Mercedes OVP relay repair

How to resolder a faulty Mercedes OVP relay (overvoltage protection relay) this relay can cause problems with idle speed,ABS brakes etc. ..jump starting another car or improperly hooking up booster cables can also cause the relay to become fried,as can moisture/corrosion. follow me on twitter / fupabox

[@JimNoro]

You bailed me out big time, my 87 300D needed one for awhile! this fixed it right up and the car runs as it should. Thank You!!

[@fupabox]

Great to hear!

[@ParFektion]

Thank you very much for this video my friend! You just saved me $115! ☺ My ABS-light sometimes started to shine at the same time as the speedometer dropped to zero. With your fix everything now works perfectly! Thank you very much kind sir!

[@fupabox]

+Angus MacGyver glad it helped :)

[@stevebrimelow]

My (W124 230E 1992) was shutting down while driving, so first I re-tinned the OVP as per your guide, but the problem remained. I then re-tinned the fuel pump relay and this solved the problem. Thanks for your informative guide.

[@stevebrimelow]

***** One question though, since I did the re-tinning, I'm now having an issue where the central locking doesn't open when I switch off the engine. Could this be OVP related? Should I maybe just buy a new one?

[@fupabox]

***** There are a few things I would try..1) try pulling and hold the drivers door unlock knob or switch on the dashboard for 10 seconds while shutting the car off ..not sure if your w124 had the dash button.. 2) if you have the 2 button remote ,press and hold both while inside the car..but I think your w124 had a single button. ,,if it has the single button, lock the car with the key, unlock with the button and continue holding button for 10 seconds 3) unhook the negative battery cable for 1/2 hour and hope it resets . 4) unlock the drivers door with the key and keep it turned in the unlock position for 10 seconds... 5) The fuel pump relay would be activated by the ignition, so thinking backwards, when the key is turned off the power to the fuel pump relay would be cut, and send a signal to unlock the doors (not quite sure if that is how it works, just assuming ) if so maybe the pump relay still has a bad connection. 6) hope it relearns to open on it's own

[@LeonW124]

Thank you very much for this video, I re-solder my own OVP for a Mercedes w124 E 200 D and works out. Very useful, very nice job explain everything and share with as.

[@lpi6608]

my ovp started acting up after I left my headlight on and had to boost the mb.. Like everthing else that needs repaired before replacing. I googled it, followed this youtube ..resoldered everything did a pretest perfect..it works .. many thanks Fupabox

[@fupabox]

very welcome...glad it helped

[@rogersciberras1253]

Thanks man. just saved 100euro. my 124 abs light was coming on and tacho not working. so i hit the ovp with a srewdriver and light went off and tacho worked. so i soldered it as video says (20min job) and now its perfect. thanks and keep it up man.

[@fupabox]

excellent.. glad it helped

[@giusemancuso]

thank you i resolder mine ovp and now work as new , ther was a circular crack in a couple of solder barely visible

[@TheTaz069]

I for one want to say thanks a ton!! Have to make a mention to ya thou I did have your vids stickied in club 202 just for the sheer persistance in working on these mercs. And I keep coming back for more info. Thanks again for all the time you spend and keep up the great vids. You help bring much simpler answers to some complicated questions for some. Sorry club 202 is a mercedes club as we all deal with older cars and alot of your topics cover some of the most needed things

[@thomasrose6962]

just wanted to add that tapping the OVP with a screwdriver or something while the engine is trying to start or while running and getting some response is a 100% positive sign that the solder connections have come loose

[@fupabox]

+Thomas Rose Good info

[@SWF1127]

I would appear that the addition of the new coil FINALLY did the trick on my '87 300E. It was a little slow to gain a steady idle and died a few times as before but in four or five minutes came to life. Of course the new fuse in the OVP didn't hurt the effort either... Most grateful for the help here on Y/T and "fupabox's" seamless input....Next up swapping out a tank...No particular expertise for this chore either....:-)

[@fupabox]

prob took a while to clear the un burned fuel in the intake and unfoul the plugs...never had to replace a fuel tank, but I'm pretty sure it comes out from the trunk.. I may have something saved in my bookmarks on it,,,yup..w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/103/47-4100.pdf

[@SWF1127]

***** But of course the "Benz Angel" would have something tucked away on fuel tanks. Little familiar but only as far as the &^%%$# sending units. I hate them and the in-car install... Hoping "out" easier....Your diagrams here will be most helpful once again...It's not here yet but cleaning and delousing re-prepping for install will be first chore..Been assembling new parts like fuel strainer, sending unit, new vents etc..Hoping to swap some of the old stuff over but we'll see what happens...Tks. again..

[@fupabox]

SWF1127 de-lousing.. lol

[@kristofthibaud8491]

what are the symptoms of a bad relay? i'm having trouble starting (cranks ok) my 95 c280. Thanks

[@xvidasx]

Unreal thanks for video I'm just fixt my w201 2.5 ABS light, one was cracked so one touch of solder fix it

[@TheFella1200]

Done worked for five minutes. So clean contacts as this could be enough to activate electro magnet that is hindered by poor power supply .

[@EnricoDePaoli]

Amazing video. Many many thanks. Will try this tomorrow no doubt. Do you know if other electrical bugs, like radio turning off by itself, instrument cluster sometimes not working, ceiling light only tuning on manyally and not when the door is open (only the rear ceiling light works fine)... alarm remote control... can these all be faulty due to the OVP relay? Many thanks again

[@fupabox]

yes . OVPs can cause all kinds of weirdness

[@EnricoDePaoli]

@@fupabox many many thanks for your help

[@alanOHALAN]

hi, the socket the pins go into, has two wires, do you know why two wires, because I broke the two wires off one of the socket, I think it is conecting to the #87 pin. The socket has too little remaining wires left, so how do I repair the socket?

[@jaeski33]

Was it replaced with something else?

[@jaeski33]

The one in front of the battery in the trunk is the fuel pump relay. The OVP isn't there on the 97 C280. Can't find it anywhere...

[@youngsil11]

Thanks for the reply. Would you know the positions of the relays in the K40 when energized and not. In an attempt to see if the relay defective, I observed the relay when energized and not. The relays are normally opened when not energized, and all but one (the 1st one from left with relay facing you) was closed when energized. The question is whether they should all be closed when energized. My w210 is idling very high, even with the ETA replaced (w/ a used one). Your comments is highly appreciated.

[@fupabox]

this is a great site for showing relay locations etc. lots of workshop stuff...just annoying pop up ads to x out workshop-manuals.com/mercedesbenz/

[@jakeweiman6157]

Best way to check an OVP relay on a 1990 300D? I'm having idle issues. It idles very low and almost stalls..

[@ChiefWiseEagle]

Jake Weiman same here have u figure out what the problem is

[@dinispaulino7512]

Same problem with my 1991 300D! Idles too low when it's cold, but when it warms up the idle is fine...

[@jaeski33]

It isn't located there either. The fuel pump relay is there and misc 15 AMP fuses. Could the C280 not have one for a 97'?

[@patrickduggan6363]

Great Video, thank you.

[@fupabox]

You are welcome!

[@youngsil11]

where is this relay on 1996 e320, w210 ?

[@fupabox]

w210 has no ovp... has a k40 relay...

[@grendizer5439]

Hi.. I have 96 E320 with no ground to the fule pump relay inside the K40, can you help please?? Thank you

[@fupabox]

Check inside the K20 relay box. it's simple to pop the top off. The likely cause is a bad solder joint since all the relays within the box use the same ground . I've repaired a few of them in 15 minutes by resoldering the contacts inside the box

[@ChiefWiseEagle]

My 1986 420SEL runs longer than 10sec or not idling erratically at times, I also have to hold my accelerator pedal down to keep it running even then it may die after holding it all the way down plugs and wires are new coil is new rotor is new cap is good full of oil and coolant fuel pump and filter are new timings in spec throttle plate cleaned fuel distributor is original but has ran tons of cleaners in fuel please help

[@fupabox]

Check to see if the egr valve is moving properly . It is a regular issue on the older Benz models. Also check all vacuum lines for leaking . You may need to remove the egr valve and clean out the tubes and also lube the crap out of the egr plunger so it moves freely up and down

[@createbad]

wow i never knew mercedes cant be jumped. So does this apply to the w210 models if so what do i do if my battery dies

[@1miltond]

I have a 190e 2.6 6 cylinder the car runs great but the start is really hard 15seconds to 20 or more is this OVP relay can be the cause of that? is this a symptom ? please if you have any info on this thanks

[@fupabox]

possibly... check spark plugs as well . does it only start poorly when cold ?

[@infinixhotnote3667]

Hi fupa, did u know where the ovp wire base connected to? Is it part of engine harness?

[@fupabox]

yes . it's part of the engine wiring

[@velocitygaming55]

If the ovp is bad will it blow the fule pump relay

[@fupabox]

yes

[@MrShutshot]

Do you know where it is located on a 1998 e300td?

[@447za]

Hi fupa! Could you help me a bit. I have m111 engine my w202 and idle is littlebit rough 800 - 1000 rpms, cold engine. I found in my engine compartment 1 vacuum line it was dropped on to my under engine cover its about 20cm long white vacuum line and i cant find where it belongs :/. Do you know where could I find vacuumline diagram.

[@fupabox]

that's one of the few diagrams I have never been able to find..It isn't in my factory manual either...check under the front plastic engine cover at the front/top of the engine..most of the vacuum lines go into there

[@Tellus671]

Hi fupabox, I have to ask you a question. I have a 94 c280 Mercedes with a IL6 engine(M104). The engine starts fine(cold or hot), but stalls without warning after a few minutes. I have replaced the fuel filter and the OVP(original mercedes part), but still no difference. Could it be the fuel pump relay or the CPS sensor, or anything else? Thanks a lot for any help from a subscriber in Norway

[@fupabox]

yes it could be either of those things you mentioned, it could also be an ignition coil, fuel pressure regulator, MAF sensor, vacuum leak... unfortunately it could be many things

[@thomasrose6962]

+Tellus671 if the insulation on any of the wires where they plug into any of the sensors is crumbling then the wire harness is original and MUST be replaced no matter how much someone may have tried to 'repair' it. any engine made from 93-95 has a defective engne compartment wiring harness.. even the 12 cyl and the diesels but only those years.. Under the cloth tape is where its really bad .even changing the spark plugs can abd will cause a poor running or even a no start. with no obvious reason. Your problem sounds like what they did when the harness was breaking down. There isnt much else that will cause that problem you have

[@lionofjudah4574]

Will this fix my non-working tach like I have read it might? Seems like a DIY I can handle...

[@fupabox]

+RogueTalent541 It's possible it will..bad OVPs cause all kinds of weird electrical issues.. all you need is a soldering iron (maybe a bit of extra solder) and 10 minutes... It may not solve your tach issue, but you won't have any problems doing it

[@robertgrimnes1]

Have you seen a video on replacing an alternator on a 1998 mercedes 500sl?

[@fupabox]

I haven't seen a video on it.. but pelican parts has a tech article with photos.. www.pelicanparts.com/techarticles/Mercedes-W129/09-ENGINE-Alternator_Removal/09-ENGINE-Alternator_Removal.htm

[@SWF1127]

Since the Fuel Kick-Down relay is a "kissin" cousin to the OVP-Relay located in the same neighborhood, thought I'd throw a question out there...It's sealed up as a tight as a drum, no fuse so how do you know it's still good? There is this nipple thingy on the top with an in view but indicative of what? Be nice if KAE would endorse a color code of some sort for those of us less inclined..(Green and Red maybe) Can ya test these things somehow? Oh and are there other brands avail in lieu of KAE? 2nd less than two year old KAE product possibly crapping out and no fuse in this one...Thoroughly perplexed here in SWF...(A bit more congenial than standard WTF ) TKU....

[@fupabox]

Hate to say it , but I have never had an issue with one ,and haven't really taken much of a look at it.. I know what you mean by the nipple on top..just not sure what it is meant for. wish I could be a bit more help.. I seem to remember a post somewhere on re-soldering them as well, but if it is sealed as you say...maybe if you have a spare one you could heat the glued end and pop it open for a look.

[@mohamedkhayat4323]

My Mercedes E250 Turbo Diesel ! I have a problem in an engine that does not respond in a high way after changing the speed except the third degree and idle engine replaced the speed to the second degree! And another problem ABS warning light ON???

[@tawfiqalalawi1378]

Is it normal that w 126 relay which is in the fuse box 30 amp relay that get very hot

[@luisbollosa2721]

Amigo,podrias escribir exactamente para que sirve ese aparato ,para poder traducir . gracias.

[@velocitygaming55]

I’ve changed the fule pump relay 3 times don’t know what it is

[@fupabox]

The pump itself may be poorly grounded or the OVP is toast

[@alexander70356]

Hi i have a mercedes 1990 5sp w124 300CE-24. It runs fine starts fine but i have a few problems the gear shifting is really hard and there is no power. When you accelerate it lags then slowly gets to 40km. I am trying to solve the problem my self until a mechanic can look at it. any suggestions?

[@fupabox]

It could be engine related ,but it sounds more like a bad bearing or bushing in the transmission...or low fluid.....will it rev freely in neutral?...

[@rfbu]

great vid. however, I would prefer to test the device to confirm before tearing it apart. any circuit diagram by chance?

[@fupabox]

one printed on the side of the OVP itself

[@rfbu]

absolutely right, thx!

[@benzox9492]

Hey it works it was the relay all along I checked my pressure and everything the ovp came in the mail and I just poped it in but I found out jump starts can fry it no wonder why it was doing that but I have a ovp for sale that needs repairs lol

[@fupabox]

glad to hear it's all sorted out..good work :)

[@nehuge]

For those of you out there that see this comment, I posted a long video on how to remove the W124 dash and how to replace the vacuum actuator pods for the climate control. kzbin.info/www/bejne/ZoS4Z3Z8l5WKbdU Just trying to spread the word. Note that there are only 2 PN's left of the 6 PN's that are available from Mercedes or aftermarket. On the dual diaphgram pods you can buy one of the two pods that are available, remove their arms (white plastic just snaps it on), and you can take off the old arm from the old pod and transfer it to the new pod. NOTE: This trick only works on the dual diaphgram pods. Last resort you can get just the rubber diaphgram inside the pod that you can replace at a place called Performance Analysis in Tennessee, although you can't order on their website. You have to call them. Their part numbers for the two different diaphgrams are 2010 and 2020. On the W124 and W126, you can use one of their diaphgrams on the "center" pod, which is a single diaphragm. They are inexpensive, not sure how long they will be in business from the conversation I had with them. . Get a bunch and store them the rest of your life!

[@SWF1127]

What came out was a KAE 3.301.300 . What I'm putting back in a "New" Evan-Fischer EVA29572044828 (OES a/m) 1 yr. warr. Relay Fuel pump 12 volts Stud type 10-prong male terminal. New KAE was too expensive and present day parts list is getting a little strong w/Head Gasket blown and tranny showing some "bang" in later gears. Very kind offer but think I'm ok...Teetering on the edge of very recent re-built M103 and tranny. Body/shell, F&R suspension all German fresh in mine and just too good to simply let her go at 242K. Enuf new/near new parts top side to simply transfer over. That's the plan anyway..

[@edwardkurzius867]

Where is the OVP relay located I can't find it. I have a 1984 MB 500 sel

[@fupabox]

yours should be inside the fusebox under the hood..the one with all the relays in it..it will have a fuse mounted into the top of it

[@jaeski33]

I can not find the OVP on my W202 97 C280?? Any thoughts as to the location? Its not on the passenger side control box...

[@rocknrollerite]

I think it’s in the fuse box on the front engine bay top left

[@christygochenour6156]

the windows, door locks ,turn signals, rear defrost,and sun roof quit working and trunk wont open. all this happened at the same time. help me

[@fupabox]

it sounds like the front or rear "SAM" signal acquisition module is bad..it could be a faulty OVP , but I don't think the faults would be that comprehensive. It wouldn't hurt to re solder the OVP for good measure. The rear SAM is more likely the fault, and can many times also be removed and resoldered..it is under the trunk liner near the battery.... A used one from a wrecking yard would be pretty inexpensive... A new one at a dealership, is very very pricey... also check relay "K" in the diagram in this link workshop-manuals.com/mercedesbenz/c_230_(202.023)/l4-2.3l_(111.974)/relays_and_modules/relays_and_modules_power_and_ground_distribution/power_distribution_relay/component_information/diagrams/assignment_of_relay_holder_i/

[@benzox9492]

Can it also cause the car to start on warm start for 5 to 10 seconds then die instantly ?

[@fupabox]

The ovp can cause all kinds of weird issues...sounds like you may have a fuel problem though...can you give me a bit more information .

[@ChiefWiseEagle]

Mine does the same thing it run longer than 10sec or not I also have to hold my accelerator pedal down to keep it running even then it may die after holding it all the way down plugs and wires are new coil is new rotor is new cap is good full of oil and coolant fuel pump and filter are new timings in spec throttle plate cleaned fuel distributor is original but has ran tons of cleaners in fuel please help

[@SWF1127]

Have a loaner in there now but purchased a new one and have every intention of trying to break into the siliconed sealed vault to see what's what......Benz guru seems to think it became fried with the demise of one of the fuel pumps...Just more fun 'n games here on Worry Avenue....

[@fupabox]

yeah I guess a dead pump would put a strain on it.. you would think the fuse would protect against that

[@SWF1127]

***** But I still can't find it unlike the OVP relay....I'm left with guess work.....Not sufficiently dialed in for this stanza at all...Meanwhile what's with the huge disparity of cost on these things as in 80%? A shame that someone in the U.S. isn't making these things and the OVP Relay too...

[@fupabox]

SWF1127 if you give me the part # I'll see if I have any extras kicking around...have you checked "rockauto" for prices on the relay ?

[@SWF1127]

***** To your point...Used to use R/A for a former beast of a Jeep and some Benz parts but started to see better deals at Auto Haus of Az. and Car Parts .com. Only use OEM and sometimes sneak a peek at AMAZON. A bit helter skelter but occasionally find something that leaves me scratching my head... Ex.: That coil (OES) $32.00. Here's an interesting little company you ought to take a peek at. eEuroparts.com [e-mail] Some great marketing ideas and solid odds and ends supplier...

[@fupabox]

SWF1127 Thanks I'll check those out.. I've had a few duds from rockauto..lol.. I have a Porsche Cayanne tailgate strut from when I ordered a Benz steering damper..?? not sure how that happened, but they said to keep it, and sent the proper one...Thanks

[@SWF1127]

Might be redundant but worth try I hope....'87 300E recently tuned it. Rolled out this morning, back no prob but a restart to change car position yielded a ten second run then a quit. Same over and over...Yup battery new 7/14. Getting fuel to fuel dist..checked. Wondering if it's one of your relays? Changed 'em both out about four years ago. Any clues? Thanks in advance....-j

[@fupabox]

could be the ignition coil or the crank position sensor..also spin all your fuses to be sure they are getting good contact

[@SWF1127]

***** Going out to do the fuses now replace a few of the older ones too. Pulled the OVP since last write and that was a "bitch." Going to change that fuse despite fact less than a few years old...Thanks for input. Appreciate it! Hate it when this thing just dies...

[@SWF1127]

SWF1127 Here's one to add your knowledge pool re: OVP and supporting 10A that came with....Put the fuse on the meter at an Auto Zone and it came up defunct.....Two year life span and hoping the re-install is the answer...Of course jumping her earlier during a voltage meter challenge probably didn't help the cause much either......Meanwhile your coil suggestion is on order as that's got some years on it too... All help greatly appreciated and nice to see communities of this type still exist...-j

[@fupabox]

SWF1127 OOh.. good info... I wouldn't expect a 2 year old fuse to be toast, but they aren't made the same as they used to be... One of the things I always find myself guilty of ,is assuming "I just replaced that part so it can't be the problem" many times I have wasted time looking elsewhere when the culprit is right under my nose.. ..that, and "is there fuel in the tank" ... DOH!!! LOL..

[@SWF1127]

***** Sorry, KAE was the brand. Both the case of the OVP and environment behind the battery were clean and dry too. Since I'm Disabled and neither a tech nor a mechanic, I have to take these small victories with a smile. Getting the bloody thing outta there was a nice little workout too. Now, let's see if she starts...Gulp!

[@hossamabijomaaabijomaa4188]

Hi I already fix this relay at my home it's working good naw like new by the way the I was having a problem with ABS when I fix this relay the ABS Woking naw really and I have very good break naw thank you and my car starting quickly at morning naw

[@fupabox]

Good to know

[@altafraja6494]

Thank you so much

[@laboyga]

HELP :---)))) My turn signal relay is making a buzzing noise on my 1995 C280, so I think, I need to find a new one part #2018210147. Problem is a big black relay next to it we unclipped took out by mistake (Part # 2025420132). Now we can't get it back in. Can you help me or show me a quick video please :---))))))) What it contol? because everything seems to work :----))))))...........ASAP please

[@fupabox]

+laboyga the big black one is the lighting control relay... it has 2 big feet on one side at the bottom.. tilt those 2 feet so they are pointing down and then lower the other side into place.. you can't push it straight in.. the 2 long feet / legs go down in and lock under, then the other side presses in

[@laboyga]

+fupabox thank you. got it............What would i do with out your help :---))))))

[@fupabox]

laboyga excellent.. hope it all worked out :)

[@MrChiusaroli]

The OVP relay is a critically important device, and should be inspected and/or replaced at any signs of excessively fast idle speed, ABS light coming on for "no reason", etc. Don't repair it; replace it! They're inexpensive($30-50.00), and readily available. They do NOT retail for $100.00.

[@symbianfreak01]

OEM is 100 or more, cheap china crap are 30-50 on ebay and amazon

[@4630driver]

For an 87 300d, they're unavailable and used are $300 on eBay

[@waltwilliams1770]

Having to re-flow the solder joints suggests that these units have cold solder joints. This is a sign of poor quality circuit assembly. It could be that they were assembled with poor quality solder. It might be advantageous to extract as much of the old solder off with some solder wick and reapply new solder you know is good quality.

[@fupabox]

+Walt Williams That sounds like great advice

[@gorgonzo1a]

Ofcourse you can jumpstart a mercedes, jumped my w202 for instance about a year ago when i forgot the interior lighting on over night

[@BaronRosenhein]

Where's the part where you throw the fuse into the car and say everything works great again?

[@fupabox]

Lol..the car was in storage when this video was done...so it wasn't installed for a few weeks... I had removed the OVP relay before storing it so I could re-tin it over the winter... The cam position sensor ended up being the lumpy idle culprit

[@BaronRosenhein]

As I initially suspected :) Thanks for sharing.

[@mrstimerapillay8858]

Were is it R100

[@scottbiasi4006]

I am going to try this tomorrow on satans (last three of vin is 666) w124 wagon I’ve just about replaced everything and an ecu from a sedan

[@christygochenour6156]

1998 c280 sport

[@christygochenour6156]

Thank you very much for getting back to me so quick I'm gonna try that out today. Thank u again

[@benzox9492]

I made a video about it a while back here's the link kzbin.info/www/bejne/m5XXXqmCaLZqmtE pretty much when I do a cold start the car would work fine but as soon as it heats up and you turn it off and try to start when warm the car will start rough then it runs for about 5 to 10 second then it instantly does the on way to make it stay on I have to apply gas before it dies

[@fupabox]

it wouldn't hurt to try to re=solder the ovp..it won't cost anything and it is possible it is causing the problem..you can also do the idle re-set...when the car is warm turn the key to position 2 but don't start it...let it sit like that with the key on for a minute or 2...then push the throttle pedal about 1/ 2 way, hold for 2 seconds and release...leave the car for another 2 minutes ...turn the key off and then start the car and see if it helps...could be a dirty throttle body or MAF sensor on the way out as well...... 1 last question... what was the engine code that you had re-set, and does the car run ok after the stalling at warm start, or will it not idle at all when warm ?

[@benzox9492]

Yeah if I hold the gas for 10 seconds

[@mtbrasi369]

Where is it located on a 94 SL500

[@fupabox]

I believe it’s in the electrical box passenger side under hood near wiper

[@xalidmemmedov3778]

salam