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Old 05-08-2003, 03:32 PM
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Join Date: Apr 2003
Location: Watertown, MA
Posts: 23
OVP Fuse


My car idles rough for about five minutes after starting --up to 1100, but settles down at 5-700 after five minutes, approx. It also jumps up from 1100 during the initial five minutes if I shift out of park to drive or reverse. I searched a bit and found the ovp to be the one item most mentioned in connection with this kind of issue.

I checked mine out and found that it has two fuse slots but only one is present. Should both slots be filled?

And how do we test this to determine if it defective?

"no one has always been there"
---Robert Nesta Marley
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Old 05-08-2003, 03:38 PM
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Join Date: Jun 1999
Location: Surrey, Beautiful British Columbia, Canada
Posts: 750
there are two slots, i'd put in new fuses and
see what happens.

Prayers bring forth enlightenment.
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Old 05-08-2003, 04:12 PM
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Join Date: Apr 2002
Location: Surrey, Uk
Posts: 254
Bad OVP relay usually brings up ABS light if fitted
Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)
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Old 05-08-2003, 04:22 PM
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Join Date: Apr 2001
Location: Dallas/Fort-Worth
Posts: 5,711
Different MB models share this same part, hence the two slots for fuses, depending on the electrical configuration of the particular vehicle.

You should only have one fuse...adding another won't change a thing. Pulling the existing one will make your car run REALLY bad!

You may have to search other threads, but the defective one has a particular part # and is manufactured by Siemens in Austria. The replacement has a different part #.

But I'm not sure the OVP is the cause of your ills...and the ABS light does not necessarily illuminate when there is a problem...
2009 ML350 (106K) - Family vehicle
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Old 05-08-2003, 04:45 PM
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Join Date: Mar 2003
Location: Southern California
Posts: 2,068
Your engine has an automatic idle stabilization system, which should maintain a constant idle speed. When you shift from a drive gear to park the removal of the torque converter load will momentarily raise the idle speed until the valve closes down.

I think the OVP gets blamed for a lot of problems that it's not responsible for. Several have reported that removing and cleaning the idle speed control valve cured or mitigated idle problems. You should also carefully check the rubber air supply hoses into and out of the valve for cracks or breaks as several have reported them in poor condition. One other thing to check is the function of the throttle vavle switch and throttle linkage microswitch, and I found that partially disassembling, cleaning, and lubricating the throttle linkage solved a flaky idle problem I was having about a year ago on my 2.6.

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Old 06-05-2003, 01:57 PM
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Join Date: Apr 2003
Location: Watertown, MA
Posts: 23
End Of Story

I cleaned the idle control valve with about 1 can of carb cleaner and it idled much better than before. This was the right thing to do.

Now, as you might know already from another thread of mine, the car died on me and is in the shop for repairs. Unofficial list of items replaced to date are: mas, ecu, and ovp. Stay tuned to the other thread for the end of this story.

Thanks for all the great pointer's.

"no one has always been there"
---Robert Nesta Marley
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