Mercedes ML350 (W163) Dangerous Problem

[MilleMigliaDave]

Hi, my '04 ML350 has just started 'shutting down' whilst driving. The electrics all go off, the engine stops and the dash lights all go out. It's almost as if the battery has been disconnected - the one thing that tells me that this is not the issue is that when trying to re-start, the Airbag lamp lights - but nothing else - no hazards, no radio, no power windows etc. Disconnecting the battery and then reconnecting it returns the car to a fully working state. I drove it without fault for 3 weeks the first time this happened, then the fault returned.

It's been to my local indy Merc specialist who are very well respected and they have read the codes stored. Their suspicion is that there may be a fault with the AAM or the EAM, but as the car starts again without fault once the battery has been disconnected and reconnected, they cannot be certain that those modules are the issue.

I am therefore currently left with the option of driving till I get a 'hard' fault - ie it cannot be restarted - or paying out the thick end of a grand in the hope its those modules.

I'm hoping that someone on here may be able to help shed some light on this and help me diagnose further....

Thanks in advance for any help given

[Greenmantle]

take the battery out
give it a good charge with a ctek charger and then put it back
if the battery is over 6 years old then visit tayna.co.uk and get a replacement. Buy the best you can find.
for the cost of say £150 it could be something simple.
then carry out further diagnostics
can your indie read the sub diagnostics levels which are in German?
Give Dave a ring at MBS - he might suggest something
https://www.mbsofsouthampton.co.uk/

John.

[Classy6]

^ Highly doubt it's a battery fault. Alternator runs the car whilst running and if it was a connection fault the vehicle would have Zero electrical power.

Soon as I started reading I thought it sounded like a random all activity module fault. They are common for similar sounding faults and we replaced a lot back in the day. You will really struggle to get much of a diagnosis over the internet on a fault like this - it's a case of biting the bullet and having it checked. Unfortunately due to it's intermittent nature you're between a rock and a hard place.

It maybe worth considering what the car is worth to you and knowing costs going forward what you are willing to spend on economical repairs, not to be a downer but the old ML's do not age well relating to reliability. The only other option that might be worth toying with is having the module removed and sent away to a control unit repair specialist that can test and inspect the internals.