Rain causing electrical faults

[Lorathexplora]

Hi, looking fit a bit of help. My 2006 ML320 develops some specific electrical issues when it rains.
I'm used to tracking faults down on my old cars but this is my first Merc and it is the most complicated electronically so just want some guidance.
When it rains the same few things go haywire:
The parking sensors error with their two red lights and a beep.
The rear passenger door lock locks and unlocks quickly several times.
I intermittently lose wing mirror indicator.

There is clearly water ingress somewhere and I'm about to start with fuse boxes etc
Any tips or advice (things not to mess

 

[W1ghty]

Hi, looking fit a bit of help. My 2006 ML320 develops some specific electrical issues when it rains.
I'm used to tracking faults down on my old cars but this is my first Merc and it is the most complicated electronically so just want some guidance.
When it rains the same few things go haywire:
The parking sensors error with their two red lights and a beep.
The rear passenger door lock locks and unlocks quickly several times.
I intermittently lose wing mirror indicator.

There is clearly water ingress somewhere and I'm about to start with fuse boxes etc
Any tips or advice (things not to mess

Maybe check the base of the windscreen drains are clear , there is probably an engine bay fuse box up there as well .
Check for wet carpets , water in the boot wheel well .

 

[Smart320]

Have a feeling that the rear quarter light seals are prone to leak and that there is a SAM on the offside which can get wet . I could be completely wrong but seem to remember reading this when I had an ML . Am sure an expert will give you the ‘ real ‘ answer

 

[MikeInWimbledon]

You've had good advice here.

My addition is that, as Smart320 says, back in the day, people had problems with the rubber seals on the rear lights failing and letting water in, which then makes its way to the SAM at the back.

In general, as has already been said, hunt for signs of damp anywhere it shouldn't be.

Kitchen roll is your friend. It'll tell you if there's damp in there, beyond the moist bits carried in on your Manolo's.

If you do find water sneaking in, dry out as much as you can, (a hair dryer's good, but not if it's raining) and put some masking tape (a fiver from Amazon) on the joint for the few days before you can get a proper fix done. It might look a bit Micky Mouse, but better to stop ingress before it does any more expensive damage.

And switch the air con up to help dry out the interior. Might sound obvious, but it will help.

 

[Lorathexplora]

Amazing thanks guys!

 

[BlackC55]

Or water is getting into the floor where the battery sits.