1995 E320, 198K, runs great except for an ASR issue I am having.

While acceleration hard, the ASR warning triangle lights up and cuts my power, and even applies the back brakes. It will usually do it from 50mph up with spirited acceleration. Also, sometimes I notice that when I let off the gas after it kicks in, the car will brake violently and pull to the left or right, almost dangerously.

The car's ABS also occasionally kicks in during normal routine stops. The cruise control sometimes works, but mostly doesnt.

The car is not reporting any codes, on any of the different pins. The tires are all the right size, all have same tredwear, and all the correct pressure. Im really dumbfounded as to what it could be. There is no dummy lights on in the dash. Curently I have disconnected the drivers front ABS sensor so that the car is drivable.

Ive replaced the brake switch and that did nothing. The car has a new engine harness and also a new EA harness.

Im wondering if it could be a bad OVP relay or an ABS sensor? What should my next course of action be? Im surprised the car is not reporting any codes.

Thanks to all who respond...

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

Check the circumference of ALL 4 tires closely, even 1/4" difference can cause that!

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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 did. They are all brand new. To add insult to injury, I even took the brand new michelins off my 400E and put them on it, same thing.

Not sure if this means anything, but when it was on the lift, I put it in drive, and the ASR immedietely kicked on and was braking the rear wheels (like it should be). My only concern was that I wasnt on the gas. Shouldnt ASR be inactive until the system recognizes the driver is on the gas. Could the sensor be bad on the gas pedal?

thanks!

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

Check the WSS ....specially as you are having ABS lamp as coming to a stop.

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A Dalton

How do I check the wheel speed sensor?

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

You can start with a DMM and spin the wheels..also ohm them for spec.
You can also pull them and see if they are full of crap and metal filings.

There is a good post about them from a few weeks ago..do a Search.

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A Dalton

You need to look at the wheel hub "teeth".

Even a nick can cause that speed sensor issue.

__________________
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

The teeth look all uniform, albeit highly corroded. I dont know if they are worn down or not, since i dont have a spare to compare it to. If this issue is caused by an excessive spacing gap, is my only option to get a new hub, and hope the teeth close that gap, or is there something I can "rig" or machine to close the gap.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

You could try switching hubs side ro side or even switching one from another car.

??? is the ABS light also coming on?? IF not then the sensor may not be causing the problem.

__________________
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

The ABS light is not on, however through the use of a multi-meter, both rear and left front ABS sensor outputs are relatively the same for a given speed. The right front one is the oddball, producing almost zero output. Why it isnt triggering the ABS light instead of seeing it as a locked up wheel is beyond me...

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

The main factor for sensor output is spacing, so you have worn down reluctor teeth or a bad sensor.

A scope is nice when you do these b/c then you then see what the Module is actually seeing [ which is why I posted the article]
An ohm value only tells you the sensors coil ohmage for shorts or open circuit and a volt reading tells the Average amplitude. But a scope will tell you every single sine wave chacrteristic of every reluctor hall effect on the sensor. That is what you want to know.
I suspect reluctor height has deminished, just from wear and road rash/ruct. But do not over-look a possible bad sensor...Does the new one match up measurment-wise w/the old one.

Also check that the wheel bearings are not loose..

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A Dalton

Arthur,

Thanks for the advice. I agree a scope would be key. I nor my independant have access to one at this point. I did not put the old sensor next to the new one to compare. They looked the same to me, but that might be in order.

I redid the wheel bearings earlier this week before I put the new sensor in. They are nice and tight with new grease.

A local salvage yard is sening me a good used hub today that im going to put on. It was relatively inexpensive ($36) and hopefully will put an end to this madness. If that doesnt solve it, then my ideas are exhausted.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

FIXED!!!

The new (good used) hub fixed the problem. Turns out the corrosion did knock some height off the reluctors.

Thanks too all that helped, especially Arthur and DOC.

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93 300D 2.5 Turbo, Black/Palomino 273K
09 E350 Black/Black 41K

I've often thought about a scope. Can one be had inexpensively? Perhaps used? Any links to an example?

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Best one is an LS2000..they are DSO and user friendly..and altho they origianally were around $2 grand, you see them on ebay all the time for a couple hundred. Try and find one that also comes with the ign pick-up.
That scope will pick up anything on automotive systems.
Unfortunately, the days of diagnosing with a DMM and a test lamp are disappearing b/c of the technology and a DSO is now just commonplace in any shop. But the upside is now you can buy one for cheap..and once you own one , you will wonder how the hell you got by w/o it.
You can look at any sensor and diagnose it in 30 secs w/o that " WONDER if 'dis is gonna' work " feeling you get as you buy an expensive part ..so, it pays for itself.
I see many post here where the poster says his Mechanic does not have a scope...RUN...that puts him in the same boat you are in...Guessing.

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A Dalton