ABS light intermittently on and rough tickover
 

W124 1991 300D auto 206,000 miles :
Abs light comes on and stays on run it for 10 -15 miles goes out,stop it and same again.when its ticking over engine labours and shakes the car to bits but when lights out its fine

Heard and read about low voltage's will cause light to come on,so when its runnig for 10 miles or so battery is full charged and all ok?? battery is less than 12 months old and charges at 13.7v.is it possible to just change brushs on this type of alternator or is it service ex unit.

wheel sensors...how common are they to failure
tyre pressure's and wear .if they are causing the problem fault it would be there constantly.. so i cant see that being the problem.

wet weather.. water on sensors/cranked sensor.noticed problen has been more or less there since rain

can anyone explain the roughness in engine while light is on

thanks
Rob

If your car has an overvoltage protection relay, and I imagine it does, it could be on its way out. In the LHD version of that car the relay is tucked between the battery and the firewall. Maybe look there first.

The relay looks like this -

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1UF05A51E1XD0QGLZL&year=1991&make=MB&model=300-DT-003&category=All&part=Overload+Relay

Sixto
93 300SD

found the overvoltage protection relay after much searching..
removed it from car cleaned ,stripped it down ,cleaned the fluff off solder

tested.....no better :mad: tap it slightly abs light out engine returns to normal

left it loose in battery box ie on its side tested stationary and light off refit to bracket back on


think new one is needed

thank you

Clean (or change) the ABS sensors on the front wheels. 100% they are causing this problem, I faced it on my 560SEC 1989 W126.