OVP Relay / ABS dash light
 

Every now and then, the ABS light comes on at startup, the motor idle speed increases for until I restart the motor, the light stays off and the engine idle speed is normal.

Is the ABS light related to the OVP relay?

yup.

GregS
'84 300D, 173k
'90 300CE, 164k

Yes it does, it also effects your start up in warm weather.

Check to see if the fuse has blown on the relay, if it has just replace it.

If it hasn't blown, then the OVP Relay could still be to blame, the whole relay may need to be replaced, they run about $50 on Fastlane.
Good Luck

If the OVP fuse is blown?
 

Will a blown OVP fuse cause the ABS light to come off and on at times? The ABS light comes on about once a week, with the same routine. After restart, the ABS light is out for abouta week, will a blown fuse cause off and on problems?

Thanks in advance

Where is the OVP relay?
 

Where is the OVP relay in a 1989 S420 SEL?

THanks again

If fuse blows, then power to fuel and ABS computers will stay off. if symptoms are intermittent but always occurring together then you have a faulty relay. You can either replace it or open it up and resolder all the joints inside - the latter worked for me.

Where is the OVP relay located?
 

Is it in the fuse panel?

Thanks

On my 300SE it is located on driver side
of the engine , all the way in the back. It is a stand alone silver colored relay with a red top - a double fuse "holder" under a clear plastic cover.
Older ones have a single fuse and could be black top rather than red.

Good Luck

Found the OVP Relay
 

Thanks for the advise. I found what I thought was the OVP relay before I started the 420SEL this afternoon and as I started MB the ABS light come on and the engine reved up, I took a pencil and tapped on the relay, and the engine settled back down and the ABS dash light went off. Now I need to ID the relay # and replace it.

I could not have done it without this board.

Thanks again!

don't know if you still need this, but here is the part ID number: P2056-18126 and i was wrong on the price, it's $73 for your car.
Glad you found your problem

jumping in
 

I have the exact same problem. Mine is an intermittent problem as well and idles at about 1500 rpm's when ever the ABS light comes on. every once in a while it will run good then a day latter idles high again. I am almost positive it is the OVP relay I just need to know where the relay is at on an 88' 420 SEL.

Thanks Byfly13