Keyless Avensis "no key detected" after car battery change

[Hymerist]

Hi all, hoping someone can help. We have a T Spirit 2011 T27 Tourer and the vehicle Battery failed completely whilst away on holiday for a week.  I replaced it this morning and initially the car remained dead but following the dash messages, I held the fob against the engine start button (no ignition keyhole) and depressed the clutch and the engine started apparently all good. However, when the engine was turned off, the dash reported no key detected and to start the engine I again had to depress the clutch and hold the key against the start button which responded with a "beep" and again the engine started. Both fob batteries have been recently replaced and the small red LED flashes with any of the three buttons being pressed. However, neither remote will now lock or unlock the car and the previous mentioned routine is required each time to start it.  It appears that the car has "forgotten" the remotes with the new engine Battery replacement so is there some sort of routine (opening doors and windows?) of which I'm unaware. Both fobs worked perfectly before the vehicle Battery replacement. All online searches keep referring to ignition key routines or dead fob batteries and that's not what the issue is, TIA as I have run out of ideas.

[PCM]

Do you have to hold the fob next to the starter button...?

Or something similar?

[Hymerist]

I do.  Touching either fob to the start button elicits a beep and a message to depress clutch as normal and press start.  Engine starts but "no key detected" is subsequently displayed.

[TonyHSD]

Where do you keep the key fob when message pops up? 
These key fobs are very sensitive to electronics. If you place it next or over magnets, other devices, phones, credit cards etc it may trigger this warning. 
The other reason can be if the new Battery it’s not fresh. It could be old stock and some of these are known to cause trouble. 
The best place to keep key fob is in pocket away from anything else, just the key and nothing else. No remote controls for garage doors, no cards, no magnet phone cases.  

[Hymerist]

Thanks for that but both fobs worked fine before the vehicle Battery died and was replaced.  Once the new Battery was fitted neither fob worked.

[PCM]

Is it called, 'reseeding'?

[m456an]

You answered the question, once the new Battery was installed. Was it same type of Battery? The voltage may be good, but have done a load test on it....Have you tested Avensis with a different Battery. Just for test purposes you can try a battery from another car. If so you may be able to return your new battery if you have a paper or digital receipt.

[2009joe]

well i checked a Panasonic Battery with my volt meter and was over 3v with my key fob and would not work then i took the Battery out of my working key fob and it started working again. so tbh was the Battery fault 

[TonyHSD]

Sometimes the car may stop recognise the keys. If this happens you have to open the car with your emergencies key blade, get in as most likely the alarm will be set off . Start the car while keeping the fob next to the start button. Let it run for a while 15-20 min to recharge then12v Battery in case this was the reason for the problem. Then to reprogram your keys you need to turn ON the car and turn off , this is double push start button without pressing on the brake, then open and close the drivers door twice within 40 seconds. The key will be recognised by the car. The other key might be too, if not repeat the procedure. 

[Hymerist]

On 8/21/2023 at 8:46 PM, TonyHSD said:

Sometimes the car may stop recognise the keys. If this happens you have to open the car with your emergencies key blade, get in as most likely the alarm will be set off . Start the car while keeping the fob next to the start button. Let it run for a while 15-20 min to recharge then12v battery in case this was the reason for the problem. Then to reprogram your keys you need to turn ON the car and turn off , this is double push start button without pressing on the brake, then open and close the drivers door twice within 40 seconds. The key will be recognised by the car. The other key might be too, if not repeat the procedure. 

Thanks for the reply TonyHSD,  Tried that process but no joy.  I have to touch the fob against the start button for the button to work (button LED goes red), then two presses on the button switches on the dash (ign. mode) and a third press switches off.  Repeat and then open/close door twice?  Unlike a key in the ign lock, this process is pretty slow am I doing it wrong?  Any other thoughts?

    

[Hymerist]

On 8/21/2023 at 4:09 AM, m456an said:

You answered the question, once the new battery was installed. Was it same type of battery? The voltage may be good, but have done a load test on it....Have you tested Avensis with a different battery. Just for test purposes you can try a battery from another car. If so you may be able to return your new battery if you have a paper or digital receipt.

I did, in fact I desulphated the original Battery, top charged it and refitted it.  Didn't help sadly.  What is puzzling is that there are moments when the system actually works, irrespective of number of journeys or journey times, after a few hours it returns to no remote arm/disarm and "o key detected" in cabin.

[TonyHSD]

3 hours ago, Hymerist said:

Thanks for the reply TonyHSD,  Tried that process but no joy.  I have to touch the fob against the start button for the button to work (button LED goes red), then two presses on the button switches on the dash (ign. mode) and a third press switches off.  Repeat and then open/close door twice?  Unlike a key in the ign lock, this process is pretty slow am I doing it wrong?  Any other thoughts?

    

Hi, 

should have worked  if you have followed the steps in order, but if it didn’t it might be something else.. perhaps try again from beginning. 
I had some issues last week with my car, for some unknown reason both remote keys were unrecognised, their batteries were recently changed 3 months ago. 
I run that procedure, I fought it here in previous posts and then after all went back to normal. Same unlock with emergency key, start the car with touching the start button with the fob and then after turning off the car and do the reprogramming of the key fob. I don’t know another way. Period someone else can help. 
Good luck