W203 Water Ingress in Boot - ESP fault

[Hustler]

Hi Guys

I've long had an ABS/ESP/BAS malfunction warning on my dash and discovered about a year ago that it was probably something to do with water getting into the trunk/boot but I didn't know exactly where.

After doing some Googling yesterday, I decided to strip down the flooring material on the boot and check out that area of the boot.

Here's how it looked:



and here's a closeup:



As you can see there's been some corrosion on the connectors and copper wire of the speed sensor connection part. This was the only area that was slightly damp, the rest seemed pretty dry having possibly dried over some time.

I've doused the area with WD-40 Contact Cleaner numerous times and tried cleaning the area and contacts of the cable and the speed sensor as best as I could hoping that it will work. Also completely hairdryed the area so it's completely dry now.


However, I've driven the car around the block a few times but the ABS/BAS/ESP error has not gone so I was pretty disappointed. Also done the lock-to-lock reset trick but that doesn't work at all either.

I'm hoping the yaw sensor is perfectly fine because apart from the white spotty rusty-like casing, the unit itself seems completely dry and the wiring to the sensor is also completely dry and looks like new.

What I wanted to know is whether I need to take the vehicle to the garage and have the error reset or should the error message just extinguish itself?

Also, is there a way I could test the connection with a multimeter (If so, what setting do I put and what results should I expect)?

Finally, is there anything else I should do that I've missed? I was thinking of taking the wire out and recutting and then re-inserting back into the plastic connector but pulling the wire out of the connector seems to require a lot of force so I imagine putting it back in would be even more painstaking. :| Something tells me the contact cleaner and scraping the connections with a small safety pin hasn't done a good job:



Would really appreciate some help as it feels like I'm close to getting it fixed but I don't know what I should do. Hoping the experts here can give me some advice

Thank you!


I should mention that i'm no mechanic and have limited 'knowledge 'in vehicle troubleshooting and repairs. :Oops:

 

[television]

By rights that ECU should only affect the ESP, but water is a strange thing in that it can take out other circuits, like the Speed signal. Have you tried the car with this ECU unplugged.

 

[Hustler]

By rights that ECU should only affect the ESP, but water is a strange thing in that it can take out other circuits, like the Speed signal. Have you tried the car with this ECU unplugged.

Hi Malcolm,

By 'ECU' i'm guessing you're referring to the silver box in the pic above? I've not tried driving without that unplugged. Will try tomorrow and post what happens as it's close to getting dark soon.

Oh, and I've found a way to take out the wires/pins from the connector so will try that tomorrow as well.

Thanks

 

[television]

I am just hoping that the water is pulling down the ABS.

The ABS is the heart of the system, the BAS rides on top of ABS, and ESP uses the BAS.

With it unplugged I am hoping that it will just say ESP fault.

 

[Hustler]

I am just hoping that the water is pulling down the ABS.

The ABS is the heart of the system, the BAS rides on top of ABS, and ESP uses the BAS.

With it unplugged I am hoping that it will just say ESP fault.

Just unplugged the connector (circled in red) but am still getting ABS light and ABS/BAS/ESP Visit Workshop message on the dash.



I've cleaned up the connectors on the connector part for the speed sensor and visually it looks clean and OK. Don't know how I can check the connectors with a multimeter as I'm not too familiar with using one. Would appreciate it if anyone can offer any advice as to what I can do next.

Thanks

 

[television]

At this stage it would be far better to get a fault code read out of the problem.

That ESP control is probably scrap, it is looking like there is an ABS fault, it was worth trying it unplugged, as that cost nothing. Short of studying all the diagrams, it is not possible to see where this joins in and the effect on other parts.

 

[WG M-B]

Is that not the yaw rate sensor ?
The esp control module should be bolted to the front of the hydraulic pump in the engine bay

 

[television]

Indeed it is the yawl rate sensor, though I think it is useless now I still feel the fault is further back, we know the BAS has a speed signal. It does need to go on STAR, well thats what I think

 

[Cole@MBS]

This is a really common fault, your find the Sensor is green inside due to the damp, star will show no comms with yawl rate sensor, hence the fault showing on dash, its about £400 for a new sensor and sometimes needs plug and loom depending how much water damage there is........

 

[clubleya]

Hi, I had the same problem and got a new sensor from german ebay for £40, I also had problems a few years later with a speed sensor fault that wouldn't clear and after loads of messing about I found one of the wires in the loom leaving the sensors had been nipped but the black cover at one of the edges and was giving a bad connection. I cut it and reconnected it and haven't had any further faults.

Really need to get the codes check and see if they will clear, I have a carsoft interface that works really well with the ESP module in my car

 

[M80]

Re: the water ingress,
I've found that water travels past the rubber seal that sits on the lip of the body.
Even if the seal is pressed to seal by the closed boot, water can pass around the inside of the lip on the vertical runs.

I've cured these issues on 3 of mine by removing the seal,
running a bead of silicon sealant around the whole of the inner part of the seal,
then re installing.