Mercedes Ke-Jetronic - The OVP, the Overload Voltage Protection Relay

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What am I talking about?
My topic is the KE-Jetronic injection system which I try to demystify as much as I can.
For all of you to understand the system in brief - Developed in 1973 and being mounted into cars up to 1993 as it went in history. But why these to letters!?(KE) K(from German "kontinuierlich" meaning continuos, without interruption) the MECHANICAL injection system on which the fuel starts flowing from the fuel tank sucked by the FUEL PUMP and delivered to the FUEL DISTRIBUTOR which sends fuel to the INJECTORS while the majority of it flows through the FUEL PRESSURE REGULATOR through its return line back to the fuel tank again. The letter E(electronic) has to mark the electronic sensors (the developement starting from early eighties) which had to inform the ECU about the current state of the engine so that the ECU(Electronic Control Unit) then could create current signal in mAmp(miliampers) and send it to four crucial components for the system - the EHA(the electro-hydraulic actuator,a unit consisting of a magnet, an electromagnet and a baffle plate) which had to fine tune the engine in each of its phases, the ICV(the idle control valve), the unit which was predicted for the engines perfect idle, the X11(the diagnostic socket) where the duty cycle(the ideal mixture) was adjusted and the X11/4(the code reader) - the socket which from any codes were read if present using an OBD1 scanner.
An extraordinary injection system which could be fully repaired in your own garage using a multimeter and a pressure gauge only for its fine tuning, together with some common tools.
"Happy Mercedesing"

[@sKraat528]

This guy is the Bob Ross of Mercedes Troubleshooting and maintenance.

[@mercedeske]

Thanks a lot, my friend! If we do something, let's do it in the spirit of Mercedes slogan - THE BEST OR NOTHING! The same thing I am trying to do with these videos!

[@sadeemsadeem9301]

Thank you very much For your method of Teaching... Nabeel from Baghdad.

[@mercedeske]

My pleasure. Greetings from Knjaževac, Serbia

[@peterarvaszulu5069]

Congratulations ! I didn't know you are from Serbia republic,and am proud of you. I follow you tutorials every day.Am writing from Zambia

[@mercedeske]

Thanks a lot for everything. Best regards from me. Happy Mercedesing 😃

[@phatboyevapes3824]

Hello! Thanks for the shoutout ❤️ -Nicole

[@mercedeske]

Hello, Nicole. It was my pleasure. Happy Mercedesing 😃 😊 🍀🍀🍀

[@r3FMusic]

Thanks..

[@mercedeske]

Always. Yours has 6 contacts for sure. They are simple made and that's how it's supposed to be 👌🏻

[@ronanconnolly2196]

Hi, can you please advise if its possible to buy replacement Bosch advance vacuum units for W124? I'm having difficulty trying to locate one. Thanks

[@r3FMusic]

@@ronanconnolly2196 what is the part number?

[@louis-vz9os]

Thanks for all your videos. It helps a lot in understanding how the KE-jetronic system works. Regarding the OVP, can I use 9-contact one to replace 7-contact one? Because 7-contact one is no longer available.

[@mercedeske]

I wouldn't say so. They are not connected the same way. The 7-contact one has one fuse(I have the one in my car) and the 9-contact one has 2 fuses. They are not connected the same way I believe. Did you search on ebay?

[@louis-vz9os]

@@mercedeske Thx for your reply. Only a few used available on eBay. Not sure about quality though.

[@Wnemer]

Hello, I have w201 2.0 1992 in Excellent condition, i wanted to do some maintenance but the car become worse : following have been replaced 1- new ICV 2- new EHA 3- new bocsh fuel pressure regulator 4-new bosch fuel pressure accumulator 5-new bosch fuel pump ( with check valve) 6-new fuel pump filter third party 7-new OVP original 8- new Fuel pump relay original 9-new temperature sensor coolant 10- new temperature sensor for the clatch fan 11- new temperature sensor for AC fan 12-new Air temperature sensor (the small one attached to the Air filter 13- new distributor cap and rotor 14- new spark plug HD7C 15- NEW spark plug cables 16 new O2 SENSOR third party 17-exhaust is in good condition new middle silencer and muffler installed 18- new potintionmeter adjusted at 0.7 19- new intake manifold Casket 20 new bocsh fuel injector s How ever the car performance is bad, RPM sometimes stable at 800 RPM some times GO higher at 1300, engine is not happy sometimes it shakes on Ideal and sometimes good. Car always starts good from first try at cold or warm Before i change all above the car performance was excellent i did all above because of very small ideal issue i was facing , and i wanted to smoothens it More unfortunately the car now drives bad and no one around can tune it , i am located in UAE Can you share your email address so i send you more details also happy to support your channel.

[@mercedeske]

[e-mail]

[@JimmyTomes]

Hello thanks for all of your hard work! I am wondering if you have any way to power the relay out of the car to perform these tests? Connecting a voltmeter is going to be hard when its behind the battery and ECU! Thanks again :)

[@mercedeske]

You would have to remove the relay for this test. Anyways, if you have no voltage on your ICV then your OVP is gone bad(if the ABS light doesn't come on). The ECU goes in limp mode as well so your EHA will not be working.

[@cetindenizdemircan9148]

You might try to run battery voltage to the correct pin of the OVP with some banana plugs. There is a guide on the Internet, you'll find it easily.

[@hojjatzare2483]

Hello Master, I live in Iran. The wiring diagram of the injector system ke jettronik can not be found here. If you can send it to me, please.

[@mercedeske]

Hello. You need to tell me from which year is your car and the label on the airflow meter. Is it lm0001/mt0001 or lm0008/mt0008? Mt is on the fuel distributor, lm on the airflow meter.

[@mercedeske]

I will send you what I have but you must understand that there were 4 generations of KE and the diagrams are not all the same.

[@boinboinboiin]

Hello, master. This is huge fun of you and Mercedes from Japan. I have w126(1990)300SE (126024) The engine stops sometimes. No problem at start, but sometimes the engine stops when the engine is idling. Engine RPM is getting low, than stop. Especially when I using the air conditioner. Please teach me should I change the bop relay? Thank you, huge respect

[@boinboinboiin]

Should I change the ovp relay?

[@mercedeske]

こんにちは、ありがとうございます、光栄で! Concerning the car, if you have hard starts then you should check the OVP and the ABS light should be on on the dash. Here if I were you I would check the ICV the idle control valve. Do a simple test - select the first gear, or D if you drive automatic and hold the brake, the car must not stall. IF the car passes that test then turn the steering wheel from lock to lock both to the left as well as to the right while the car is in N(or in neutral on idle). If the car stalls then it's the idle control valve which you should remove and clean in diesel or with the carb cleaner. Tell me does this stalling happens while you downshift or as you stop at the traffic lights?

[@boinboinboiin]

Thank you very much master. I’ll do the test you told me. It happens at at the slope once, so it might be down shift

[@mercedeske]

@@boinboinboiin Yes, that can happen.

[@hanenkamm1979]

I have an 89’ W201 2.6 and mine does not have this overload relay. I do have a couple of electrical problems. 1. My cruise control hasn’t worked in over 10 years. I replaced the control box underneath the passenger side, floorboard, but nothing. 2. I also have a problem with my instrument panel lights, not coming on when I turn on the running/headlights. however when I engage the rear window child lock button and try to open/close one of the rear windows from the button on the rear door, all of my dash lights work, and even dim with the dimmer switch on the instrument cluster. These two problems have eluded me for many years. Any thoughts? Love your content.👍

[@mercedeske]

Try replacing the actuator for cruise control, maybe that's the issue. Concerning the issue with the lights, I don't know what to say.

[@JOHNVASSIL]

Are the 6 pins OVP for 1986 MB 300E still produced by Mercedes? I can’t find one to buy in the US

[@mercedeske]

Search on www.rockauto.com You should find the part there and they are located in the USA 🇺🇸 😉

[@JOHNVASSIL]

THEY ARE OUT OF STOCK AS WELL@@mercedeske

[@hojjatzare2483]

Master, I always follow your videos, but since I do not understand English, I do not feel very well. If you can become a brother, send me a video or photo of the ke jetronik system. Thank you.

[@Godofworistas]

hello master 😃 I had a problem with the cold start and the ABS It was on permanently for a long time I was looking to find out what the problem is and finally the security of the ovp relay was turned on I changed it and everything fell into place.

[@mercedeske]

Hello. Glad you solved the issue. Happy Mercedesing.

[@Godofworistas]

@@mercedeske I just have a question what exactly is elz and how does it help how it works?

[@mercedeske]

The EZL is the ignition module. It works the way notches on the flywheel determine the way the timing is going to be. After reaching 460 revolutions per minute the so called crankshaft position sensor reads the revolutions and sends them to the micro computerinside the EZL. The computer converts Hertzs(the oscillation per second) in revolutions per minute(RPM) and creates so called TD-signal or the RPM signal which then activates the ECU, the AC compressor, the X11, the RPM gauge on your dashboard, the fuel pump relay. There is nothing you can do to readjust the timing manually, everything is done by a computer with a help of the CPS(crankshaft position sensor). Here is my link to that video. kzbin.info/www/bejne/Z4a0m4tuaLhrn6M

[@Godofworistas]

@@mercedeske thank you very much😃🙏

[@sadeemsadeem9301]

Hello my friend.. My question about terminal 38. What terminal 38 for?

[@mercedeske]

Hello. There is no terminal 38. There is 30 - voltage supply from the battery, 31 - ground, 15 - ignition ON, 87E - one for the ABS, one for the ECU KE, 87L - voltage supply for the idle control valve and 30a - the communication between the ECU and the OVP when the car is both ON as well as OFF - if any CODES appear, the ECU stores them. That's it, no any other number! I supposed you read number 30 as 38. Best regards!

[@IutubRider]

Hello dear, congrats for your explanations and perfect english! I have a 1986 G class 200GE with M102 engine. As the car has never run smooth, i wanted to check any fault code through the diagnostic port. Unfortunatly, while the car was running and I was connecting the code reader, i made a mistake with the pins and suddenly the car stopped running. It starts well, but dies suddenly. It seems that fuel pump isn't running, but I can ear the sound when I first switch on the ACC. I anyway bought a new fuel pump relay, with no success. I checked also OVP relay, fuse is ok, it seems to be fine. Any idea? Have I fried the ECU? thank you very much !

[@mercedeske]

Hello and thanks. Maybe you damaged the ECU because you shouldn't have done it under voltage only when the engine is OFF! Remember that in the future! Try replacing the ECU for now.

[@IutubRider]

@@mercedeske thanks a lot for your reply! It is quite a rare car, i hope i will find an ecu :)

[@IutubRider]

@@mercedeske It seems I have fried the ignition control module, indeed the rev counter stopped working as soon as I made the error with the obd pins. No td signal, no fuel pump working. Is it possible? I will check and update you if you have pleasure :)

[@mercedeske]

@@IutubRider If you can't get the TD signal, then you should replace the EZL, the ignition module otherwise your ECU is dead, the fuel pump relay, the RPM gauge, the AC compressor.

[@IutubRider]

@@mercedeske yes, i will replace. it is strange because it is not completely broken (possible?) as if i shortcut the contacts on the fuel pump relay, the car stays on

[@mb.warehouse_find4221]

I have a 1982 230TE

[@mercedeske]

What troubles you?

[@monsieur420]

Is the ovp supposed to rattle when shaking it with my hand?

[@mercedeske]

If it rattles something is broken. So - test the contacts on it - 30(power supply from the battery) 31(battery ground), 15(ignition on), 87e(power supply for the ECU), 87L(power supply for the idle control valve), 30a(the connection between the ECU connector pin 15 and the OVP). If you get beeping sound on all of them, then your OVP is okay.

[@Aboood107]

Plz help ! my car stall after start few minutes and hard start , in high speed sometimes drops the rpm when deacclrate stalls

[@mercedeske]

At first replace and calibrate the potentiometer, replace the injectors, check the coolant temperature sensor, replace the O2 sensor if you have it, if you have hard warm starts replace the fuel accumulator. That should make things better for now.

[@tikavoyan2215]

Hi sir , I cannot startig my w124 E 2.6 , can you help mi how can I fix , THANKS .

[@mercedeske]

That's too wide. Start with the ignition, vacuum leaks, mechanical part of the system and end up with the sensors. It's simple - just take measurements and compare them to the nominal values. As I have not the measurements from your car, nor any service history, I can't be of some help You must tell me what you have replaced, how many km you have on the clock, from which year is your car. Without these data I can't tell you practically anything!

[@tikavoyan2215]

@@mercedeske thank you very very much BRO

[@monsieur420]

So we can use the 9 contact ovp on a 7 oem ovp