W163 / ML seat occupancy sensor problems!

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miggit

Active Member
Joined
Mar 25, 2016
Messages
102
Location
Milton Keynes UK
Car
2000 ML270CDI Manual
Hi all,

I suffered the dredded Airbag light permanently on earlier this year, it was caused by the sensor mat in the passenger seat.. So I got hold of one of those seat occupancy sensor / emulators and fitted it. At first all went well, the light came on with the ignition, flashed once and then stayed off, Result!! This went on in this fashion for a couple of weeks, and then it would flash and stay on... normal service resumed, D'OH!!

I plugged the car in to the box of tricks and deleted the codes and tried again.. light still on, so the emulator has failed.. I'm now left wondering where to go now.. try another emulator? was it a dud, or did the car fry it?

I've just had the seat out, hoping that I'd find a broken wire or loose component in the emulator, but all appears to be OK, other than it don't work :( I'm now at a loss, has anybody suffered a similar fate??

I will admit to buying a Ping Pong special, could it be at fault? But seeing how 99% of all electronics come from China and normally from the same factory with different labels to reflect the different prices.. is there a truly bomb proof emulator?
 
Could the wiring under the seat be at fault? Check it carefully, especially the connectors and where the wires enter them.
 
Hi,
I have fixed a few issues with occupancy sensors, 1 VW Passat, 2 ML's, 1 Audi and my C230k that I had, and never had to replace the mat itself.
Everytime it was a dodgy connection in the plug.
All I did was take the connector apart and tweek the sockets with a pair of pliers to tighten them up.
I first thought about this when I was told about the apparent approved Audi repair to a seat air bag was to cut the connector out and solder them back together and thinking this was just a bodge thought I would try just tightening up the socket pins of the connector and it worked.
The MLs the light was intermittent on both of them once the connector was tweeked light extinguished never came back.
A loose connection car side of the emulator could explain why it is not working it could also mean that your original sensor mat is ok
 
I suppose that it could be a corroded connector, although the connector didn't appear to be in a bad way.

What was happening, if the seat was used the light would come on and then stay on for a few days before going out... until the next passenger... but the reset time was increasing with every use. I just assumed that it was the mat breaking down and having seen the cost involved in replacing it, decided to try and find a work around.
 
Corrosion wasn't the issue on any of the cars I sorted,it was the socket pins worn just pinching them slightly with pliers sorted it.
 
Well I've had a busy day and got nowhere:(

First I hard wired the loom to the seat mat (bypassed all the plugs), that put the light out for a few seconds... and just when I thought I'd done it.. it came on again. Read the faults, all passenger seat sensor ones, cleared them and then hard wired the emulator to the loom... that didn't work either... but I did go from 12 faults to 4... so I suppose that I've had a 66.6% success rate:confused:

The main fault is saying that there is a positive short on the data line from the seat.. got a feeling that the emulator is fubared along with the seat mat, D'OH!

Now do I try another ping pong special.....
 
No, not unless you enjoy your work
 
Right I've bitten the bullet and ordered an EU made sensor bypass with status LED's, it also comes with a seat belt bypass... just wondering if that is the problem with mine? Hopefully I will only be removing the seat 1 more time!
 
Why are you bypassing a safety system?

Don’t those sensors determine whether the air bag is triggered?
 
I thought the emulators prevent the seat pad indicating an empty seat, thus always allowing the passenger airbag to trigger on an impact.

Thus, the bypass is of the mechanism to prevent that airbag being triggered when the seat is empty.

Guess you must then remember never to fit a baby seat.
 
another route is go to someone withs SDS, code sensor to disabled state, leave sensor unconnected and be happy. Same result though, no chance for child seat then. Dangerous if reselling the vehicle without a note.
 
Yes my Airbag will go off regardless of any passenger... but I'd rather that than no airbag deployed. Plus it gets rid of that bloody orange lamp that blinds you at night....why don't they dim with the lights on??

As for the implications of a child seat, I can assure you that there is no way one will ever be fitted in my car... and I can't see anybody being stupid enough to buy my car for anything other than scrap... it is just shy of 275K and by the way it's going I can see me putting many many more miles on the clock. It's a working car, and I can't afford a replacement except another ML W163, and as I nearly ironed all the niggles out of this one Why Change? And lastly it is a manual 6 speed, which is not the most common ML for sale.
 

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