Not Brelingo but Citroen

[RobS]

There are some clever chaps on here who may know why a key would stop triggering the immobilizer after changing the battery? 

OK it's not a Brelingo it's on my Citroen Relay van. I change the battery and the key fob case used the same PCB and key blade. it still opens the doors on the fob buttons and key blade. The engine cranks, the diesel lift pump runs but the engine will not start and the engine locked dash symbol stays on. I put my other key in and starts with no issues.  

It seems to have lost the link to this key. I have just recently acquired a Diagbox to link up with our Brelingo is there anything in the diagnostics system to reprogram in old keys at all?

[cancunia]

You might have left the immobiliser chip in the old key fob.

[Sol]

Spot on, the little black rectangular chip is usually placed or glued into a little slot near the start of the blade. Hopefully you didn't throw the old case in the bin.... DiagBox can reprogram keys but not those with no transponder chip.

[RobS]

That's a shabby Froggy trick. 

Just opened up the old case and down in a little slot is a very little black round thing. Not even sure how to get it out yet without doing any damage. Will take it apart if needed. 

When I did the Berlingo keys I only changed the PCB and blade the transducer must be on fixed on to the board.

[Sol]

Nope. The transponder is always a black plastic piece that is mounted near the point where the key blade starts, inside the casing. Needs no power, it gets powered from the ignition loop.

Nothing to do with French tech, all car keys have this.

If you damage the transponder, you're screwed. You will have to find a new one that is compliant with the system on the vehicle (new) and program it to the BSI with DiagBox. You will need the original security PIN code for the vehicle too.

[RobS]

Managed to get the little sucker out and into the new case and all is good with the world again.

On the front of the Berlingo PCB there is a much bigger oblong plastic box with a coil in it (that must energise the signal from a magnetic field in the ignition switch) . I assume that was it, the Relay one is separate to the PCB is a round cylinder very small and not able to see inside it.