190e ABS light on / Sensor testing - PeachParts Mercedes-Benz Forum

snakehips916 · #1 01-27-2010, 10:51 AM

My ABS light has been on for 3 months. I can handle that but now its MOT time and it wont pass.
I have replaced OVP relay and car starts fine now (didnt before).
I took the car to a German 'specialist' who said, £50 later, that their machine wouldnt communicate with the ABS! They said it must be the sensors or the ABS main unit.
a) does this sound likely?
b)How do i test the ABS sensors?
Any help is most welcome and I thank you in advance.
I don't have money to throw at this as I recently lost my job. Someone drove into my motorcycle and wrote it off as well so at the moment I have no transport........zzzzzzzzzzz:roll:

mbdoc · #2 01-27-2010, 11:31 AM

1) does the ABS lamp ever go out or
2) does the ABS lamp come on as you start driving?

If the ABS lamp never goes off then either the OVP repay is to blame OR the
silver 6 pin relay mounted on the ABS hydraulic unit is to blame.

If the lamp goes out when starting & then comes back on when moving then
the ABS wheel speed sensors are to blame.

To test the sensors you need a volt/ohm meter.

snakehips916 · #3 01-27-2010, 12:15 PM

Thanks MB DOC.
The OVP is new (i also tried one out of a neighbours car).
The ABS light never goes out.
What figures in ohms or volts am I looking for in the sensors?

mbdoc · #4 01-27-2010, 12:32 PM

If the ABS lamp never goes off then either the OVP repay is to blame OR the
silver 6 pin relay mounted on the ABS hydraulic unit is to blame.

Try a relay on the hydraulic unit.

d.delano · #5 01-27-2010, 03:56 PM

Sorry about your motorbike, and sorry you have to pass UK MOT with a 17+ year old car. That's a challenge in and of itself. You guys have some serious regulations.
Something that MB Doc hasn't mentioned is the contact ring behind the steering wheel. I'm not an expert, but I do have a 190E and the ABS light flickered on and off, and sometimes stayed on as I drove it. This car sat in a garage for five years without having been driven (it's my father's out on loan to me). I know that flaky connections can be flaky for a while and then just go out after a certain point. You could try disconnecting the battery, removing the steering wheel, and cleaning the contact ring. Might be as MB Doc suggested and probably is, but checking this is cheapest. Good Luck

MattBelliveau · #6 01-27-2010, 03:59 PM

Pull the bulb...

snakehips916 · #7 01-29-2010, 11:41 AM

OK. I have checked all pins in ecu and relay connections on ABS unit. OVP is still fine. Took the car for a spin and tried several emergency stops. ABS is working but ABS light is still on.
I checked the front sensors with an ohmeter and the left one is reading 987 ohms and the right one is 976 ohms. It is getting dark so didnt check rear sensor. I presume they were the sensors........the connections looked like large tv aerial connectors....one either side of the car mounted by plastic clips!
I checked battery is charging and got a reading of 14.05 volts
Any ideas what else it could be?

mbdoc · #8 01-29-2010, 12:24 PM

I guess you haven't gotten it.

IF the lamp NEVER goes out..it isn't a sensor problem!
The most likely problem is the voltage relay ON the ABS hydraulic unit under the black plastic cover.

Of course the overvoltage relay must also be good, and I know you think it is good.