Dave1127i

Hi I have a fault with the Alarm on my 2.5 v6 estate, the alarm goes off intermittently when the alarm is set, it could be 3mins or 7 hours when it goes off, I had the ecu faults read at my local garage and the only alarm fault came up as, fault lost 23.

Can you shed some light on this, as I am having to disconnect the battery when not in use.

cheers

georgeb944

You (or your mechanic) needs a better code reader. Most of us here recommend the full version of VCDS, or the VAG scan tool, which has access to all the modules, not just the ECU.

That said, it is most likely a fault of the Alarm control module, or one of its inputs.

Dave1127i

I have had the ecu read again today, the code is 01373, Alarm triggered by radio ground contact.

georgeb944

Bad or non stock radio. The alarm system is thinking that someone is trying to remove your radio.

There may be a way to fool the alarm into not checking for that situation.

Dave1127i

yeah it's a non stock radio, only just bought the car, it had an old non standard radio in it, so i changed it, and now the alarm is thinking it has an earth fault, so what are you thinking George.

georgeb944

Get a wiring diagram for your car. There should be a wire from the radio to the alarm control unit. Use some shrink wrap to isolate that wire and the alarm should stop going off. Of course, it will also not go off if someone tries to steal your radio...

Dave1127i

thank you George, i will check that out.

Dave1127i

Can anyone see the radio anti theft wire, cos i can't, help lol

georgeb944

I found a wiring diagram for the connection between the radio and the alarm control module. The wiring diagram is for the Central Locking/Alarm/Ultrasound Interior Monitor module.

SloopJohnB@mac.com

from radio to alarm control unit. I suspect that wire needs to be grounded to indicate the radio is connected. Isolating that wire would be the same as removing the radio EXCEPT for the diagnostic that radio ground contact.

First find the wire from the OEM radio connector. How did you install the non-OEM head unit? If you used a Crutchfield adaptor check back with them and see if they've had this problem or even re-read the Crutchfield instructions!

If you've spliced into and left hanging the OEM connector(s), then you'll have to experiment like one guy has said...safest way is to literally isolate the brown/grey wire (tape it so it can't ground) and see if it shuts off the alarm. It should, if the diagnostic is correct.

Although 'alarm triggered by radio ground contact' seems clear, reading german wiring diagrams and fault codes can be confusing and vague..a ground fault can be an actual ground or failure to ground. If the wire from the central locking unit to the radio doesn't have 12v power to it with the car running, it should be safe to ground it if taping it off doesn't shut off the alarm.

PS: You might have to erase the DTC code IIRC.