P38A Alarm Fault when inserting ignition key

Started getting the Alarm Fault message quite regularly. Based on various threads, I cleaned up the ultrasonic sensor connections, and also lubricated ignition barrel with graphite powder. Fault went away for two days, but now back again.

Need to double check all door latch switches tomorrow, but what else could be causing this ? Nanocom doesn't have option for Alarm or BECM fault codes.

pwood999 said:

Started getting the Alarm Fault message quite regularly. Based on various threads, I cleaned up the ultrasonic sensor connections, and also lubricated ignition barrel with graphite powder. Fault went away for two days, but now back again.

Need to double check all door latch switches tomorrow, but what else could be causing this ? Nanocom doesn't have option for Alarm or BECM codes.

Click to expand...

There are no BECM fault codes. I think the ultra sonic sensors are only active when super locked. What year is the car and is the BBus alarm fitted?

1998. BBUS is fitted but I’m sure I disconnected it years ago when it started chirping.

You sure there’s no alarm check on the nanocom I’m sure I’ve seen it somewhere

pete12345 said:

You sure there’s no alarm check on the nanocom I’m sure I’ve seen it somewhere

Click to expand...

You can turn the alarm off and you can choose between the horn and the siren

kermit_rr said:

You can turn the alarm off and you can choose between the horn and the siren

Click to expand...

I'd go for a horn everyday

pwood999 said:

1998. BBUS is fitted but I’m sure I disconnected it years ago when it started chirping.

Click to expand...

Is that an indication of the internal battery failing?

pwood999 said:

1998. BBUS is fitted but I’m sure I disconnected it years ago when it started chirping.

Click to expand...

In that case I suspect it might be the micro switch operated by the shutter in the ignition barrel sticking.

Barrel switch seems to be ok. Nanocom shows it toggle when inserting & removing the key.

All doors lock & unlock correctly with fob or key, but need to verify they actually change lock status correctly.

pwood999 said:

barrel switch seems to be ok. Nanocom shows it toggle when inserting & removing the key.

Click to expand...

Your proposal to do the door micro switch check would be my next step. Disconnecting the Bbus sounder does not flag a fault on mine

Checked all the BECM inputs with Nanocom earlier.

• All doors lock & unlock correctly using FOB, and flip from 12V to Ground in the Nano screens.
• Bonnet & Tailgate correctly show closed.

Strangely after connecting Nanocom & testing the stuff above, the alarm Fault message has gone away. Tried locking & unlocking both manually & with Fob, but fault no longer there. Bet it comes back later though

Shame the BECM menu in Nano doesn't have more details.

pwood999 said:

Checked all the BECM inputs with Nanocom earlier.

• All doors lock & unlock correctly using FOB, and flip from 12V to Ground in the Nano screens.
• Bonnet & Tailgate correctly show closed.

Strangely after connecting Nanocom & testing the stuff above, the alarm Fault message has gone away. Tried locking & unlocking both manually & with Fob, but fault no longer there. Bet it comes back later though

Shame the BECM menu in Nano doesn't have more details.

Click to expand...

Wet carpet and underlay in the drivers footwell?

Yes good idea. My plan is to take seat out & check the Kick Panel & BECM connections. Left footwell connections were soldered years ago, but never got around to doing right pair.