Xantia keypad immobiliser

[RaphaelPF]

Hello guys.

I have a 1995 Citroën xantia with problems in keypad.
The red light is pulsing but when I turn on the ignition the red light turns off and I can't put the code.

The car doesn't star and the keypad doesn't make any beep. Only when I turn off the ignition the red light return to pulse.

Any ideas how to solve that issues.

Thanks

[xantia_v6]

Which engine?

[RaphaelPF]

Its a petrol 2.0 8v

[CitroJim]

Do you ever see the red and green lights on at the same time?

[RaphaelPF]

No, the car was parked for a while and the baterry was dead, I charged it and when I tried to start the engine the red light turns off.

I've never had the both lights on.

[xantia_v6]

Try disconnecting the battery for a minute then reconnect it.

[wheeler]

Its a strange one as normally with keypad issues you either get both lights or no lights at all.
Is the engine still turning over if you try to start it?
If battery disconnect fails check all the fuses.
The fact the red light goes off with ignition on could possibly mean there is no ignition live feed to the keypad anymore?

[xantia_v6]

To clarify my suggestion re the battery disconnect, I have had petrol Xantias where the ECU gets into a locked up state if the battery voltage drops very low, but not to 0, then is charged or boosted without being disconnected to give a clean ECU reset.

[CitroJim]

I've had one instance where I've resolved a keypad issue on a petrol Xantia using an ELIT (not Lexia) diagnostic device using the 'Coded Anti-Theft' menu. If all else fails, this might be worth a try although it may be challenging to find an ELIT these days, especially in Brazil.

A Lexia, in my experience, will not do what's needed.

[RaphaelPF]

To clarify my suggestion re the battery disconnect, I have had petrol Xantias where the ECU gets into a locked up state if the battery voltage drops very low, but not to 0, then is charged or boosted without being disconnected to give a clean ECU reset.

Hello, sorry for the delay to reply.

I disconected the battery for 10 minutes and tried again, but unsuccessfully. I leave the car with the battery plugged in. What you are saying to me is to try to leave the battery with near 0V and plug a charger in it while is in the car?

[RaphaelPF]

I've had one instance where I've resolved a keypad issue on a petrol Xantia using an ELIT (not Lexia) diagnostic device using the 'Coded Anti-Theft' menu. If all else fails, this might be worth a try although it may be challenging to find an ELIT these days, especially in Brazil.

A Lexia, in my experience, will not do what's needed.

Yes, I tried to find this diagnostic device and I have no luck. The only scanner I've found was this one:
https://pt.aliexpress.com/item/10050051 ... Redirect=y
and it's still need a adapter because the xantia mk1 is 30 pins.

Do you think this one can help me?

[xantia_v6]

To clarify my suggestion re the battery disconnect, I have had petrol Xantias where the ECU gets into a locked up state if the battery voltage drops very low, but not to 0, then is charged or boosted without being disconnected to give a clean ECU reset.

Hello, sorry for the delay to reply.

I disconected the battery for 10 minutes and tried again, but unsuccessfully. I leave the car with the battery plugged in. What you are saying to me is to try to leave the battery with near 0V and plug a charger in it while is in the car?

No, the opposite...
It is the gradual raising of the voltage which can cause the ECU to lock up.

[RaphaelPF]

To clarify my suggestion re the battery disconnect, I have had petrol Xantias where the ECU gets into a locked up state if the battery voltage drops very low, but not to 0, then is charged or boosted without being disconnected to give a clean ECU reset.

Hello, sorry for the delay to reply.

I disconected the battery for 10 minutes and tried again, but unsuccessfully. I leave the car with the battery plugged in. What you are saying to me is to try to leave the battery with near 0V and plug a charger in it while is in the car?

No, the opposite...
It is the gradual raising of the voltage which can cause the ECU to lock up.

Sorry, but I really couldn't figure out how I could rise the voltage gradually.
Because I can low the voltage using the battery, but to rise I need to charge it with a regular car battery charger so how can I do that?

[xantia_v6]

A battery charger will raise the voltage gradually because it cannot supply enough current to charge the battery instantaneously.

[CitroJim]

Do you think this one can help me?

That's a Lexia Clone and very unlikely to be useful to you, even with an adaptor lead...

Also, it is suspiciously cheap. Too cheap...