P38A Alarm system flashes - battery empty

Frank_38 · 2025-07-28T07:55:53+0100

Good morning together,

unfortunately another problem. Apparently the alarm system has been flashing all night - just flashing - no sound.
When I tried to start the car - of course the battery is completely flat.

Now I have read that the RF receiver could be the problem. It is supposed to be in the right rear of the trunk and the solution is to disconnect the "blue cable" first.

Before I start my search, could this be the case?
I always open the door with the key anyway, so I don't use the remote control.

Yes, I'll be ordering nanocom soon.

Thanks!!!

DanClarke · 2025-07-28T08:25:08+0100

Well if it has been flashing all night then yes it is likely the alarm has been triggered. But if there was no sound at all it is also likely that the security settings are to sound the alarm sounder but maybe that has been disconnected?
It is generally along these lines:
Alarm System Configuration:

Alarm Enable/Disable: The primary setting to activate or deactivate the alarm system. Disabling it prevents the alarm from arming and stops all related audible and visual activity.
Alarm Lights: Adjust how the alarm visually indicates its triggered state (e.g., flashing hazard lights).
Alarm Noise: Configure the alarm sound settings based on market-specific requirements.
Arm/Disarm Notification: Customize the visual signals (e.g., flashing lights) when the alarm is armed or disarmed.
BECM Current Alarmed Status: Set the BECM to an alarmed or non-alarmed state.
Current EKA Lockout Status: Manage the BECM's response to Emergency Key Access (EKA) attempts.

Frank_38 · 2025-07-28T08:32:09+0100

ok, but these settings can only be configured with nanocom, right? or how can i deactivate the alarm system?

Should I disconnect the blue cable? thanks!

pwood999 · 2025-07-28T08:58:06+0100

Yes disconnect the RF antenna. It's the most likely cause.

Datatek · 2025-07-28T09:33:26+0100

Frank_38 said:
ok, but these settings can only be configured with nanocom, right? or how can i deactivate the alarm system?

Should I disconnect the blue cable? thanks!

A low battery can also cause the alarm to go crazy. As you use the key not the FOB, you can safely disconnect the blue aerial wire. If that doesn't help, disconnect the 3 pin connector to isolate the RF receiver completely, I have known an RF receiver to fail triggering problems. The receiver is under the flat plastic parcel shelf right hand side.

pwood999 · 2025-07-28T09:38:22+0100

@Frank_38 read this thread https://www.landyzone.co.uk/land-rover/p38-battery-drain.364514/#post-4994309

and go through the battery drain checks in BECM SID attached to post #32 in that thread. That will confirm if the problem is the RF receiver or something else.

P38A Alarm system flashes - battery empty

Frank_38

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DanClarke

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Frank_38

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pwood999

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Datatek

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pwood999

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