Mercedes R107 500SL with electronically adjusted idle control valve. System overview, testing, troubleshooting and a cheap 50 cent fix of the Idle Control Module, FIX AND SAVE!!
You are my hero today, shop rate to look at my car was going to be $125 an hour. This 5 cent fuse fixe every problem my car was having, high idle, sluggish, no power, wouldn't shift right and the antilock light was on. The car drives like a dream, thank you so very much.
Dear Richard! Thank you for the video and I high appreciate your strong understanding of electronic parts. In past century we had never changed whole module of any electronic device, we hade repaired it for cheap money, as we had appropriate knowledge of what to measure, and how electronic work. Nowadays seems people lost this knowledge and workshops can just change whole modules or devices for huge money without going deep inside the problem, which can be sometimes fixed for 50 cents, as you've shown. Thank you very much!
Hello Richard, I want to thank you for your very helpful video. I fixed my 1987 Mercedes 420 SEL based on the information you provided. Perhaps my story will also help someone else. My car had been running very well for the past 6 months even though I had to park it outside in the driveway all during the cold, wet winter months. Two days ago I was driving to an appointment when several severe symptoms suddenly fear the worst. The wheels felt unbalanced, the power steering system squealed when I would make a turn, the Antilock Warning Light went on, and when I pulled over to try to figure out what was going wrong, the motor continued to idle a very high rpm. I could still drive it and managed to get it home. I then searched the internet and found people sharing their experiences that might solve the high idle rate by replacing the Idle Control Valve at an average cost of $1000 for the valve, not including labor. Then I found your video about the Over Voltage Protection Relay.... Even though I don't have a diesel engine and 420 SEL was not the model featured in your video, I looked under the hood and easily located the OVP Relay. It was difficult to pull out of the socket, and I had to pry open the clear plastic hinged cover over the fuse. I found that the plastic cover was not seated properly, the fuse was loose although not blown. I removed the plastic cover, cleaned the space under it, where two small cavities fit the electrical tabs that hold the fuse in place. I restored the plastic cover and reinserted the fuse so that all was right and tight. Then, reseated the OVP relay into it's socket and started the car. I was immediately gratified to see that the idle speed had returned to normal. There was a slight stutter in the engine, as if the fuel line had air in it....and I haven't taken it out on the road for a test drive at higher speeds.....but I believe all the above mentioned symptoms are gone. Bravo! Total cost $Zero. Lesson learned HUGE! Thank you Richard.
This is the reason why I post. Happy to hear you were able to solve it. The featured car is a petrol 500SL. The engine is very similar to yours. I will post more content soon!
Hi Richard. Thank you for putting this video together. You seem Very knowledgeable about how the ICM works. I have a 1984 380SL that’s idling rough. It starts right away. No issues there at all. Idles okay for 1-3 sec. Then the idle start to jump between 900-400. If driven it drives fine unless you come to a stop at a light etc. after about 5 minutes of driving, the idle start to rises to 1000 in gear and around 1800 in park or N. If I keep driving it longer it normalizes and the idle drops back to around 500. I did a vacuum leak test. No leaks. I changed the idle control valve. No change. I checked the overload relay. Seems okay. Fuse still good. I am running out of ideas and taking it to a shop is going to be $$$$$. I took the ICM out and opened it up. It looks a little different thank yours. So I am not sure which resistors I need to change. Is there a way to send you a pic of the one I have or Any suggestions?
Did you vacuum leak test both primary and secondary vacuum circuits? Sounds awfully a lot like vacuum leaks around the injector housing which is not noticeable as long as the car runs on choke. I have more videos on vacuum leak checks on my channel
Check the idle contact at the throttle butterfly for an idle contact grounding signal at idle . Check the female sleeves at the idle control box for tightness at the male pins . The air flow sensor position indicator , will cause a high idle when out of the 1 volt setting . You tube has a lot of stuff on that .
Richard, thank you for the video. I have both a high idle and the ABS light is on my 560slich which I just bought. I was so excited to learn about the fuse fix for the ABS. The fuse was blown. I replaced it and the ABS light went out but the high idle is still there. Looks like I have more testing to do. Thanks again. Stephen
thank you. your video enabled me to fix my control module (i replaced the 2 transistors cost $1.5). i'm in Sydney and the control unit is behind the dash/above the steering column (right hand drive). Also my module was at 10.5v (at Idle control valve and terminals 1 + 5 on control module board) with ignition on and motor running. idling at 1400-1500. Now at 4.5v 600RPM :) another point that may help others; the solder points on the control module board from connector to the board circuit were fractured and were not making a good contact, i needed to re-melt the solder around the connections. i assume that this was part of the reason for the failure of the transistors.
Happy to have been able to guide you through your cheap fix! I will be posting some more videos soon specifically how to adjust air/fuel ratio, how to replace convertible top, how to repair a cracked dash/seats and how to place new trunk carpet!. Subscribe and keep an eye out!
Hi Richard! Great Video! I was looking for some instruction for my W126 500SEL, but Your video is much better! since recently I am the owner of W126, 500 SEL, From the very moment of purchase, the engine were in vibration. were replaced power cables, all 8 pieces. After replacing the cables, the vibration is almost gone. Remained insignificant, but I sin on the nozzle, because after the engine plug, a sniff is heard, as if there is a pre-injection. I will take care of the nozzles at the next stage of repair. With the replacement of cables, a new problem has come up: on the cold engine, the rmp are around 650-700. As soon as the engine warms up, the rmp jumps to 1600-1700. I cleaned Idle Control Valve (000 141 14 25) - bucket of dirt. I checked the power on it (thanks to Your video): When ignition is on, Voltage is something around 14v , a working cold engine is 4.5v, hot working engine is 0.45v. When power is applied, I head a click in ICV. When the engine is cold and working, the RMP rise, when I disconnect ICV, when the engine is hot and working, I see no changes, while disconnecting ICV Proceeding from all this, I conclude that the ICV and Idle Speed Control Unit 0025454032 are in order. I go further. It began to measure the power supply on WUR (0438140) - the ignition switched on, the engine cold and running, the engine hot and running - the voltage 0. Here comes a question - what controls the power supply of the WUR? is it not the same Idle Speed Control Unit 0025454032? There is also an anomaly: Some times when the engine get hot, the RMPs are still okay (800-900). But it is maybe 5% of the cases
Dear Kenny, based on your research and conclusions I suspect two components. One is the idle controle model having a loose connection on a transistor and possibly the o2 sensor in the exhaust. The WUR is not controlled by an ecu but by a simple temp sensor however a lack of vacuum will show first on the WUR. Please check your dash econometer. Please look at all of the movies on my channel for more information.
Richard, thank You for reply idle controle model having a loose connection on a transistor - So I have to take apart a 0025454032 and check the transistors? Also I will check O2 sensor (Thank you for reminding!) dash econometer - in both cases (normal and high idle ) an arrow is on the left side.
Hi, your English sounds to me it has a Dutch accent, am I right? If so, I am also Dutch! Thanks so much for your instruction video!!! I also had the high idle rev problem suddenly in my 1982 R107 SL500. I managed to solder 3 new transistors and preventively soldered some new capacitators to the print of the "Leerlaufdrehzahlreglung"... And it works perfectly! It never ran so calmly when idle! I do now have a slight problem, that the engine stalls, when I restart, when the engine is still "half warm", but I solve this by pressing the gas pedal a little, to make the engine to start on a somewhat richer gas. When the engine is upmto working twmperture again, it runs smoothly. Of course I managed to save some money for a new idle rev unit, but the biggest kick I get, is from fixing it on such a fundamental level. Thanks again. And if you have any other tips & tricks, I' really interested. One funny fix I'd like to share is that I recently fixed my drfective dual car horns (left and right) by spraying WD40 on the connections as well in the horn unit itself... Like new! 😁
Hi Gerben, yes a fellow Dutchmen here. Glad to hear it helped you out. I would check the vacuumtubes when your car stalls. I have uploaded other vids. Otherwise your temp sensor may be faulty. Good luck
gerben kan jij mij niet helpen met mij probleem ik kan niet solderen heb al en hoop vernieuwd aan mijn 500 sl heb ook relais al vernieuwd die onder cash board zit
@@jonnysteenmeijer1831 Hi Johnny! Ik heb zelf ook hulp gehad met solderen van mijn gepensioneerde schoonvader, die electrotechnicus is. Dit was echter een "vriendendienst" en ik schat de kans niet groot in dat hij er echt werk van wil maken. Ik zal hem eens vragen, maar ik verwacht van niet. Desalniettemin, zou ik, als ik jou was, even zelf in de kennissenkring kijken of daar mensen bij zitten die nauwkeurig kunnen solderen. En dan nog even een tip: als je de transistors gaat vervangen op de printplaat, vervang dan ook (preventief) de elco's. Deze kunnen namelijk uitdrogen na zo'n lange tijd. Succes!
Richard, I suppose I should have mentioned that both of the ICM’s I tested put out 12.5v at the ICV connector when the the car wasn’t running and 17.5v when it was running. Any idea why they did that? In any case, I disconnected the ICV and took out the ICM, and the car now idles much better than it did with those things? How is that possible?
Great videos, Richard. Thank you. However, I was wondering if you’d clarify something for me. The MB manual for testing the voltage of the ICM when the car is running says to “Plug on coupling at idle speed adjuster in such a manner that voltage ca be measured on plug” However you measured the voltage in the plug when it was not on the ICV. Is there any reason why the voltage would be different when the plug is on the ICV? Also, as I just ordered several of the transistors you said go bad, can you tell me how you determined that they were bad? Thanks very much in advance 0:45
Yes because the leak voltage with the plug disconnected can still be 12.5v or whatever voltage the battery is. However when you put it under load the voltage will drop immediately due to consumption of power and the ICM not providing enough voltage and current beyond the “leak”. Testing both is essential because one will tell you that the OVP is ok. The other will tell you if the ICM is OK or not.
Transistors are bad when you disconnect the ICV and it shows 12,5v with the multimeter leads on it. If you connect to the ICV and drops immediately under 2-3V the transistors are bad. Either one or the other depends on the engine behind hot or cold. In any case considering the effort i would always replace both
Saved me a lot of needless troubleshooting, It turns out I did have 12v being supplied to ICV, and herd it click, so, guessing the air/fuel mixture on my 1985 380SL Once you cut the ring to separate the ICV, and cleaned, could you put it back together and use it? You had mentioned superglue, I’m just concerned with heat in that area. Thanks again !!.
Hi, glad I could help, also see my other vacuum related content and consider to subscribe as I will be uploading lots of interesting stuff soon. I have used superglue many times. Honestly the cap is a very tight fit and the superglue is only used to seal it off a little bit. Been using it for years without a problem.
@@horvath14041984 Richard, Where did you purchase the transistors?, I pulled mine apart, apparently it was a rebuilt unit as there was thin polymeric film covering the PCB
Hello, I have a problem with my Mercedes SL560 car. I checked the voltage with the ignition on... it was very strange, the voltage jumped from 0.01 to 3v, but it never gave a constant value. with the engine running, about 3.6v to 4.1v and it fluctuated. What do you think, will it be the controller or more the wires? Thank you very much for your help
Great video. I’ve got a 1985 380SL and around 60mph during the hot day (not at night) my cars acceleration starts to go in and out (never stalls). While the acceleration does this, I hear a clicking noise coming from the glove box. Could it be the Idle air control module? My cars idle also goes up and down when at idle with the AC on. I’ve also noticed that my cars gas tank isn’t ventilating properly bc a gallon of gas came out when I opened the gas cap. Could they be related? Could water and rusty cables be an issue? My car rides perfectly until on the highway. At first I thought the wind and gust were simply pushing my car back a little bit but I noticed it was accompanied by the clicking noise.
Hi Richard, thanks for all your very helpful videos, I wonder if you could help me, I have a 1983 r107 500sl which has a high idle speed, I have removed the idle control unit and found a burnt power transistor but unfortunately the number has been burnt off, can you tell me the part number or advise me where to find it so I can repair the unit,I also prefer to repair things like you Regards mike
Thank you! My 560SL 86' had give me high idle and abs light randomly twice, in the past three months. Now is fine, but I measured with the key on ignition (car engine off) the voltage in the power socket of the connector going to the idle valve, and it measures 3V (should be 12), It measures 4v with the engine running. I measure the voltage going to the socket of the OVP and it measures around 14v, I guess my OVP relay is the issue? How do you measure the voltage of the control unit if it's in place? not putting it all the way so you can touch the pins? thanks!
Ik heb precies hetzelfde probleem! Welk type transistors zijn het? Zoek die kleine zwarte ronde (warm+koud) en die grote vierkante waar je het over hebt. Dank!
Hallo Bob, weet ik niet uit mijn hoofd. Het staat erop als je ze los soldeert. Zijn vrijwel altijd op voorraad in meeste electronica winkels. Succes! Abonneer je voor meer video’s.
I bought this 3 transistors and will try to change them. I have unstable working of Idle control valve. Pls, can you tell, where is located temperature sensors which giving signal to idle control unit to change voltage on the valve? Which sensors responsible for the temperature readings from the engine?
Thanks Richard, good info. What about a surging idle? With the ICV plugged in, once I start the car, it runs ok for about 10 seconds before the idle starts surging. If I unplug the ICV, the idle goes to a steady 1400rpm. Following your checks shows 13.7V at the plug that goes on the ICV, not 4.5V or so that you had. The ICV clicks correctly with 12V applied. Any ideas? Cheers, Drew
Followed all of your steps. We bought a new voltage protector with a new fuse. We got 12 volts going into the new solenoid but no power coming out into the idle air modular. Do the resistors on the idle air control box stop the voltage from coming in?
The transistors keep the power from going from idle control module to idle controle valve. Have you measured voltage on idle controle valve in the pins and under load?
Yes we are only getting little voltage. .20 and we are getting that at many different parts where we should be getting 12 volts while key is on. And after it goes through the voltage relay protector. All our wires are good and have continuity. And we get a full 12 volts going into the voltage protector regulator but the problem is we are only getting .20 coming out.
Hi Richard, thanks for posting this video. Can you please tell me where the OVP Relay is located on a 1988 560SL I would like to test it (check fuse) before I order an idle control module. Thanks in advance
Hi Angelo, if its a LHD its in the passengers footwell to right on the A-pillar. also the fuses are located there with some relay`s. you need to loop up a bit and find the one with a fuse on top.
There are also a lot more steps to go through before ordering a new idle control module which can be expensive. is your ABS light on? - also i have a fix for that module for 50 cents.. check out my video`s
Yes thank you, I will go through the steps before replacing or trying to repair the Module. I will search out the fix you mention as well. Thank you again for response and for posting these video's
Hi again Richard, I replaced the fuse and the ABS light went off. The idle reduced from 1500 down to 1000 in park and down to about 600 in drive with brake on. Still seems a bit high though when in park and does not kick down. Any suggestions at this point ? Also, one other issue is that when accelerating hard it does not click down the transmission (passing gear as we refer to it) It does only occasionally on the highway. The car did do this when I first got it. I ruled out the obvious like the floor mat interfering with the accelerator. Thank you again.
I was looking for the two temp sensors on in the rear of engine and the other in the right side by the ABS, you mentioned in you video. I found the mounting holes for them but the sensors of cable were not there. How can I verify I have a true 560 SL engine? I love your videos by the way.
Hi Joe, the 560 should have both but I have seen with only 1. None is very unusual. These temp sensors are required for standard operation of the engine. You can check the engine number on the bell-housing. You can see it right side of the engine bay looking down on the bell housing. The number should start with M117
Where is the idle speed control? It varies on models but its not in my engine bay or under the passenger footwell. Ive looked under the steering column but i cant tell if what im looking at is the correct part
Hello, brilliant video, THANK YOU VERY MUCH. I have 82 500SEC which i believe shares the same engine as your SL, as everything looks exactly the same and even part on ICU is the same. I went through all the steps up to checking voltage on pins on Idle control unit. I have 13.7V between pins 1 - 2 at the top left and sometimes my idle goes up, when this happens i get 0 volts between botom pins 1 - 3 does this mean, that both my OVP relay and ICU went bad? Thank you very much for your answer
+Jan Novakovski when idle goes op and you check the voltage on the idle control valve not module. What is your readout? If high idle is at random you possibly have a bad solder point in either the OVP or idle control module. Do you have ABS?
+Jan Novakovski sorry did not read your post correctly If your idle goes op and shows 0 volt on the pins for the valve check the supply pins if you still measure the 13 volts there. You will eliminate either OVP or module. If supply is gone to then you need to resolder OVP points is supply is there you have bad soldering on your board. Check that and come back to me.
Thank you for your reply, yes i still get 13.7 volts on supply pins from OVP relay when my idle goes up. I already resoldered joints in OVP, no change. (i replaced blown fuse on OVP a week ago, maybe is alternator broken and supplying too much power? how do i check that?) Shouldnt there be a 12V on supply pins instead of 13.7V? Maybe thats why idle control module went bad. My ABS light goes ON at about 10mph and stays on. I think, that i need to replace resistors in idle control module, but should i replace OVP relay aswell as its supplying too much voltage to idle module? Thank you for your fast reply, Btw where are you from?
+Jan Novakovski you Can measure the OVP while engine is running, if you push the throttle the voltage should not fluctuate. Voltage should be 12v not higher then that. Cross check with voltage on battery leads. If elevate rpm is together with ABS you need to check ABS system. An ABS system fault can cause elevated RPM. A fault could be a bad wheel sensor. You can check resistance. Two on the wheel side and 1 under the rear bench. You can check the transistors without removing but if the problem is intermittent I tend to believe the problem is not in your module. It either fails or works all the time. It is an intricate system because it is connected throughout the car.
Hi. I have very similar issue wit my 380SL from 1985. Unfortunately I have not 12V on the idle speed valve. So I took apart the idle speed control unit and identified small burned place there. One resistance and one transistor look suspiciously as well. The unit is broken. Can you help me with its repair? Thank you so much for your very helpful videos to this issues.
I may be to far away from you. It is most likely the large mosfet on the side who is not getting the power to send to ICV ... OR! Your overvoltage relay is broken!! Quick check also see all of my videos
Thanks for the video, I have replaced idle control module and ovp relay, getting 4.2 volts at CUB at running temp and only .3 volts with only key on. Any suggestions?
Hello Richard, what size is the long brown resistor right near the pins 1 & 3.. Mine has blown and I can't find any info as to what size it's meant to be? Your help would be greatly appreciated.
Thanks video. I want to test it on the ground, but which of the premium leads should I give voltage? Mercedes W124 ECU 0 280 800 124 003 545 49 32 KE0004 12
Hi Richard. I am a happy new owner of a -88 560SL. The idle is between 2100 and 1500. My ABS lamp is on, so I checked the fuse as you mention in your great video. Unfortunately, it was not broken. I measured the plug to the idle control valve with ignition on and engine off, and it fluctuates between 0,3 and 2,4V approx, with an interval of 1 second. I connected the valve very shortly to 12V, and it clicked, as you explained in the video. Any suggestions? Great videos, I have learned a lot from those. Thanks :)
Does the abs light go on during driving or is t on when you turn on the ignition? If the latter also change your OVP or try resoldering the contacts inside
i have a 1984 500sel, the idle when cold is low but when it warms up it goes to 1500 rpm. disconnected the battery for a few days and the warm idle was fine for awhile but ended up at 1500 again
Hi Ervin- I do not provide the service to repair them it’s an easy fix anyone with some soldering skills could do. I am sorry. Perhaps a local hobbyist could support you.
Hi Richard! What a video! I have a W124 engine M103 year 1992. My idle is sometimes at 1000 rpm and sometimes at 500 rpm. In this car can I adjust the idle speed?
Hi Xavier thanks, please like and subscribe. I would check your O2 sensor. Intermittent high idle is usually due to running rich or lean. So check false air and fuel system and idle control. You have a valve as mentioned in my videos but it’s usually not intermittent. Good luck
You can check the clamp holding the MAF sensor. Sometimes it’s breaks or comes loose drawing false air and like I said checking your vacuum system is essential with these cars.
Hi Richard! Great video. I have high idle at 1500 with no abs light. I jump 12 volt to control valve and engine almost stalls. Checked voltage at connector and with key on only I have 1.5 volt. I am trying to bridge temp sensors but I have a different configuration than your model. Mine is a 89 560sl. The sensor at passenger rear of engine is a single pin sensor. I don't see another sensor on passenger front (low) not sure how to proceed without knowing how to by pass temp sensors. Do you have any info on this? Suggestions?
+Steve Chancey Hi Steve, 1,5v on the pins is too low. The valve is working when it almost stalls with 12v applied. I can tell you know that based on my experience I think your idle control module is bad. The one pin sensor has to be shorted to earth, engine block e.g.
Thanks for the quick response! I pulled my module out and it appears much different. How can I identify on my module the corresponding pins I need to check voltage on? Could I email you a photos? stevenchancey@rocketmail.com
I don't have power on my terminal 4. Putting a test light on to terminal 3 suddenly drops the rpms and the car shuts off. I have already replaced the overvoltage relay and idle control module on the 82, 380sl. What should I do next?
+Aras Mohammed OVP is against the A-pillar in the passenger footwell for a left head dash car. The module is behind the glovebox on a LHD car. You need to remove the glovebox insert with the plastic pins.
my idle control module box in my w126 500 keeps blowing a large black chip on it....I have to give extra earth to the idle control actuator on the engine to bring the idle down from 1500 to 800 rpm. my issue is high idle rpm 1200 to 1500 range each time ...
+Doc Ali I think you have a corroded or shorting wiring harness running from your idle control valve to your module. The wiring harness has a +12v wire in it that might short to the mass wire. That harness tends to become brittle due to excessive heat. Check the wires from front to back. I also recommend checking the copper of the wire. If it corroded it will have to much resistance. Last but not least check the draw from your valve and resistance if everything is in order.
+Doc Ali just another thing to check is the complete engine mass wire. A large metal litch wire strip. Or use jumper cables temporarily between the to just to check.
also my fuel pump won't start on turning the ignition switch on ...pump only starts on cranking ...replaced the kickdown switch relay but nothing happened
+Doc Ali this is normal, fuel pump for those Mercedes will never turn on on ignition only crank. It will also make a whining noise which is typical for that era. No need to worry that's fine
I missed your comment to check the diodes for identification as they were removed .I now have three diodes removed , I have replacements but I have no idea which one goes where on the circuit boardthe Diodes are marked 307B ,337/25 , 327/16 , do these numbers correspond with the diodes that you replaced , if so can you advise where each one is located on the board .Ian
Hey guys does anybody know why the idle speed when I'm driving goes way up and drops down and if it goes up it stays up for quite some time before it drops down please I need some help thanks
