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S124 a 1989 W124 230TE originally from Germany
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189 Posts
Discussion Starter #1
Hi folks
I cleaned the two front ABS sensors during a front wheel bearing repack.
The ABS light turns on with ignition switch on then turns off as the engine starts only to turn back ON (and stay ON) at around 20 kph (around12 mph).
Any ideas as to why ??

Denis
Mennecy
France
 

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Premium Member
2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,014 Posts
It is probably insufficient voltage from one of the ABS sensors. The ABS controller checks the resistance of the sensors at start up and then checks for sufficient voltage once the car is in motion and exceeds a certain speed. If the resistance check fails, the ABS light is turned on immediately. At speed, if one or more of the sensors is not producing sufficient voltage, the controller turns on the ABS light (which will remain on until the system is power cycled). Check to make sure you didn't damage one of the sensors when you cleaned them. Edit: Also make sure that the sensors are properly seated in their bores and that the reluctor tines on the hub are also clean.
 

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Registered
S124 a 1989 W124 230TE originally from Germany
Joined
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189 Posts
Discussion Starter #3
It is probably insufficient voltage from one of the ABS sensors. The ABS controller checks the resistance of the sensors at start up and then checks for sufficient voltage once the car is in motion and exceeds a certain speed. If the resistance check fails, the ABS light is turned on immediately. At speed, if one or more of the sensors is not producing sufficient voltage, the controller turns on the ABS light (which will remain on until the system is power cycled). Check to make sure you didn't damage one of the sensors when you cleaned them.
S

So getting two new front sensors (equal resitsance) should fix the problem right ?

Denis
 

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Premium Member
2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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1,014 Posts
In reality there is probably only one bad sensor on your front wheels. The problem is that there is no easy way to tell which one. Replacing both, of course, should do it assuming they are installed correctly and the reluctor tines on the hub are clean (did you clean these as part of your wheel bearing service?).
 

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Registered
S124 a 1989 W124 230TE originally from Germany
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189 Posts
Discussion Starter #5
Yup ! I cleaned up all the teeth. Problem is that I should order both sensors. My car will NOT pass inspection if the ABS warning light stays on. I remember that those parts are "still" inexpensive from german OEM suppliers ...but that could change...

Denis
 

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'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,176 Posts
Very sound advice from Flooby, as usual. If they have some age anyway, I don't see that as 'throwing parts at it'. I would have suggested swapping in a JY ABS module if you hadn't said you just cleaned the sensors. Playing 'detective'......something got moved enough in your cleaning efforts to cause insufficient voltage/failure of the sensor(s).

Gotta love working on these old-ass cars........

Kevin
 
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