I have a 1994 W124 E220 Estate
I have a weird problem with the ABS light, I will describe the symptoms.
1. Start car, ABS system passes all diagnostics and light goes out.
2. I drive for about 1/2 Km, and ABS light comes on and stays on.
3. I stop somewhere for about 10 mins.
4. I start car again and set off, ABS light does not come on even after
many miles, BUT when I brake the ABS cuts in at about 5MPH irrespective
of the road surface conditions.
Anybody had this problem and knows what the fix is.
Best guess? Worn brake pads. You're sitting still and light goes out as it
should, so the ABS system is probably alright. Good thing as that is an
expensive fix. You drive for a bit, and I am assuming you touch the brakes
at some point, and the light comes on and remains on. It is probably
telling you, in its' own way, that you need brakes. You drive again and
when you apply brake, the light comes on again....I would check the wear on
the brake pads. If it was the ABS system itself that was going bad, it
wouldn't pass the diagnostics when starting, like you mentioned, and would
There may be a boatload of sensors and such that could be acting up, I
wouldn't know about that, but the brake system is fairly straightforward, so
I will hang in there with my "best guess". Let us know what it was when you
This sounds more like an ABS pump valve or sensor rather than worn pads. I
suggest that you find a good independent that will service ABS (some will
not and tell you that ABS is only handled by the dealer) and see if they can
diagnose the problem. *Sometimes* they can free up a stuck valve by
exercising the unit via computer - I once had this done to a Honda for $75.
It fixed the problem for about six months or so. I later found out that
many Hondas had a known issue with the ABS valves. Another potential
problem (and one that is relatively inexpensive to fix) is the sensors on
the wheels themselves. On some cars they are optical and get dirty over
time and simply need to be cleaned. Considering the season (winter) and
your location (UK) it's quite possible that slush has pushed dirt into the
brake rotor area which is where I believe that these sensors live.
sounds like a worn or dirty speed sensor lead .The fact that the abs
pump pulsates the brake pedal at low speeds ( 5 mph ) indicates it has
a weak signal and it cannot detect actual veh speed. The pulsation of
pedal rules out brake pads .
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