W-124, 1990 300E. ABS light comes on at random. When it does, there is an immediate and significant drag on the engine, whether at speed or idling in Park, that continues until the light goes out. Sometimes it stays on a few seconds, sometimes much longer (maybe an hour). It might do it 5X a day, it might not do it for a week. Any thoughts?

Do a search for Overload voltage relay or OVP relay.

Commonly, this is ABS sensors problem behind the front wheels.

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300SE 1988 <------- Sold
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Where is the OVP relay? I looked through the threads and saw many mentioned but couldn't find my specific vehicle.

What do you have?
300E 2.6
300E
300E 4-Matic


PART NUMBER SEARCH RESULTS WITH PRICES
Vehicle 1990 Mercedes Benz 300E
Part: Overload Relay
Note:
Aluminum cover with bracket : contains (2) 10 amp ATC fuses on top .
Year: 1988-
P2056-18126 Overload Relay Germany IN STOCK $76.02

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1VE10RDJ21W315L5T6&year=1990&make=MB&model=300-E-002&category=All&part=Overload+Relay

But when the engine falters and loses performance when it comes on then it very well may be the OVP because that triggers the light and also supplies power to the idle control valve and EHA, components that affect performance.


The OVP relay is located behind the plastic panel firewall, behind the battery. It has a fuse(s) on top.

It's the 300E with the 3.0 liter engine. And thanks for the location info. I'll check it out. I'm assuming that it's a replace item unless one can resolder the connections inside?

We went thru this...
The opinion here is look at the date stamped on the OVP... older than 5 years... buy a new one... in doubt.... just buy a new one.
It cured our ABS/SRS/Lights and stalling in one hit!

Look here...
http://www.peachparts.com/shopforum/showthread.php?t=154029

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2009 Mercedes ML320 Bluetec

Man, it sure sounds like the same problem here. I was only posting the ABS light because the SRS light and the stalling are so rare and the ABS is the one that drags on the engine. I had no idea all those could be related! I see where the relay costs in the $75 range so that would be a bonus to cure all that for that price. Thanks for the help. I'll check it out tomorrow or Fri and post findings.

Yep,
My money is on the OVP... when the ABS light came on our motor bogged down and did not run well... and stalled if you stopped too.
Thats why the previous owner sold it to us!

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2009 Mercedes ML320 Bluetec