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  #1  
Old 09-01-2002, 06:27 AM
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Talking OVP relay failure is suspected, bypassing help needed

After about 2 weeks of owning my W124, 1989 230E and enjoying a smooth Mercedes ride the car finally died today. In these 2 weeks it showed the following simptoms of a bad OVP:
1) The car hard to start when hot. Had to crank 2 or 3 times with intervals of 1 minute then it would start.
2) The ABS lamp came up 3 times while driving in the city and on highway.
3) When the engine is cold the car had idle problems. I had to keep the gas pedal pushed a little for about 1 minute in order to keep the engine running.
4) and finally it did not start after a short stop at my teacher's house today.

I tried 10-15 times to start it, waited 1 hour to let it get cold but still the car would crank, pick up rpm like it is starting then it continues cranking as if there is no gas in the tank. I tried to roll the car down the hill but it did not start. The gas tank is full, and the gas filters are new.
My question is, is there any way to bypass the OVP and start the car? The nearest Mercedes service shop is about 300 km away from the place I live and I need to figure out the way to start the car. I would appreciate any advice on how to deal with this issue.

Hurshi
1989 230E, very nice looking (pictures coming soon!)
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1989 230E, 8v, 166.000 km, updated to 94/95 trunk & hood
2002 Daewoo Nexia 50.000 km
Sold:
1987 VW Jetta GLE 16V, Recaro seats
1982 Volvo 240 DL (lovely car!)
and few more american cars.
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  #2  
Old 09-01-2002, 09:14 AM
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They usually will start right up if you just tap the OVP with a screwdriver handle...
Give it a try. Behind battery panel-remove plastic cover - tall aluminum can w/fuse on top...
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  #3  
Old 09-01-2002, 12:17 PM
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The OVP relay is not a likely problem in a no-start on your car. Some of the other symtoms could be attributed to OVP but the KE system does just fine warm without OVP - VERY GOOD limp home characteristics.

I would look to the fuel pump relay. But look is what you need not a crystal ball. You need to find what is missing.
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  #4  
Old 09-01-2002, 12:37 PM
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Well finally my ABS light went on but went off. During cold starts, engine will run and then a 2nd time of cranking it will start fine. No hot start problems. I also have hesitation. Is their a definitive guide to changing the OVP on a 300E.
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  #5  
Old 09-01-2002, 01:49 PM
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The OVP relay is really just a fuse. It powers the systems involved. It is the ultimate in simplicity. If the system is functioning at all the OVP is obviously good.

The reason this isn't lightbulb clear is that KE systems work fine without electronic control. Cold starting is poor as cold enrichment is all electronic. Hesitations can be noticed as acceleration enrichment is electronically enhanced. There are more that one power leg of OVP which allows the combined symptom of ABS light. The ABS light comes on because the ABS control unit is not powered and turning the light off is one of the control units functions.

The way I test OVP is to monitor EHA current. No current probably no OVP. Any current, OVP is working.

The severe exception to this is the OVPs ability to act as a resistor to the control unit. I have caught OVP resistance causing a voltage drop (not complete shut-down) such that idle current (usually over 600ma) would drop to 350-450ma. This causes the idle valve to about totally shutdown the idle. Idle speed drops to 400rpm or so and dies. One of the common idle problems. This is a problem that won't happen with a good OVP or NO OVP. It can only happen when there is a voltage drop through the device.

Over the years the oVP has powered different systems and has many different syptoms. Only in the electronically controlled fuel systems does OVP become critical. An HFM system powered by OVP would be a sure nostart without OVP.
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  #6  
Old 09-01-2002, 03:50 PM
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Adding to SBs last line..

If one were to look at the power feed block diagram, you will see that the HFM ECU has to be powered up by the OVP, but once the engine is started , the OVP can actually be disconnected as
power is now supplied to ECU from engine supply [alt circuit]
So, unplugging an OVP with eng running is not a good test for OVP as the engine will still run w/o OVP.., but it will not start w/o OVP...
Thats why the common "No Start" OVP symtom and the little Tap-Tap relay trick...

..or there abouts..
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  #7  
Old 09-02-2002, 05:52 PM
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Well, I actually removed the OVP (just to see what would happen) and the car started and ran fine. Car is a 4 cyl E220 16V with HFM.

ABS light will always come on if OVP is bad.
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'08 Chrysler 300CRD (MB OM 642 engine)
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  #8  
Old 09-02-2002, 06:12 PM
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Wonder if UK wiring is different..or possibly a different relay

US version HFM require OVP start-up [ just verified that on an E320.]
Have no access to E220 schematics here and Fast Lane does not list OVP on the Euro section, so don't know if they use same part.
Would you have the part # on yours, by chance?
Tnx
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  #9  
Old 09-02-2002, 06:25 PM
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Arthur,

I think he is talking about a 89 4cyl. I should be KE.
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  #10  
Old 09-02-2002, 06:35 PM
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Quote:
Originally posted by stevebfl
Arthur,

I think he is talking about a 89 4cyl. I should be KE.
SB
That is the orig poster..[KE]
The Mick J post is the one we are referring to --he has a 95 Euro e220 and I have no info on the OVP circuit on UK
models [ He is in Surry, UK]
He states that the OVP feed is ABS and not related to fuel/ign as US versions are ,,, so that is where the starting OVP diagnoses on HFM is coming from.
You may have some info on if there is a difference here/there on this set-up.
All my info is US based and shows/states OVP feeds HFM-SFI modules..
Thanks.
Arthur
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  #11  
Old 09-02-2002, 07:20 PM
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I do have european info, but not at home.
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Continental Imports
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33 years MB technician
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  #12  
Old 09-04-2002, 01:06 PM
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Posts: 104
OVP replacement part number

Ok, I have decided to change the OVP. The relay looks old,
probably a factory one.
The part number on top of it is 201-540-32-45 What is the replacement part number?
__________________
1989 230E, 8v, 166.000 km, updated to 94/95 trunk & hood
2002 Daewoo Nexia 50.000 km
Sold:
1987 VW Jetta GLE 16V, Recaro seats
1982 Volvo 240 DL (lovely car!)
and few more american cars.
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  #13  
Old 09-04-2002, 04:22 PM
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Join Date: Apr 2002
Location: Surrey, Uk
Posts: 254
My car is a 96 model (built November 95) E220 estate. It has the same 16V M111 engine as C class. It was never sold in the US (who would want a 4 cylinder engine when your petrol is so cheap!)

The OVP part No is 000 540 67 45. There is another much smaller relay nearby with a fuse on top part No 000 542 96 19. Engine doesn't start or run without this one.

(the 89 230TE was written off in an accident)
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'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)
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  #14  
Old 10-14-2002, 04:57 AM
C Paul
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I have the same hot start problem on my 1991 uk spec 230e. I have a problem locating this ovp as there are a number of relays behind the battery.

Could you post a picture of it or describe its size height width etc to assist.

It would be helpful if the experienced merc mechanic could check his european spec sheets to see what it refers to.
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  #15  
Old 10-15-2002, 03:38 PM
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Quote:
Originally posted by stevebfl
If the system is functioning at all the OVP is obviously good.

The way I test OVP is to monitor EHA current. No current probably no OVP. Any current, OVP is working.

The severe exception to this is the OVPs ability to act as a resistor to the control unit. I have caught OVP resistance causing a voltage drop (not complete shut-down) such that idle current (usually over 600ma) would drop to 350-450ma. This causes the idle valve to about totally shutdown the idle. Idle speed drops to 400rpm or so and dies. One of the common idle problems. This is a problem that won't happen with a good OVP or NO OVP. It can only happen when there is a voltage drop through the device.

When my car starts it's rough idle/stall condition, I can remove the OVP fuse and it works ok in limp. Does this sound like a bad OVP or just throwing the rest of the system into open loop?
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