I seem to recall something about the 4matic system disengaging at about 80mph. I was test driving my "new" car for the first time the other day and noticed the yellow traction control lamp would light up right at 80mph. is this correct?

Also, if I run my car in "test" mode, will it help the transfer case last longer? or will leaving it alone cause it to get stuck?

thanks to everyone for the DIY articles. getting to the blower motor was a breeze thanks to you!

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1967 250SeC
1979 450sel 6.9 (usa)
2009 S550

No, system isn't designed to light the triangle at 80MPH.

The triangle is a warning that the traction system is active. Thinks the rear wheels are slipping.

Are all 4 tires EXACTLY the same circumference? with-in 1/4"

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MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I think so. the car has factory rims and tire wear looks like it's exactly the same on all 4. could it be a sensor problem?

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1967 250SeC
1979 450sel 6.9 (usa)
2009 S550

If the rears are even 1/4" less in circumference than the fronts that can happen.

If you can see 1/4" on 100" you have the best eyes in the world!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

ha! Yes it's true, I don't have superhuman vision.
I was judging by the tire wear, but it's possible that something is indeed different- I don't have too much history on this car. I suppose that if the difference was larger, the light would come on at lower speeds. so, maybe it's uneven tire wear or something!

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1967 250SeC
1979 450sel 6.9 (usa)
2009 S550

Rotate front to rear and try again.

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Gone to the dark side

- Jeff

My light was occasionally coming on at speed (between 30 - 50 as I recall). The steering angle sensor was the culprit.

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07 E350 4Matic wagon, 06 S430 4Matic, 99 SLK 230
retired W210 (x3), W124, W126