Keyless entry suddenly stopped working

Hi all, I have a specific question about the sudden failure of the keyless entry function.

Yesterday, when I tried to start the car with the starter button (unlock function worked perfectly at this point), the Prius dashboard displayed the key symbol, indicating that it did not recognise that the key was in the car, so I wondered if the battery was losing power even though it was only a few months old (replaced earlier this year) .

I had another Fob which needed a battery replacement, so I thought I'd have Fob 1 battery checked and also have a new battery put into Fob 2. Everything was working fine prior to having the battery checked at the battery replacement store.

The problem is now that neither of my smart keys will operate the smart entry. Both keys will start the car from inside when I press the starter button, but neither key now operates the lock/unlock function.

I also tried using the lock/unlock function whilst sitting in the car and I noticed that I needed to press the Fob button a couple of times before it worked (on both Fobs), so I wonder if the chap who checked and replaced the batteries has perhaps caused the buttons to stick?

I switched the smart key function cancel button off and on a couple of times, but this hasn't made any difference.

I did wonder whether this situation might also be an indication that the 12Volt battery in the boot might be starting to fail and it seems that this is a possibility after reading previous posts. However, I don't want to go to the expense of purchasing another 12 volt battery if this is not the problem, hence my query here first.

As it stands right now, I can't lock/unlock my car with the remote, and will have to use the manual key - very inconvenient.

I hope there is a simple, affordable fix for this. I really do not want to have to take the car to have the keys re-programmed. I've found an article about how to program the keys myself, but I'm hesitant about taking this step as I could really mess things up.

Thanks in advance.

 

Hi and thanks for responding so quickly.

I only purchased one battery, but I did have the chap check the other battery to see if it still had a good charge. He didn't replace that battery. The car is able to start with both Fobs, so it if was faulty batteries, wouldn't that affect the starter motor too, as well as the unlocking/locking function? Both Fobs work except for the locking/unlocking function. It just seems very odd that Fob 1 suddenly stopped working after the battery cover had been taken off and checked.

I've just checked the receipt for the 12V battery and it was replaced in May 2014. I suppose it could be nearing the end of its life?

 

Thanks for the suggestion about disconnecting the 12V battery. Please excuse my ignorance, but how do I do that? Just unplug the leads?

 

Thanks again. I did a Google search to see how to replace the 12V battery - think I'll leave that one to the experts. In the process I came across a couple of videos that showed how to check the Auxiliary battery on the diagnostic screen.

In 'Maintenance' I checked the Battery, and as suggested on the YT videos, I switched the lights on 3 times to get the diagnosis. My screen looked different to the YT videos (I'm in Australia and they are US videos) but after flashing the lights, the message came up to change the battery, so I suppose that's the problem. It is 4 years old.

Also, when I started the car today the key symbol came up again, which I think means the car isn't recognising that the key is there. So, if the 12V battery needs replacing, would this cause the issue with the key (i.e. car not registering that the key is in the car and the lock/unlock function)?

Thanks for your help thus far.

 

Okay thanks for that advice. I will have the 12V battery tested just to make sure.

And I'll take one key Fob to another battery place and get a new battery as suggested by you. Thnx for taking the time. Cheers

PS: It might be a couple of days before I resolve this (weekend coming up) but I'll let you know how it gets sorted.

Again, thanks. Cheers

 

Hi JC91106 - just thought I'd let you know current situation. The situation seems to have rectified itself and I have no idea how.
Yesterday I'd decided to get battery for Fob 1 changed again, as you suggested.

When I left home, I had to insert the key as the car was still not recognising the smart key, but as I was getting out of the car, I automatically pressed the lock button (out of habit) and it worked. After that, it has worked every time (so far).

In my search for a solution, I read about how the Fob signal still communicates with the car if they are within 15 feet of each other, which mine is. So I've decided to turn off the smart key function at the end of each day and see if that lengthens the life of the Fob batteries. I haven't driven the car today so I'm hoping that all is well.

I'll let you know if there's any further issues, but thought you may be interested to know that it seems to have righted itself (hopefully). I'm keeping Fob 2 upstairs and a long way from Fob 1.

Thanks for taking the time to offer solutions. I am hoping that this is the end of it (until the battery really needs changing).

Cheers