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Old 08-18-2017, 03:52 AM
RightFool RightFool is offline
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Join Date: Jan 2017
Location: Henderson, NV/Toronto, ON
Posts: 3
Quote:
Originally Posted by optimusprime View Post
I would go along the lines of a failed OVP relay .
To check it you remove the plastic cover that sits at the rear of your battery .It only pushes in there , so its easy to remove it.
Now your looking for a relay with a fuse sitting on the top .It will have a clear cover that hinges up and will let you replace the fuse if its blown .If the fuse id good ,then pull the relay out ,now give it a shake .Noise of something loose inside will tell you its
shot . Also check the pins on the bottom , thats if all other checks are fine .
Quote:
Originally Posted by Mxfrank View Post
I agree that the OVP relay is suspect. But I disagree on diagnostic procedures. There is NO WAY to test an OVP, at least no way using readily available tools. That includes the procedure in the shop manual, as well as any silly stuff you read here. If the fuse is blown, you can assume the relay is done. If the fuse isn't blown, you can't assume anything....the relay may still be bad. The reason is that the zener or MOV that provides overvoltage protection can be failed, even as the relay continues to appear OK. The "shake method" is a new one, I'm chuckling.

The thing to do is to substitute another OVP. If that isn't the problem, then I'd suspect the crank position sensor.
Really appreciate both of your quick replies to my thread! I was a bit tired when I put my question together and left a really important bit out. The dealer actually sourced an OVP from Mercedes Benz Classic in California and trial fitted it on the car. They ended up finding no change - the car still exhibited the symptoms. I really thought it was that too after checking on these forums.
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