Fobbed off

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

User avatar
Sloppysod
Donor 2021
Posts: 698
Joined: 23 May 2015, 23:35
x 113

Fobbed off

Post by Sloppysod »

My spare Key fob has stopped working, it's not the battery, how do I replace, is it something I can by 2nd hand and recode, if so how do I recode without main dealer expense?
When I unlock the car, with the key, the alarm sounds until the key is in the ignition so the transponder is fine. #-o
User avatar
GiveMeABreak
Forum Admin Team
Posts: 29016
Joined: 15 Sep 2015, 19:38
x 3610

Re: Fobbed off

Post by GiveMeABreak »

Try re-synchronising it Stu.

Put the spare key in the ignition, turn to ignition, within 10 seconds, press the lock button for a few seconds only, release, then turn off the ignition and remove the key (important). Wait 15 seconds, then exit vehicle and attempt to lock / unlock with the fob. Sometimes the remote can become unsynchronised if using at distances frequently where the rolling code exceeds it's limit. Resynching the fob will reset it.
User avatar
Sloppysod
Donor 2021
Posts: 698
Joined: 23 May 2015, 23:35
x 113

Re: Fobbed off

Post by Sloppysod »

Cheers Marc, worked once, then tried the fob after a few minuets and it packed up again!!
So replaced the battery again, followed the steps in your post and did not work!!......so tried agin but waited 15 secounds AFTER the interior lights turned off and viola!, it worked thanks.
So does that mean it would be wise every so often to try the spare fob!!
User avatar
GiveMeABreak
Forum Admin Team
Posts: 29016
Joined: 15 Sep 2015, 19:38
x 3610

Re: Fobbed off

Post by GiveMeABreak »

Actually that was my bad Stu - It is actually recommended to wait 30 seconds after resynchronising and removing the key before pressing the buttons. So your 15 was lucky.

The rolling code of the remote control is modified each time the remote control is used. A small offset between the rolling code expected by the receiver - and that transmitted by the remote control is tolerated (in case of using the remote control outside the range of the receiver).

In the event of this tolerance being exceeded it is necessary to resynchronise the remote control. The tolerance is of 255 offsets. I alternate use between mine to be honest.
User avatar
Sloppysod
Donor 2021
Posts: 698
Joined: 23 May 2015, 23:35
x 113

Re: Fobbed off

Post by Sloppysod »

GiveMeABreak wrote:
09 Jun 2019, 15:44
..............I alternate use between mine to be honest.

Going to do the same here now as well......
belaprops
(Donor 2020)
Posts: 94
Joined: 05 Dec 2019, 23:20

Re: Fobbed off

Post by belaprops »

Hi guys,

Was excited to see a solution, but it does not work with mine C5 2011,
The battery I checked but nothing seems to sync the key

How can I test if the key actually is alive

I can not alarm my car now which is a bit alarming

Cheers
Bela
User avatar
GiveMeABreak
Forum Admin Team
Posts: 29016
Joined: 15 Sep 2015, 19:38
x 3610

Re: Fobbed off

Post by GiveMeABreak »

@ Bela

So what actually is your problem specifically?
Without specifics, I'm assuming your fob is not locking or unlocking the car or any of the remote functions? What does your middle button do? Do you have the powered tailgate or guide me home lamp option for the middle function? Have you tried whatever option it is and does that work or not?

Other possibilities: The battery in the fob is dead or weak (or if replaced is the wrong type) - be careful some of those coin batteries look the same but they are not. You need a CR0523 3Volt.

Next, check your shunt fuse in the passenger compartment glovebox is not in the SHUNT position.
belaprops
(Donor 2020)
Posts: 94
Joined: 05 Dec 2019, 23:20

Re: Fobbed off

Post by belaprops »

Hiya Marc,

Thanks for the info, I believe it's a guide me home middle button, no powered tailgate
Its a 2011 model.

The bat is ok, replacement cr1620, it measures more the 3v and it does not drop on pressing one of the buttons. Plus is up as engraved in the holder

The shunt fuse is new to me in this story, it's currently in the right side of the 3 way fuse socket.it has Parking/client marked above

Any suggestions are very welcome
belaprops
(Donor 2020)
Posts: 94
Joined: 05 Dec 2019, 23:20

Re: Fobbed off

Post by belaprops »

The shunt is in client, so not in parked up, I understand the use of it, I presume that is what you ment
belaprops
(Donor 2020)
Posts: 94
Joined: 05 Dec 2019, 23:20

Re: Fobbed off

Post by belaprops »

Success!! After trying everything it seems to have been a circuit board issue.
Determant to check everything I found under a
2 lines damaged on the PCB. I repaired the damaged lines which disappeared under the centre switch, but also 're soldered the 3 points of the battery clip. Initialized the fob and result.
I now don't know if it was the lines or the power I soldered but it works,
Not sure what the middle button does as the close button also makes the indicators flash after activating the alarm..
Thanks for the help, now back to more engine problems
User avatar
GiveMeABreak
Forum Admin Team
Posts: 29016
Joined: 15 Sep 2015, 19:38
x 3610

Re: Fobbed off

Post by GiveMeABreak »

Ok, so the CR1620 battery in the fob is OK as a replacement.

Yes, the Park shunt fuse should be shunted to the right, which seems to be ok too.

So next check fuse F10 in the passenger Glove box

Failing that I would examine the fobs themselves, specifically the circuit boards and make sure you haven't got any broken microswitches. If you have have the spare fob, try that as I doubt both would of gone at the same time - and if they both don't work after resynchronising, then it will need further investigation.
User avatar
GiveMeABreak
Forum Admin Team
Posts: 29016
Joined: 15 Sep 2015, 19:38
x 3610

Re: Fobbed off

Post by GiveMeABreak »

belaprops wrote:
18 May 2020, 15:52
Success!! After trying everything it seems to have been a circuit board issue.
Determant to check everything I found under a
2 lines damaged on the PCB. I repaired the damaged lines which disappeared under the centre switch, but also 're soldered the 3 points of the battery clip. Initialized the fob and result.
I now don't know if it was the lines or the power I soldered but it works,
Not sure what the middle button does as the close button also makes the indicators flash after activating the alarm..
Thanks for the help, now back to more engine problems
I posted my response just after you submitted your fix :-D

On your car you have central deadlocking - so first press of the lock button will lock the car and the second press will deadlock the car (i.e. the doors cannot be opened from the inside of the car).

Anyway it's sorted now - it can happen over time as we all tend to drop our key fobs - and this can weaken the components on the board.
belaprops
(Donor 2020)
Posts: 94
Joined: 05 Dec 2019, 23:20

Re: Fobbed off

Post by belaprops »

Thanks for the help again, hopefully I will have a great working car after lockdown, all the 3 fob functions work fine now.