Key fob flashing - odd behaviour and no sync possible

[zzsteve]

My remote locking has lost sync for no apparent reason and when I try to re-sync, I notice that the LED on the key fob flashes about twice per second initially and then flashes slower (i.e. every second). It used to flash faster when the buttons were held and this when the sync occurred when you had the key in door with the lock and unlock positions held for 3 seconds.
Car starts with the key OK.
Is it a key fob fault or does 'something' need to be reset?
TIA

Steve
'97 HSE

[PeterH]

The first thing that comes to mind, is it possible the fob battery is low, or the contacts inside the fob need cleaning?
That's the first thing I would check.
Sometimes I find the remote will not operate the locks in some locations, like my local supermarket car park.
For what ever reason I have to manually lock the car with the key there.
It might be some sort of RF or electrical interference, so maybe try the remote with the vehicle in a different location and see if that works.
Failing that I wonder if the contacts on the fob buttons need cleaning? Could be as simple as that.
Hope that helps!
Cheers, Pete.

[4X4V8]

My remote locking has lost sync for no apparent reason and when I try to re-sync, I notice that the LED on the key fob flashes about twice per second initially and then flashes slower (i.e. every second). It used to flash faster when the buttons were held and this when the sync occurred when you had the key in door with the lock and unlock positions held for 3 seconds.
Car starts with the key OK.
Is it a key fob fault or does 'something' need to be reset?
TIA

Steve
'97 HSE

As Peter said, I'd be checking or replacing fob batteries and checking connections in the fob. The contact on the round battery cover on mine was bent I think. Can't exactly remember, it was ayear ago, but I had problems similar to yours and fresh batteries and adjusting the contact on the fob fixed it.

[peter51]

By using a frequency analyser we discovered that a flashing red LED doesnt mean that the FOB is transmitting any RF - the SAW resonator can be dead and no 433Mhz burst is transmitted- yet the LED will flash.
Firstly check for dry solder joints where the battery holder is attached to the board.
If OK take it to an electronics workshop to see if it is emitting a 433Mhz burst.
If not they can order a new SAW resonator and resolder it for you- dont try yourself.

[zzsteve]

By using a frequency analyser we discovered that a flashing red LED doesnt mean that the FOB is transmitting any RF - the SAW resonator can be dead and no 433Mhz burst is transmitted- yet the LED will flash.
Firstly check for dry solder joints where the battery holder is attached to the board.
If OK take it to an electronics workshop to see if it is emitting a 433Mhz burst.
If not they can order a new SAW resonator and resolder it for you- dont try yourself.
Thanks Peter,
I can detect the rf with my scanner (may have been 315 MHz actually -I'll check again)
Is there any chance the induction pick-up from the key barrel is not working and somehow affecting the function of the key fob micro ?
Cheers,
Steve

[peter51]

Have you access to a nanocom - to disbale passive immobilisation and set Alarm disarm: This setting programs the effect that usage of the vehicles key has ondisarming the alarm system. Options:
 Operation of the key in the drivers door can always disarms the vehicle (ALWAYS).
https://www.nanocom-diagnostics.com/uploads/downloads/Discovery%20II%20Valeo%20BCU%20ECU%20Guide.pdf
While you are there completely disable superlock.
Read through the above link to see other security options available.

[zzsteve]

Have you access to a nanocom - to disbale passive immobilisation and set Alarm disarm: This setting programs the effect that usage of the vehicles key has ondisarming the alarm system. Options:
 Operation of the key in the drivers door can always disarms the vehicle (ALWAYS).
https://www.nanocom-diagnostics.com/uploads/downloads/Discovery%20II%20Valeo%20BCU%20ECU%20Guide.pdf
While you are there completely disable superlock.
Read through the above link to see other security options available.

OK, Good tip. Will attack it with Nanocom and advise.
steve

[zzsteve]

OK, Good tip. Will attack it with Nanocom and advise.
steve

Dug out the Nanocom Evo, but the guide in the link is for D2 Peter.
https://www.nanocom-diagnostics.com/downloads/preview/p38-becm is my setup.
Regardless, I can't see anything here to help.
My settings are:
Immobiliser - DISARM
Lazy Locking - DMH key only
1 touch- NONE
Arm/Disarm - DISARM
Alarm - ENABLED
Mislock -SOUNDER
Al. noise - PULSED
Sounder - KLAXON
Al. Light - HAZARDS
Key warning - DISABLED
EKA - DISABLED
(no EKA or fob codes visible)

Minor panic as reading/writing these puts the BECM and message centre into DIAGNOSTIC MODE with no way to get out of it. No engine start - nothing. Battery disconnect and reboot was the only cure.
EDIT: This is due to not exiting the menus on the Nanocom properly - sorted now.

Reading RF memory shows it is seeing the rf signal from the key fob at least

Essential problem seems to be a change in the state of the key fob so it doesn't go into that rapid LED flashing resync. mode anymore. Neither of my keys do, which led me to think it was some abberrant reset due to the BECM somehow.

Still stumped.
TIA
Steve