CosmicGrey

Hey, apologies as from my searches I can see there is a whole lot of issues with merc electric seats but I couldn't find anything relating to the issue I'm having.

Today my drivers side seat decided to stop working, I have full leather seats which are also heated, I can still move the whole seat forward/backwards as this part is manual but the recline/raise on the seat is electric which isn't working.

The switch clicks as it was before the issues but there is no noise at all from the motor and nothing seems to happen, I've checked the fuses in the boot and bonnet, all fine. Some forums talk about a third fuse box in the cabin but I couldn't find this (UK model)

This issue also happened a few months ago but rectified itself fairly quickly. So far I have sprayed pressured air into the button to clear the dust and unplugged the seat and plugged it back in, no joy. I've also tried pushing the seat whilst pressing the switch and nothing. Passenger seat works perfectly.

Would be much appreciated if anyone could provide possible solutions!

The car is a 2009 model (pre-facelift)

Thank you!

CosmicGrey

I should probably also say that I absolutely love the car (minus the seat) used to be a bimmer man but this has definitely changed my mindset

MJ50

moved to W204 forum...

Josh.A.Hussey

I would love to help you. You don't hear the motor at all?
No way you have a multimeter and can locate and check the motor voltage as somebody presses the button?

CosmicGrey

Hi thanks for the reply.

Literally no noise or movement when the button is pressed. I don't have a multimeter but could possibly borrow one. I've checked all the wiring and there doesn't seem to be any obvious breaks.

Bit of a odd one really

Josh.A.Hussey

I personally would take a multimeter to the motor and have someone pressed the button to see if there is any activity. If there is activity but no motion, chances are its the motor. If there is no activity, do the same thing at the switch and look for activity. If there is no change of voltage on the output side after the switch has been pressed, chances are it's the switch.

CosmicGrey

Do you know where abouts the motor is & if the seat/trim would need to be removed to access it? This may be a very silly question but does the multimeter just need to me attached to the motor terminals?

Hoping it is something as simple as the switch

Josh.A.Hussey

Can you provide me with you VIN please.

Josh.A.Hussey

Diagnostic1




Diagnostic2




Wiring Diagram




Legend




Picture of motor placement




Seat of MY car. Need your VIN for yours.

CosmicGrey

The vin is: WDD2040082A235258

Thanks in advance!

Josh.A.Hussey

All of the previous images should apply to your vehicle as well. The only one that MAY not is the last.
I will get an updated doc for you but you should have all the info you need. Wiring diagrams and motor placement. The Diagnostics images I uploaded show you what you should be reading from the motors and switches with various paramters (key in and ON or key out or key aux etc.) I think you'll find you have everything you need. Any further troubles I'm willing to help to the best of my abilities!

Josh.A.Hussey

YOUR seat exploded.

CosmicGrey

Thank you! That's incredibly helpful, the part diagrams do seem to match up to my seats. I can't see the wiring diagram clearly on my phone so will look when I get to a PC. I won't be able to work on the car until the weekend so will report back after that!

Cheers again

Josh.A.Hussey

You can always hit the "thanks" buttun! Hahaha

Josh.A.Hussey

Cosmic, how did the seat diagnostics work out after?

CosmicGrey

Hey John,

I didn't get the chance to investigate this weekend as somehow ended up buying the mrs a f20 bmw!

i'll be looking at it this weekend coming, I quickly took off the back panel of the seat with ease exposing the motor etc but couldnt see a easy way to take off the side trim where the switch lies (any suggestions would be welcome )

After thinking about it i think the switch is going to be the issue as its rarely used. We will see!

Josh.A.Hussey

Tomorrow I will check for an easy way to get that off. I would still check motor if I were you. Just for completeness sake.

Congrats on the Bimmer too!

CosmicGrey

Cheers! The BM was a good buy, I've had older BMWs in the past, they've come along way plus no electric seats to break
Unfortunately no multimeter available so instead I loosened the bolts holding the seat in place and checked all wiring.

It's all in good condition but when I drove the car later on my airbag light has come on with a error 'right side airbag malfunction'. Tried to clear the code with a obd2 I have but no faults were picked up. Looks like it's going to have to go to a specialist to get the code cleared so will have them look at the power seat too. Hopefully not going to take me for a ride on the diagnostic!