at 4:05 PM, unofix said:

Start with the easy things first. Put the car battery on charge for at least 8 hours. Make sure you connect the negative lead of the charger to the chassis main earth point and NOT the battery terminal.

There are two functions of the keyfob and they are totally separate. (a) There is the passive transponder chip. It does not require a battery, and this is what the car's ignition reads to determine if the key is correct and allows the car to start. (b) There is the remote lock/unlock of the doors either by pressing the buttons on the keyfob or if keyless entry by it transmitting a signal so the car detects the fob and allows the doors to be opened. - This function does use the battery (Duracell CR2032) in the keyfob.

If the car is not detecting the keyfob's to allow it to be started then the problem is with the passive transponder chips. When the car battery state of charge falls too low it can cause problems with the keyfob being detected.

But what's the likelihood of BOTH key transponders having the same fault at the same time?

We have a similar problem with intermittent "key not detected" and "key fob battery low" warnings.

Have tried a BMS reset but that hasn't helped. So, a bit stuck for inspiration.

I'm beginning to suspect the problem lies within the vehicle not the key fobs after changing the fob batteries several times over a short period.

Anyone know where exactly the modules are located on a 2013 Ford Focus mk3 that process the signal(s) from the key fob?

ps I take your point about the vehicle main battery condition and will put it on charge to see if it makes any difference.

[unofix]

17 minutes ago, autocat said:

We have a similar problem with intermittent "key not detected" and "key fob battery low" warnings.

The passive part of the keyfob is the transponder. If the vehicle is not detecting the transponder the problem is with the vehicle not the keyfob.

17 minutes ago, autocat said:

But what's the likelihood of BOTH key transponders having the same fault at the same time?

Zero. As said above the transponders are passive. The problem is with the car.

It is extremely important that the car battery is fully charged. Using a multi-meter measure the voltage at the battery terminals after the car has been parked for 1 hour. A healthy fully charged battery should be 12.65V anything less than 12.50V and the battery is not in a fully charged condition.

Resetting  the Battery Monitor System (BMS) will not help the situation. You need to use a Smart Battery charger. Connect the positive charging lead directly to the battery terminal. Connect the negative charging lead to the chassis earth point, NOT the battery terminal. Leave the battery on charge for 12 hours.