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Having a issue with my 2011 E220 CDI.Working to fix a P0101 error after service. This fault is still under investigation
When working on this I got a new fault.
Whenever I turn of the car (even after running it for 2-3 seconds) the radiator fan will start blowing at maximum speed.
Only way to stop it is to pull the cable from the fan.
When running the car without the fan connected, I get a P0480 error.
Mercedes checked the error codes for me and looked over a few things regarding the P0101. They mentioned canbus problems but won’t give out more information as they want to fix it themselves… (damn people).
The fan problem started after pulling the cables from the ECU to check for corrosion etc.
Tried pulling the cables again but it wont stop.
BUT!
When I turn on the ignition (not starting the car) the fan stops. Fan is working normally when driving.
This makes me think that the ECU is working as it should and that the problem is somewhere else.
Any ideas what to measure or check?
The fan assembly gets a signal from the engine computer (ME), if that signal is not present the fan will default to high speed. The ME controls the fan speed based on engine parameters AND request from climate control (when running A/C).
Tugging wires on the ME, you may have damaged the wire or pulled it from the terminal.
Really need a scanner to determine what the ME is requesting for output when all this is happening. Then ensuring you have good powers and grounds at the fan module. Finally a scope of the signal to the fan module would rule out whether its a fan or ME issue.
BMW is always spot on, the fan acting up involves the ECU being in the weeds.
Perhaps I am getting this wrong... it seems that somehow you've pulled a weird combination: Fan running with everything Off (Key off, cold engine Off, A/C Off).
I jumped in because this seems like a No-No condition!
The fan can only run if the F-SAM "FAN-ON" signal wakes up the fan controller
-> So I'd check for a bad 60Amp GND making the fan module act-up with a floating reference.
Do a quick batteries power cycle to sanitize the mind of your ECU... then go to town with ECU wiring and connector if you have to.
A missing ECU PWM signal makes the fan logic run full speed but that's only with a FAN-ON condition.... right?
++++ Electric COOLANT pump:
ECU may be running the fan for a while after Key-OFF if the engine needs cooling... but not with a cold engine!!
🙂
Last edited by CaliBenzDriver; Aug 18, 2021 at 05:27 PM.
01. Check X25/2 connector. PDF attached.
This is the PWM signal intermediate connector prior to the big connector/s of the engine computer .
This wire from your diesel engine computer N3/9 to pin/terminal 4 of the M4/7 cooling fan connector.
02. Make sure your radiator shutter ( if installed ) is not defective.
03. Check fuse 22 at Front SAM and its relay N.
Fuse 22 also link(powers) the front SAM to M4/7 cooling fan's pin/terminal 3 connector.
There is also a feature of delayed fan OFF untill about 6 minutes after engine shutdown, at 40% fan speed..... if certain "hot" parameters met.
Supposedly IGNITION ON will not defeat above process.
Attached the PDF on this subject
Can you help us all brain storm this Cooling Fan PMW signal ?
This can relate to all our cars. I am very curious on the description of its function which is conflicting if based on the 4 documents I attached.
Attached 4 documents describing the cooling fan M4/7 operation.
I find the Cooling Air Flow Basic, FUNCTION is probably too old and not accurate for the PWM information, albeit it is a year 2020 print. What do you think ?
Let's assume 10% duty signal as fan motor OFF command, as explained in 3 THERMAL MANAGEMENT documents.
The value of 10% as OFF is not an issue , but what I am confused with is, why would the engine computer need to be awake 100% of the time,
to produce a duty signal of 10% to make sure FAN STAY OFF ??
The Fault condition to produce maximum fan speed is explained different for M651.9 compared to gasoline engines M276.8 ( 3.0L Turbo ) , M276.9 ( is this the 3.5L NA ? ) and M157.9
In M651.9 document it stated :
If there is a malfunction in the signal line (loss of frequency) from the CDI control unit, the internal combustion engine and air conditioning fan motor
with integrated control switches automatically to the maximum rotational speed (fan emergency mode).
In the gasoline engines, it stated :
For faulty actuation the fan motor rotates at its maximum rotational speed (fan emergency mode).
Its status is transmitted to the fan motor as a ground signal over the actuation line. So the signal wire pin 4 of M4/7 is grounded ??.......................... is this a Zero Duty cycle or Loss of Signal ?
In ALL CAR, Cooling Air Flow Basic
Fan emergency operation
In the case of a fault in the signal line (loss of frequency) by the powertrain control unit, the fan motor switches itself to the maximum rotational speed.
The engine computer, be it N3/10 of the gasolines and N3/9 of the diesel has fuse 27 from Front SAM as their 30z, the continuos power untill battery cable/s disconnected.
The rest of the engine computer power come from fuse 22,23,24 and 25 ( Via Relay N ) at least for M276.8 and M27.9 and this need Iginition Key in Position 2 ( dashboard warning lights up , before cranking)
for this power to be activated.
OP mentioned his "problem" fan will shut off with Ignition ON ( engine off ), which I believe he meant Ignition Key Position 2.
In Key Position 2, pin 3 of M4/7 get +12V signal via Fuse 22 for his diesel and our gasoline engines.
Now back to the original question I can't seems to get off my head.
Why would the engine computer need to be awake 100% of the time, to produce a duty signal of 10% to make sure FAN STAY OFF ??
Some other technical explanation I think is missing. There must be a sleep-state or sleep-mode for the fan which does not need the 10% duty signal .
We know that M4/7 fan working power is from F32 terminal MR4. This is the most upstream circuit 30, it is not via K2 relay which is 30g.
So, its power supply is non interupptable until its fuse blown or battery cable get disconnected.
thank you Surya for helping us dig into the ways the radiator smart fan module works
Smart FAN Mgt
FAN has 4 wires (diagram lower left corner):
It gets ALL_Time power from 100Amp Prefuse link and GND from a nearby post (hum)
It has a wake up CTL line from F-SAM to Enable the fan built-in controller logic to work or put it back to sleep entirely.
It decodes the duty cycle from PWM line to derive fan RPM requested by ECU.
A failsafe mode is achieved by minimal duty cycle of PWM to mean FAN _OFF while it is enabled by CTL line.
A missing PWM signals runs the fan at full rpm to protect overheating the engine and waste the fan bearings when ignored long enough.
My personal interest would be to learn what makes these fans disfunction....
++++++ Translation table: PWM to RPM
0% > Failsafe full speed
10% > 0% fan not spinning
20-80% > 10-90% RPM proportional speed
90% > 100% full spin 🙂
++++ Cherry on the cake:
I am super curious to look at the care MB worked in the 60+Amp GND point solution located behind left plastic wheel well.... may be slatted for tomorrow afternoon hands-on time.
Last edited by CaliBenzDriver; Aug 18, 2021 at 01:07 AM.
WOW...is that diagram by ALL DATA ?
It is so nice & easy to read !!!!! It group up all related components governing M4/7, no need to be in a migrain state looking at MB WIS...
It has a wake up CTL line from F-SAM to Enable the fan built-in controller logic to work or put it back to sleep entirely.
Aha, they provided the above info too ?
So the engine computer pin out for LUES signal to M4/7 fan , is a PMW signal and also capable of other signal , the GO-TO-SLEEP signal ... yes ?
You can get your Mitchell schematics and TSB's here - Enjoy
They are now owned by the Snap-On tool company.
I think this service is a good addition to your excellent design docs in WIS.
What I understand...
The ECU uses the Fan "LUES" signal to control the fan RPM from 0 to 100%.
The small curve ball here is the fan interprets 0% as FULL speed and 10% as STOP, then 20% as SLOW and up
This type of legacy signaling is really begging to be replaced with a two-way LIN control line!!
The nice part is the power supply is unswitched directly from Prefuse, there is minimal drop voltage under 60+Amps.
You can get your Mitchell schematics and TSB's here - Enjoy
They are now owned by the Snap-On tool company.
I think this service is a good addition to your excellent design docs in WIS.
What I understand...
The ECU uses the Fan "LUES" signal to control the fan RPM from 0 to 100%.
The small curve ball here is the fan interprets 0% as FULL speed and 10% as STOP, then 20% as SLOW and up
This type of legacy signaling is really begging to be replaced with a two-way LIN control line!!
The nice part is the power supply is unswitched directly from Prefuse, there is minimal drop voltage under 60+Amps.
Hello Cali, my X164 GL550 have the exact problem as the thread starter and I'm at the a dead end.
When ever I turn off the car, the radiator fan would come on full speed. It only stop if the key is in the signal range (I have Keyless go on mine car), or if I open the door.
I have a donor car so I have tried to swap things like radiator fan unit, front sam, engine fuse box... but the problem still there.
While playing with the fuse box in the engine compartment, I figured out that If I pull out the fuse 105, then the problem is no longer exist. However, I believe this isn't right and running the car without fuse 105 might cause other problem.
Could you please suggest what to look at next?
Thanks
Hello Cali, my X164 GL550 have the exact problem as the thread starter and I'm at the a dead end.
When ever I turn off the car, the radiator fan would come on full speed. It only stop if the key is in the signal range (I have Keyless go on mine car), or if I open the door.
I have a donor car so I have tried to swap things like radiator fan unit, front sam, engine fuse box... but the problem still there.
While playing with the fuse box in the engine compartment, I figured out that If I pull out the fuse 105, then the problem is no longer exist. However, I believe this isn't right and running the car without fuse 105 might cause other problem.
Could you please suggest what to look at next?
Thanks
All your controls seem to be working as designed. No issue there beside fan spins crazy under various conditions.
Yes we may have easy fix:
-- Use your scanner to read the AC PRESSURE.
When the sensor fails it drives the ECU nuts to spin fan.
-- Read coolant temperature from ECU.
You have to figure what is upsetting the ECU Logic. The fan itself seems to be responding safely.
All your controls seem to be working as designed. No issue there beside fan spins crazy under various conditions.
Yes we may have easy fix:
-- Use your scanner to read the AC PRESSURE.
When the sensor fails it drives the ECU nuts to spin fan.
-- Read coolant temperature from ECU.
You have to figure what is upsetting the ECU Logic. The fan itself seems to be responding safely.
Thank you for your reply, I have tried almost every thing related to the Radiator fan and A/C system but no hope. Finally I have to take it to the local mechanic and this is what he found...
apparently the previous owner have modified the wire behind the power outlet in the front passenger side , which lead to fuse 105 alway have power running through. That what makes the fan run at full speed when the engine shut off. After correcting the wire base on the WIS diagram then everything is normal again.
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, which lead to fuse 105 alway have power running through. That what makes the fan run at full speed when the engine shut off. After correcting the wire base on the WIS diagram then everything is normal again.
the ex-owner did
