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D.I.Y ECM/ECU fan blower replacement

107K views 95 replies 30 participants last post by  bwind 
#1 ·
simple to check if yours has failed (this applies to any R170). open up the lid to black box compartment in engine bay where ECU is located. turn the car igntion to the ON position (2) but no need to start the car.

go back to the box and move your hand around the top (dont touch anything) and see if you can feel any airflow and or hear the fan spinning. if not it has failed.

to fix this, 2 options. 1 buy a new fan from dealer (a lot of $$ for something so simple), or 2 replace the electric motor inside. i found this one on ebay and confirm it works. simple to do with a person with some know how.

MM36 DC ELECTRIC MOTOR,HIGH TORQUE,12V TO 24V,FOR WATERPUMP,FAN,ELECTRIC CAR ETC | eBay

replace the motor and re-solder the wires put it back together and done. reason for the failure (i opened up the old motor) is basicly wear and tear the motor has reached its life cycle. given how many of you have this car and the age yours will or has failed.

cooling the ECM/ECU is important especially on left hand drive cars where the ECM/ECU compartment is near the exhaust manifold...

these few bucks can save you forking out thousands on a new ECU/modules....

please check yours!
 

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#40 ·
glad to have saved someone from a fried ECU :D

the black powder you found in the housing/old motor is the dust from the old bushings all worn out...
 
#42 ·
the ECU is either one of 2 bosch or siemens

pre facelift SLK bosch ecu - runs all the time (confirmed with the 230, dont have anyone with a 320 to check)

post facelift SLK siemens ecu - runs all the time (confirmed in the 320)

it stands to reason it should do the same with the siemens ecu post face lift 230 too? i cant see them changing it specificly for one motor? the only thing different in simple terms between the 2 cars is the motor and options like heated seats etc. the cars electronics to run it are the same?
 
#44 ·
good information to know. so it is more or less confirmed the fan spins continuously (key ON position or engine running)... regardless of pre/post facelift or bosch/siemens ECU or slk230/320 etc
 
#45 ·
Finally got around to doing this - the motor has a circular mark near the terminal - connect positive to the terminal with the dot beside it for the correct rotation, I noticed that the one I removed had a red ring around the circular indentation. Took minutes, will probably prolong the life of the car a fair bit...

The rubber insert has slots to align with the cooling vent on the motor body.

 
#48 ·
Radio Shack $5.99

Just replaced my ebox fan motor with the Radio Shack $5.99 motor described earlier.

RadioShack Super Speed 9-18VDC Hobby Motor : Hobby Motors | RadioShack.com

Quick and easy. The motor was nearly identical to the one that had burned out. I got lucky and had soldered it in the right way first time when I checked the blower hooked up, but not installed.

A fairly easy DIY on my 1998 ML320.

The motor shut off automatically after about 4 minutes, started with key in Ignition.
 
#52 ·
i cant remember what i used but i think it was a flat head screw driver gentlty rocking it to pop it off. i sprayed some wd40 to help get it out (not sure if it did anything) but it slid off.

just go slow and it will slide off!
 
#53 ·
hello subby, i just check the motor on my ml 270 cdi and it was full of black pieces of carbon and dust inside, it can't be used again, i found a new motor from the windshield washer pump from a w210 mercedes , it says that is 12 v, i put it in the ebox fan housing everything works fine, but when i was closing the top of the motor housing the filter broke down in 2 pieces, it is safe to use the motor without this filter. thank you for the thread, my didn't work and i found that thanks to you.
 
#57 ·
have you got a pic of the little filter on your car? it probably wont mater. post a pic if you can
 
#59 ·
was responding to jorgji's post regarding his ml 270

" but when i was closing the top of the motor housing the filter broke down in 2 pieces, it is safe to use the motor without this filter. thank you for the thread, my didn't work and i found that thanks to you. "
 
#61 ·
i would say prob not a good idea but would like to confirm with electronics experts on forums. it looks like a "noise filter" of some sort to reduce electrical noise from the DC motor.

it may matter as the motor is right in the middle where all the computers are, and electrical noise interference can cause problems with them working correctly...
 
#63 ·
probably overkill and cutting a hole is a bad idea as dust, dirt and possibly water can get in... wait to fix the internal fan its probably a better idea
 
#65 ·
hello again, i found a motor for my fan, it was from a air pump, before this i fixed the "noise filter", with glue and then soldering the two pieces again, till now everything is fine, i tested the filter it worked fine, reassembled the fan put it back to his place in the ebox and turn key on, i hear the fan working, but when i was inside dhe cabin you could hear the fan like it was inside the cabin, it was to much noise, and after a close inspection i noticed that the fan gets air form the cabin vents tubes:
1) if i turn on the cold air i can feel it in the ebox
2) same with hot air

it seems to me that the ebox fan uses air form the cabin air filter, everything works fine exept the noise, it is like you are driving the car with open windows.
what can couse this, maby the motor is to powerfull for this fan, i can say that he blows a lot of air . thanks again.
 
#66 ·
I found a pretty good replacement motor, here, for $2.30. Flat rate shipping and handling in the continental US is $7.00, actual shipping costs for everywhere else. The physical size is the same except the shaft length is nearly twice as long. You can cut it to length but that's not needed, the excess is harmless and not in the way.

The Radio Shack motor is rated at 24,000 RPM at 18v, which would put it in the range of 17,000 to 18,000 at the vehicle's 12-13 volts. Couple the high speed with it having copper brushes and longevity is not very good. My brushes were almost completely worn down after less than 6 months, and that was with 4 diodes in series to cut the voltage down to about 10v to lower the speed/reduce noise.

The motor I found is rated 4000 RPM @ 12v, about 4400 @ 13.2v. On my bench it draws 0.14 amps while the original Bosch drew 0.13 amps. Physical dimension is the same 27.5mm diameter, 32.5mm length, 2.3mm shaft diameter but the shaft length is 25mm vs. 14mm. There's no detectable difference in air flow. It uses carbon brushes as does the Bosch, rather than copper. It is very quiet in operation.

NOTE: It comes with red and black leads but rotation is opposite if you connect red as positive, black as negative, so reverse the leads. It also has a capacitor across the leads you should remove so as to not change values of the LC noise filter on the original circuit board.
 
#67 ·
Just wanted to add my recent experience when a 2003 SLK200K module box fan motor failed short circuit. It burnt the multifunction module circuits traces at pin 58 (circuit 15) and also pin 75 (circuit 30E). A replacement module went the same way when the ignition was turned on. I have seen posts on other forums asking about the burnt circuit traces but as sometimes happens no solution was given.

It would seem from this thread that the motors fail open circuit and that makes sense for the brush motors but perhaps this failure mode is just for brushless motor failures.

I think a better solution would be to disconnect the fan motor from the multifunction module and connect it to the fused circuit for the radio. That way you'd know to check the fan motor when the radio stops working. It's on my list for my 1999 SLK230K.
 
#83 ·
Just wanted to add my recent experience when a 2003 SLK200K module box fan motor failed short circuit. It burnt the multifunction module circuits traces at pin 58 (circuit 15) and also pin 75 (circuit 30E). A replacement module went the same way when the ignition was turned on. I have seen posts on other forums asking about the burnt circuit traces but as sometimes happens no solution was given.

It would seem from this thread that the motors fail open circuit and that makes sense for the brush motors but perhaps this failure mode is just for brushless motor failures.

I think a better solution would be to disconnect the fan motor from the multifunction module and connect it to the fused circuit for the radio. That way you'd know to check the fan motor when the radio stops working. It's on my list for my 1999 SLK230K.
I know this is an old thread, but does a 2001 SLK230 have a blower fan in the module housing? Trying to track down a problem with pin 58 on the N10-3 Module.
 
#69 ·
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
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