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Testing OVP relay function.; Car difficult to start when cold
Topic Started: Sun Oct 22, 2006 9:31 pm (4,133 Views)
190man
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Hi guys!

How do i test the OVP relay is functioning correctly on my 2.6?

I dont even know where it is? Can someone post a pic of its whereabouts in the engine bay?

The car is difficult to start when its cold. Itll turn over for about 10 seconds and will then struggle into life, Sometimes itll die. Itll do this if left for about 2 hours too. It fires up straight away on occasions other than mentioned.

Once the engine fires it runs perfectly on all cylinders. It will perform these symptoms in dry or wet weather regardless and all the ignition components are in good nick and dry.

My ABS light is on too, occasionally goes off for a few seconds while travelling but is more or less on all the time.

Not sure if the engine is running rich. Is this a fault to do with the OVP?

Somebody help me out here!
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mike65
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Check this thread

http://community.190revolution.net/mainten...light=OVP+diode

Mike.
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pentoman
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Resident OVP Expert
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190man
Oct 22 2006, 08:31 PM
Hi guys!

How do i test the OVP relay is functioning correctly on my 2.6?

I dont even know where it is? Can someone post a pic of its whereabouts in the engine bay?

The car is difficult to start when its cold. Itll turn over for about 10 seconds and will then struggle into life, Sometimes itll die. Itll do this if left for about 2 hours too. It fires up straight away on occasions other than mentioned.

Once the engine fires it runs perfectly on all cylinders. It will perform these symptoms in dry or wet weather regardless and all the ignition components are in good nick and dry.

My ABS light is on too, occasionally goes off for a few seconds while travelling but is more or less on all the time.

Not sure if the engine is running rich. Is this a fault to do with the OVP?

Somebody help me out here!

Good description of your problem!

Your ABS is powered by the OVP, so almost certainly the OVP is the problem. I have seen the same problems a few times, and had it on my 2.5-16.

Unfortunately testing seems to be sketchy. The way the fail seems to be intermittent (hence your ABS light coming on and off).
I took apart and tested, in every way I could come up with, the OVP from my 2.5-16 (as I had pretty much traced my starting and ASD problems there), and I could not find anything wrong with it.

However I bypassed the bit that I knew was a problem and instantly everything was better (can't remember how I did it).

Anyway, I then knew the OVP was the problem and replaced it. Since then my ASD has been faultless. The same can't be said for the starting, but that's not a big surprise with a 16v, although it is greatly improved!

You could check it's inserted properly when you figure out where it is (a tall box next to the battery).
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190man
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Ok great! Thanks for your response

Ive started a thread about this in the Electrics section.

Im going to go and buy one from my Merc dealer and change it over. Hopefully this will solve the problem.

Roughly how much are they to buy and does anyone know the part number for it. Mine is the 2.6.
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cossie connoisseur
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there can be only one ;-)
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They are about £80- not cheap
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Conrad
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Therapy Needed
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My 2.5-16 one was £55 + VAT brand new a couple of weeks ago from the stealer.
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cossie connoisseur
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there can be only one ;-)
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Cool B) still a crap price
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Conrad
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Therapy Needed
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Yup. :(
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190man
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Ive changed the fuel filter and i filled the tank with Shell V-power the other day.

I only put V-power in to try it out as my local is only charging 87.9 for it!

Anyway car is starting first time when cold! a drastic improvement. Im thinking its prob the new fuel filter that has solved it more than just the V-power.

By the way i havent noticed any significant performance increase with this fuel even if i adjust the ECM advance dial in the engine bay.

I am getting worse fuel economy however. I havent finished the tank yet so ill let you know how i do. Last tank of regular unleaded gave me 320miles on what i would describe as an 'extra urban' cycle. I think it equates to around 31 mpg
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Cossie 2.5
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mike65
Oct 22 2006, 08:51 PM

Hiya... I've just done this test and it gave me a reading of 775!?!?!?!? :blink: :blink: What the hell does that mean... What reading did anyone else get??
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pentoman
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Resident OVP Expert
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Have you replaced the OVP?

It sounds like it definitely is not working.
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Cossie 2.5
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I haven't replaced it... do you know what this reading represents??
I dont have any of the bad starting type problems that people talk about when the OVP is faulty....??
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pentoman
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Cossie 2.5
Mar 5 2007, 01:42 PM
I haven't replaced it... do you know what this reading represents??
I dont have any of the bad starting type problems that people talk about when the OVP is faulty....??

Sorry got confused... I was talking to the original poster not you!
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GEZIJ
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Cossie 2.5
Mar 4 2007, 11:19 PM



Hiya... I've just done this test and it gave me a reading of 775!?!?!?!? :blink: :blink: What the hell does that mean... What reading did anyone else get?? [/QUOTE]
yeah, i got a similar reading when i checked mine.
think its the resistance value.
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Cossie 2.5
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GEZIJ
Mar 6 2007, 06:14 PM
Cossie 2.5,Mar 4 2007
11:19 PM



Hiya... I've just done this test and it gave me a reading of 775!?!?!?!? :blink: :blink: What the hell does that mean... What reading did anyone else get??

yeah, i got a similar reading when i checked mine.
think its the resistance value. [/QUOTE]
OK cool... so does that mean that it's working!???? If you got a similar reading and it's working then I shouldn't need to replace it???!? :wacko: :wacko: :blink:

So what is this guy talking about with his reading?? http://community.190revolution.net/mainten...light=OVP+diode


Confusion!?!?!?!?!?
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cossie connoisseur
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there can be only one ;-)
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Link not working :)

Just cos on reading is wight does not mean its all working hunky doory ;)
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Cossie 2.5
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cossie connoisseur
Mar 7 2007, 09:16 AM
Link not working :)

Just cos on reading is wight does not mean its all working hunky doory ;)

Mike 65 on the Rev states this...

1. Remove OVP relay
2. Use approved multimeter. Set to diode testing
3. connect (+) testing probe to terminal 31
4. connect (-) testing probe to terminal 30
5. nominal value is 0.4V to 1.5V
6. if nominal value is not attained, check 10A fuse or replace OVP


That is how to check the OVP... so what the hell does 775 ohms mean!!???
I am reluctant to replace it just for the sake of it if it does work though and apparently this is the way to test it!??
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cossie connoisseur
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there can be only one ;-)
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Firstly why are getting a reading for resistance and not voltage :)
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Cossie 2.5
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cossie connoisseur
Mar 7 2007, 09:34 AM
Firstly why are getting a reading for resistance and not voltage :)

That's a damn good question!! I actually wrote ohms incorrectly! The meter was set to Diode but gave the reading 775... I'm no expert (clearly!) so what does that mean... it certainly isn't 0.4V-1.5V from what I can see!!
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cossie connoisseur
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there can be only one ;-)
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You need to measure the voltage but as you seem to have not to much experiece with the component take it to mercedes and they can quickly check it for free ;)
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Cossie 2.5
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cossie connoisseur
Mar 7 2007, 11:53 AM
You need to measure the voltage but as you seem to have not to much experiece with the component take it to mercedes and they can quickly check it for free ;)

Difficult to get the car to the dealership with no OVP relay in at all :driver: dazzle.gif dunno.gif
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