abs light - PeachParts Mercedes-Benz Forum

lsmalley · #1 12-09-2012, 11:37 AM

my abs light comes on when I start driving forward and never turns off except for when I turn off the car. I took off both front wheels and cleaned off the magnetic contacts inside the wheel hub, I also took off the black abs cover and unplugged the relay and then plugged it back in (battery was disconnected when I did everything) but no change. Is it possible I need a new relay? and if so, could I get one that its from autozone or radioshack or is it benz specific?

Gilly · #2 12-09-2012, 05:31 PM

Well ya know it might just help to know the year and model you are talking about.
In general if the light comes on only once you start moving it's a wheel speed sensor. Depending on the year it may have rear speed sensors or a sensor in the rear diff only.
The other potential for trouble up front is the lead wire itself, this would be besides what you already looked at. Just examining/cleaning them might not really help anything, just because you did that I still would not rule out a sensor. The relays i believe are all automatically check when the car is started (a self-check), if it were one of these relays I think the light would come on without even moving the car.

lsmalley · #3 12-09-2012, 05:37 PM

sorry, same as sig 1990 190E 2.6

Gilly · #4 12-09-2012, 06:30 PM

I don't know why, but I don't see your sig (????). Either your settings or mine I imagine.

EDIT yeah it's my setting, doesn't display avatars or signatures. I think some people had some really huge annoying signatures so i shut them off. I can't remember why I shut off avatars. I might remember some really annoying avatars too, so shut them all off.

lsmalley · #5 12-10-2012, 04:23 AM

any help on the abs light?

Gilly · #6 12-10-2012, 04:58 AM

Ah, no, but I do think the 201 had the speed sensor in the rear diff, as I had already mentioned. I don't think this car had much in the way of diagnostics, like trouble code storing, so would have to test the speed sensors at the control unit. You cold do a visual inspection of the rear sensor as you had done for the front ones. More than likely a bad front one though, they have a problems do to the turning motion of the front steering knuckles and also being lashed down with tie straps and the like.

ps2cho · #7 12-10-2012, 01:41 PM

OVP

Gilly · #8 12-10-2012, 04:44 PM

I would have thought that too except the light comes on only when the car starts moving. If it was the OVP it shouldn't even pass the self-check and the ABS light should be on all the time. Unless there is some weird OVP failure I have never heard of.

lsmalley · #9 12-10-2012, 06:35 PM

Poor OVP gets the blame for everything :-) I actually checked the OVP, fuses good, its 2 years old. Plus I think the car would have a terrible idle and stal as it used to do before it was replaced. I did not check the rear sensor. Where is the location of it? Maybe I'll just clean it up and if I still have the light on I will replace them.

Gilly · #10 12-10-2012, 11:14 PM

Pretty sure it just bolts on to the diff, I think near the top/front. rarely a problem but problem seems to point to one of them. Of course look for obvious wiring damage front and rear.

mbdoc · #11 12-11-2012, 08:26 AM

Just remember, if the problem happens ONLY after moving the car, then the OVPR is not the culprit.

Check resistance values of all 3 speed sensors.

RPM55 · #12 12-11-2012, 10:11 AM

+1 to what MBDoc says. You may also want to twist and move the actual speed sensor harness as you check the front sensors. The raer sensors very rarely fail but it's still worth testing just to be sure.