Hello all,

My car is a late 2019 S560 Sedan.
Now 4.5 years old with 49,000 kms (about 29.5k miles).

Yesterday I got 3 warning messages pop up and they do so now every time I start the car.
Lane Keeping assist inoperative.
Blind spot assist inoperative.
Acting braking assist inoperative.

After referring to a number of threads in this forum I went out and replaced the Auxiliary Battery. The batter shop did test my old one. They said "it was still ok but not great".

Having replaced it, the 3 warning messages are still there.

It could be sensors (radar or otherwise).
It could be unclean sensors (My car is clean, immaculately maintained and all my reverse parking sensors and cameras, including front parking sensors are working.

I have a number of questions and hope someone can answer or provide thoughts please.

1. Do I need to drive the car for tens of miles so that my car has a chance top relearn and note that there is a new Aux Battery >
2. Do I need to drive the car for the Aux battery to get to full charge before these warning messages get reset?
3. I read that sometimes one inoperative system "on the same CAN BUS knocks out other systems on the same circuit ??

Any thoughts and help much appreciated....

And.. I will try to get the car to an indy for a diagnostic run...

Thanks all

 

Could be many things, you need proper diagnostics. Dealer, specialist or Chinese Bluetooth dongle.
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Do you have moisture in your headlights? May have damaged a controller.

 

Thank you for replying VII.
Yes, I will do my best to get an OBD2 (Indy dealer or main dealer) run diagnostics on the car.

An update: I just drove the car on a 70 Km round trip and the messages have not cleared.

Also, do you or anyone else recommend a Mercedes Sclass compatible OBD2 diagnostic tool? Waging Chinese dongle did you mean ? are you able to provide a little more detail Please ?

 

No Moisture whatsoever in the headlights.

Are the controllers in the vicinity of the headlights ?

 

A thinkdiag from Amazon would be able to give you exact codes, it's about 80-100. There might be others that work but that is the only one I have tested that I know would work.

Do not get a generic $20 OBD as that only covers generic engine codes.

 

I started getting "Active Blind Spot Detection Inoperative" back in December when we had a strong cold front and lots of rain. Kept popping up for several weeks afterwards and now has gone away. I went around and cleaned each of the radar points and the cameras, but I don't think that had anything to do with it.

Assuming it's another electrical oddity like the windshield wipers making a single wipe for no reason on a hot, sunny day.

 

Thank you Tom.
I shall clean all sensors on my rear and front bumpers. Lets see if it makes a difference.

i can confirm that all cameras are working.

 

An update .... I may be getting closer to the problem....
I am now joining up some dots ....

A week ago my car had a "bump" to the rear passenger side corner of the bumper. There was some paint left behind from the bumping car and numerous scratches. The other cars bumper was considerably more damaged and the bumper pushed in !!! So.. some reasonable force.

It is after this that the 3 warnings (Blind Spot assist, Lane keeping assist, active brake assist) appeared.

My research here and elsewhere (Thank goodness for Youtube) indicates that this could be a radar sensor problem).
it could also be a radar control module that connects to these bumper sensors.
It could be sensor wiring behind this sesnor
It could be a damaged sensor, although I see no damage on this sensor and don't believe the sensor had any damage, scratches etc to it). I have also cleaned all rear sensors.

I can also confirm all sensors including this particular one are operating when I reverse and get close to an object. I tried this several times. The rear camera is also working.

Some owners state that in extreme weather (extreme cold and wet mainly) they have had intermittent problems. I can confirm I am in Australia and no extreme COLD weather (although sometimes we wish it - Its 37 degrees Celsius today)...

It may also be that once this momentary impact caused a sensor problem, the inoperative code was established as a fault and it MAY BE that the code needs to be cleared. I am given to understand that once a code appears on a CAN BUS "it knocks out other systems on the same circuit / bus".

Finally, it may be coincidence that the rectangular radar module mounted to the inside of the Chassis / Bumper is faulty.

Or none of these ....

I am just about to order the Thinkdiag OBD2 Diagnostic tool which this Forum User VII has used and it works with his Mercedes ... The price for this in Australia is AUD $129 and seems like a no-brainer .... The Thinkdiag OBD2 scanner is bi-directional and hence can read and CLEAR fault codes...

Somehow ... methinks this is a dealer visit .....

 

Update 2 - providing more info as I find it .... in the interest that it helps someone else ...

One user on this forum had the 3 warnings I have (Blind spot assist, active brake assist and lane keeping assist) His dealer replaced one of the front speed sensors (near the front wheel) and all three messages disappeared. He was told this speed sensor was faulty and as it is a :"safety issue" then "it was shutting down the other "safety systems" ....

Another user confirms that he had the same issues on his S63. On diagnosis at the dealer it turned out to be an issue of a rear bumper radar control module. The dealer mistakenly just changed the radar module and the issue persisted. They then found that the radar module itself was not the problem but the plastic bracket holding the radar module tight against the inside of the bumper was brittle and had broken away. The user reports the dealership just taped the radar module tight with duct tape and this instantly solved the problem .... Go figure !!!

 

Final Update ...

I decided to risk a diagnostic at a European Car Workshop.
I was there present watching while the tech connected it to the OBD port.
The technician used an AUTEL Diagnostic tablet.
It showed up a rear passenger side "radar malfunction". His experience told him no "SCN Coding required. He opined that the radar sensor had "a little bit of a shock when it had that bump to the bumper" and so no software had changed. Therefore there was no reason to invoke the "SCN Coding" sequence.

The fault code had notes. It stated that the Radar needed re-adaptation.
So he invoked the adaptation sequence. He also did a quick clear of all existing faults.
Result - the warning messages disappeared.
Further adaptation sequence notes recommended the car be driven for 20 kilometres so that the radar could re-learn and re-adapt itself.

On the motorway, diving at about 60 miles per hour, centre lane, I noticed after about 10 km of driving, the blind spot assist red triangles came back on as cars approached me on the right and left. The Lane Keeping Asset icon came back on (green) and all messages have disappeared.

Make of this what you will and hope this helps other car owners...

My thanks to the forum for helping me navigate this conundrum.....

 

Interesting ... good to know there is a 're-adaptation' function for this system. Just out of curiousity, how many labor hours were required to do this?

 

From driving the car in to the workshop to hooking up the Autel tablet & completing the diagnostic work - 4 minutes. !!!

A local dealer wanted $AUD 500 !!!