At the end of my tether with OVP circuit!

[Joloke]

I have been having problems with my OVP circuit on my 89 w124 230e and I have just about reached my limit and hear is being removed from my scalp in a timely manner!

When I first got the car being so excited I never noticed that the only dashboard lights on start up were parking brake and ABS

My garage wrongly diagnosed an alternator (well its wasn't charging so I see their point)

I could of got angry but in all fairness the original alternator bearing was a tad vocal

So armed with new alternator nothing had changed

Then the battery which was old was diagnosed as having a bad cell,fair enough it did as the no charge state had finished off the old battery:fail

I started reading up and asking advice to be told it would be the OVP,I bought a new OEM one at £70 Ouch......

I delivered it to my garage to fit only to be told we knocked the old one and it started working

They suggested I see what happened and keep the brand new one in the car and should it fail again just swap them over

The old one worked faultlessly for 7 weeks,then...................................................

:fail

So I swapped them over but still a big fat fail!

So I read how to test them out of Situ on a bench,this I did and no surprise the brand new one worked perfectly,as did the old one

So after that I found wiggling the wires to the socket or re seating the relay it would work again:bannana:

Sometimes for an hour,a day,a week

I figured it must be the socket as everybody told me they are stiff to get in and out and mine wasn't.

So yesterday I cleaned all the socket pins with emery paper as did the relay pins. I opened the bottom of the socket and photographed the wire colours and positions before removing each pin one by one and as expected they were spread open and loose so with needle nose pliers I squeezed them all gently back to former tight operation

Pushed the relay back home now nice and tight with good contact and nothing!!!

It does click on/off in situ so at least I know the switched and ground must be good?

I am at the end of my tether now

I am going to try and re flow the solder joints on the socket pins,If that doesn't work I don't know where to go from there?

I did consider getting brand new Pins and Pin bushing from Mercedes parts and making a new harness from scratch and bypassing the Benz original if only I know where all the wires end up terminating?

Just want my car back on the road,its definitely an OVP issue without a doubt as wire wiggling etc get it up and running again sometimes but as they are all bunch together I cant say which one?

Helppppp!!!!!

 

[optimusprime]

At any time has anyone opened up the ECU computer. Its in the same place as your ovp relay .On the top it as this large metal clasp to hold the top on. Inside , it will have lots of contacts .If its been opened it is easy to re fit it , and a couple of pins, can be out of line bending them in doing so. Some will not make contact from time to time. Only a guess. Be very careful putting the lid back on as a part of it as to lock in the bottom half before you clamp it back up again .

 

[optimusprime]

Jolo open your fuse box up .Remove every fuse one at a time and inspect them . If you have a fuse that sometime is making a contact can be the problem if it ran for so long before stopping. I would check them. All items are managed by the ovp and if the circuit as no power it wont activate it .The same goes for earth points.

 

[Joloke]

If all else fails its an Auto Electrician but you may be onto something here?

I do wonder if the OVP Directly connected to any of the fuses in the fuse box and if so which one?

I have just looked in my fuse box and previously I thought they all looked fine until you look again

Some of the copper contacts are black some have green oosing out of them

The other thing I have noticed is some of the fuses are lower amperage than the handbook says should be in that position

But my car does not have some of the accessories that are listed so are they being used for an alternative use?

I am going to replace all my fuses and clean the contacts but need to locate some copper fuses first

It the meantime I thought i would clean up my existing fuses but discovered some are warped and the one for my electric roof has no continuity as the center of its contact point has worn through to the plastic

Strangely enough the roof still works

I don have pics but cant upload them right now

BTW There are two fuses that are smaller value than what my Handbook states?

I don't have some of the options though so it might be right? I have no way of knowing?

 

[Joloke]

Just out of interest what Colour/values are the fuses "D" and "E" in your fuse box as mine dont match what it says in the owners manual!

That said my car doesn't have the features for those fuses

Does your car have an auxiliary fan (fuse D) or Electrically operated seats and steering column (fuse E)?

Fuse D 16amp (mine has 8 amp )

Fuse E 25amp (mine has 16amp )

 

[Joloke]

Here is my fuse box and fuses as they are right now

And the handbook that differs in opinion to Fuses D and E Book says on this the fuse box has different fuses in there

Going to clean up the contacts and tighten the screws underneath and source some proper brass/copper fuses While I am doing that though ill replace them for new aluminum fuses short term rather than leave the one in there in as they appear to be in poor condition

Nothing ventured nothing gained and at least its something else to tick off the list

 

[optimusprime]

Fuses you will get from Sheridan Marine. I looked on ebay for ages .Even purchased some that i understood to be copper or brass .That were alloy after all ,and the same as i wanted to replace . As for the location of fuses , as long as there is a fuse in the locations i can see in your picture it will be ok .If the item is not in the car it will have no fuse for it.Mine as E missing and F .and one 8 amp on row of my head i think it was 11.

 

[Joloke]

Makes you wonder why mine has fuses D and E then?

mine had car phone in the past maybe they have used to empty fuse contacts?

Might try it without those when it all goes back together

Just looked at Sheridan Marine even they look to sell Ally ones

Its all very confusing

I know what you mean there are some which look to be brass but I think may be plated aluminum

Looking at the pics is mine a fuse box you think would benefit from a clean?