W212 Radiator fan turns on when ignition off
10-06-2023, 05:14 AM
#1
Newbie
Thread Starter
W212 Radiator fan turns on when ignition off
Hi.
When i turn off the ignition and remove the key, the cooling fan, starts to run at high speed.
And fan stops when i turn on ignition.
I noticed that the fan doesn't run when ignition is off, and the diagnosic (a cheap one) is attached to the OBD.
I've checked fuses in fusebox in engine compartment.
Can the battery cause a problem like that?
While driving, I've a voltage over 14.5v and 12.1v when the car is shutted down.
Where do I start to fix this problem?
When i turn off the ignition and remove the key, the cooling fan, starts to run at high speed.
And fan stops when i turn on ignition.
I noticed that the fan doesn't run when ignition is off, and the diagnosic (a cheap one) is attached to the OBD.
I've checked fuses in fusebox in engine compartment.
Can the battery cause a problem like that?
While driving, I've a voltage over 14.5v and 12.1v when the car is shutted down.
Where do I start to fix this problem?
Last edited by Wisswass; 10-06-2023 at 05:26 AM.
10-09-2023, 08:00 AM
#2
MBWorld Fanatic!
Join Date: May 2018
Location: Jakarta-Indonesia
Posts: 4,396
Received 4,449 Likes
on
2,605 Posts
2014 - W212.065 - E400 ( M276.820, 3 liter Turbo) RWD not Hybrid
Hi.
When i turn off the ignition and remove the key, the cooling fan, starts to run at high speed.
And fan stops when i turn on ignition.
I noticed that the fan doesn't run when ignition is off, and the diagnosic (a cheap one) is attached to the OBD.
I've checked fuses in fusebox in engine compartment.
Can the battery cause a problem like that?
While driving, I've a voltage over 14.5v and 12.1v when the car is shutted down.
Where do I start to fix this problem?
When i turn off the ignition and remove the key, the cooling fan, starts to run at high speed.
And fan stops when i turn on ignition.
I noticed that the fan doesn't run when ignition is off, and the diagnosic (a cheap one) is attached to the OBD.
I've checked fuses in fusebox in engine compartment.
Can the battery cause a problem like that?
While driving, I've a voltage over 14.5v and 12.1v when the car is shutted down.
Where do I start to fix this problem?
Read the attachment
The answer may be there...........
The following users liked this post:
Wisswass (10-09-2023)
10-09-2023, 10:55 AM
#3
MBWorld Fanatic!
Join Date: Apr 2019
Location: Silicon Valley
Posts: 5,662
Received 3,448 Likes
on
2,297 Posts
MY'14 W212 M276 3.5NA @60kMi
Interesting case of busy fan...
Where you start to fix this is... by reading the WIS document carefully researched by @S-Prihadi then you understand the smart FAN has a mind of its own in this Bosch system.
There may be nothing wrong with your fan system because it is able to turn off ie. it positively receives ECU PWM control else it would keep blowing regardless of control.
Can you confirm your fan never spins on cold engine, right?
The voltages you report are coherent with normal function.
Go ahead, scan your car for codes then translate faults in plain English descriptions. This will provide us an idea of what's at play.
In addition go ahead and specifically read :
You will have empowered yourself by completing these checks.
There may be nothing wrong with your fan system because it is able to turn off ie. it positively receives ECU PWM control else it would keep blowing regardless of control.
Can you confirm your fan never spins on cold engine, right?
The voltages you report are coherent with normal function.
Go ahead, scan your car for codes then translate faults in plain English descriptions. This will provide us an idea of what's at play.
In addition go ahead and specifically read :
- Engine coolant temp sensor
- AAC pressure sensor
- (Coolant tank level !)
You will have empowered yourself by completing these checks.
Last edited by CaliBenzDriver; 10-09-2023 at 04:10 PM.
The following users liked this post:
Wisswass (10-09-2023)
