Merc Vito electrical issue

[CarolineD1085]

Hi,

I have a 2006 Merc Vito 115Cdi van. A while a go the alarm started to.play up, factory fitted. It would go off randomly in the night, during th day and even whilst I was driving. Once going off I could not stop it. At the same time the interior lights stopped working. What I have now found is that if the alarm doesn't play up, and it can go weeks without an incident the lights work. When the alarm is playing up the lights won't come on at all. Now the remote central locking is also playing up. Sometime it won't unlock for ages. Something is obviously getting confused somewhere. I've taken it to a few garages and no luck. Merc said they would have it in and estimated over £500 just to diagnose the fault before they do any work. Does anyone have any suggestions as to what it maybe?

Thank you!!

 

[M80]

A Merc independant would diagnose cheaper, the problem is that trying to find a fualt when it's not there can be difficult.
If your lucky there will be stored codes that 'might' point to the remedy.

Alarm wise I can't comment but interior lights faults 'can' be the SAM,
1st I would check your under bonnet fuse box to see if water has got into it.