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I did ME9.7 repair few time, if there are problem with CEL on and error code related to (P0030, P0050, P064D, P064E, 1337, P2237, P0607) then problem likely due to capacitor in side ME9.7 circuit pack, capacitor is impact by temperature and get wrong value over the time. I also repaired ME9.7 with the error related to misfire, ignition coil (P0351, P0353, P0354, P0356...) then the problem related to the ignition chip 30521 (this chip had two row and each row had 10 pins, you can goggle this chip for detail).
I don't know what chip component of the Me9.7 failure making radiator fan running like crazy, let me know if you have info.
Hello @knowbenz , warm regards from Hanoi Vietnam. I'm highly appreciated for your contribution support on the fan issue of S550, you advice is high valuable for all of us.
I have friend of my with S550 4Matic 2007, he also struggling with maximum speed of the radiator fan (sometime the fan activated with maximum speed and it should not). We suspected that problem are related to AC, we did replacement many thing related to AC such as expansion valve, Condenser. Dryer accumulator but it could not help.
Do you think the ME control unit is the suspected one for this problem and the next action we need to try is to replace ME control unit?
I would suggest diagnosing the problem over throwing parts at it. If you have access to SDS or a scan tool that will show fan request by ME you can easily see if AC is requesting fan or not. Then put a scope on the speed signal wire and see if it matches up.
I did ME9.7 repair few time, if there are problem with CEL on and error code related to (P0030, P0050, P064D, P064E, 1337, P2237, P0607) then problem likely due to capacitor in side ME9.7 circuit pack, capacitor is impact by temperature and get wrong value over the time. I also repaired ME9.7 with the error related to misfire, ignition coil (P0351, P0353, P0354, P0356...) then the problem related to the ignition chip 30521 (this chip had two row and each row had 10 pins, you can goggle this chip for detail).
I don't know what chip component of the Me9.7 failure making radiator fan running like crazy, let me know if you have info.
I couldn't tell you which one runs the fan but I'm sure whoever is taking it apart could figure out which one by tracing the circuit. Maybe it's the same one that turns on circuit 87 or maybe different.
I do know loose grounds on the valve cover will blow the driver for the coils though.
We typically don't mess with opening circuit boards for liability reasons here in the US
So I gave my ME to repair, but technician called me back, saying, that he doesn't see anything wrong, what usually would be related to the fan. So I took ME back home, into car, and today drove to him. He tested with star, and scope, and it doesn't show usual ME related problems. What he was suspicious about was AC giving messages : 94D9 and 94ED. As well as Stationary heater with remote control: 9151, 9054. He told me it could be faulty AC controller, but until these messages is present, it is impossible to properly test it. To clear these messages, it is necessary to disassemble dashboard, and check/repair/change actuator motors, at first. And go from there.
So I gave my ME to repair, but technician called me back, saying, that he doesn't see anything wrong, what usually would be related to the fan. So I took ME back home, into car, and today drove to him. He tested with star, and scope, and it doesn't show usual ME related problems. What he was suspicious about was AC giving messages : 94D9 and 94ED. As well as Stationary heater with remote control: 9151, 9054. He told me it could be faulty AC controller, but until these messages is present, it is impossible to properly test it. To clear these messages, it is necessary to disassemble dashboard, and check/repair/change actuator motors, at first. And go from there.
So I took car back home.
What do You guys think?
There is a screen showing actual values that will indicate demand requested by ACC. If that is zero and ME is zero yet your fan is on you have an issue that will be simple to diagnose based on scope patterns and information previously posted. I don't know what those codes are but the AC will request fan speed based on the pressure sensor reading. I didn't go back through and read but I recall your fan was coming on randomly with the car off correct? This will not be caused by the ACC requesting fan. I haven't looked into the internal circuitry of the ME module but I would think it's safe to say the fan driver is separate from the driver controlling the circuit 87 relay that typically causes fan to come on with car off.
There is a screen showing actual values that will indicate demand requested by ACC. If that is zero and ME is zero yet your fan is on you have an issue that will be simple to diagnose based on scope patterns and information previously posted. I don't know what those codes are but the AC will request fan speed based on the pressure sensor reading. I didn't go back through and read but I recall your fan was coming on randomly with the car off correct? This will not be caused by the ACC requesting fan. I haven't looked into the internal circuitry of the ME module but I would think it's safe to say the fan driver is separate from the driver controlling the circuit 87 relay that typically causes fan to come on with car off.
Hello again, knowbenz!
Yes, it is running when on high sometimes when engine is running, sometimes when it's off. The most annoying is when I get back home, shut the engine, and start to take my things of the car. Every time I open the door, it starts again, and runs for couple of minutes.
I don't understand what is Your point regarding circuit 87 relay?
You know, it's very hard to comment on someone else working methods. He told me, that he tested with scope, I don't know how he did it. Anyway, he was very aware of situations where ME causing this, moreover he's able to repair it. And he said it is not the case. So I don't know what should I do.
Here, I'm posting error list, regarding AC, auxiliary heating.
Yes, it is running when on high sometimes when engine is running, sometimes when it's off. The most annoying is when I get back home, shut the engine, and start to take my things of the car. Every time I open the door, it starts again, and runs for couple of minutes.
I don't understand what is Your point regarding circuit 87 relay?
You know, it's very hard to comment on someone else working methods. He told me, that he tested with scope, I don't know how he did it. Anyway, he was very aware of situations where ME causing this, moreover he's able to repair it. And he said it is not the case. So I don't know what should I do.
Here, I'm posting error list, regarding AC, auxiliary heating.
One fault of the ME is it randomly activating the circuit 87 relay. This is my point and it has been discussed previously. if the ME activates the relay with the car in the rested state it will provide circuit 87 to the fan. The ME will not be "awake" when it does that so there will be no PWM signal provided at 10% to keep the fan off. It will be battery voltage on the signal wire sending the fan to full speed. Refer to all the pictures I posted previously. This is literally one of the most basic circuits on this car and diagnosing it properly shouldn't take more than a couple minutes. Those fault codes have absolutely nothing to do with fan speed demand. We know he has an SDS so if you go into actual values in ME under suction fan you will get the screen below. If the fan is on high speed and there is 0% requested then simply scope the signal line and you will likely see battery voltage. If the request is 0% and it comes on when the car is off you have a problem. The only reason it would stay on after shut off is thermal management and it won't stay on that long. If that is the case you will see request from ME and likely high coolant temps.
I had the same symptoms as yours. I couldn’t Figure it out for the life of me sacred it by 2 shops nothing changed my fan in the case the regulator was bad! for almost 6months I delt with it . Mine started with replacing my alternator, in order to do so you need to remove the thermostat housing which drains the Coolant, after reassembling I had this exact issue. So after replacing the thermostat went on a ride I needed the air on, it was very low so I said that needs to be fixed now WTF? After replacing R134 refrigerant ran for two hours didn’t behave very different but in the morning after driving it for about an hour on the freeway doing errands she came back into Lane where she belongs LOL! seems to be working the way it needs to be. I’ll will leave you with this. If this is Mercedes way to say you are low on your refrigerant its the ****tiest thing I’ve ever experience :-) good luck guys it’s only been eight hours now could be very different thing in the morning.
Originally Posted by Simonas.st
Hi all,
recently while driving in the city, totally usual conditions, fan started to blow at full speed. And it's going crazy ever since. It starts at full speed, and cuts off whenever likes, even when car is closed and locked. Usually starts at high, when after driving around 30min. Yesterday just reparked, and it started to spool up after some time, when car was shut.
Any ideas?
P.S.: and I of course will go to STAR when I will have time (usually takes couple of months) . BUT, 90% I'm always solving with clever advice, and without STAR.
Hello,
I have the same issue... The MB dealer in my aera told me that I have yo change the fan. The regulator inside is out of order!
But when I read your posts, now I not realy sure to pay for that...
I had the same if not very similar issue. My radiator fan would turn on intermittently when the car was off and the key was away from the vehicle. I spent several days trying different things I researched w/ vehicles w/ similar issues. No need to go into steps that did not resolve the fan issue, but some was info I found in this same thread. Anyway, long story short I was hovering over my engine compartment waiting for the fan to turn on after parking and turning off my S-Klasse. Right before the fan actuated I heard a relay click in the the fuse and relay box in the left engine compartment. My hood was up and I had the cover off the fuse and relay box from previous troubleshooting of this issue, so I heard it loud and clear. I found the relay to be the K relay. I pulled it out & the radiator fan stopped. I then started the car. No dashboard warning indicators. I turned the car off and waited, nothing. I plugged the K relay back in and the fan began running, still w/ the car off. I swapped the K relay w/ the G relay which has the same part number. Vehicle now starts and turns off w/ normal radiator fan operation. I did hear the relay now in the G relay position click, but as of now I don't see any effect from it. Research says the G relay is the 15R relay and affects the slave wiper motor, master wiper motor, cigar lighter & restraint system control unit. None of those should be powered w/ the vehicle off, but if my wipers come on in the middle of the night I guess I'll know why. I will be ordering that relay shortly to be on the safe side though. I usually just read info off the forum, but joined and posted, because this issue seems to be one the biggest mostly unsolved vehicle mysteries according to various board posts. So hope this helps somebody.
07-11-2019, 07:03 AM
