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.

Thanks.

Plutoe

Faulty fan controller!

Simonas.st

Head about this. What is puzzling with that idea, is that it's working high NOT all the time, but turn on and off, and also turns on, while car is locked. As far as I've read, faulty controller will make fan work on high revs all the time the car is running, which is not the case.
What do You think?

Simonas.st

More ideas are welcome.

knowbenz

Have had ME cause the issue

Simonas.st

And ME stands for?

knowbenz

Motor Electronics

the engine control module

Simonas.st

Hello again, it took a while, but I've got to dealership.
They have found no faults, than waited till fan will start, and checked if signal comes from AC, or ECM, found nothing there. Then, they have updated software (because driver's window didn't worked), and fan stopped fooling around, but not for long. After hour, when they have started the car to bring back to me, fan started run on high again. Since there were lots of messages about low voltage, they suggested to change aux battery. I did that, but nothing has changed.
What is interesting though is that I feel new battery again running low, because interior lights comes up and when I open the door, and turns off too quickly. And they does not turn on again, even if I push the button. Same was with old battery.

Maybe somebody is interested to dig deeper and help me to find the cause of this. I know, it's very easy just throw new parts in, but I'm interested in fixing things, not changing.

I don't know how it could be related to low voltage, but I've noticed, that fan starts every time power is used (when car is not running). For e.g. I sit in the car one hour, engine shut. If I move my seat, open window, open door, it starts up.

Any thoughts?

Finer6527

[QUOTE=Simonas.
Since there were lots of messages about low voltage, they suggested to change aux battery. I did that, but nothing has changed.
What is interesting though is that I feel new battery again running low, because interior lights comes up and when I open the door, and turns off too quickly. And they does not turn on again, even if I push the button. Same was with old battery.

I don't know how it could be related to low voltage, but I've noticed, that fan starts every time power is used (when car is not running). For e.g. I sit in the car one hour, engine shut. If I move my seat, open window, open door, it starts up.

Any thoughts?[/QUOTE]


If the new battery is not staying charged then you will get all sorts of electrical faults. Sounds like its not charging the new or old battery?? Alternator, wiring from alternator.

ItalianJoe1

If it comes on anytime the power is used, it's related to the CAN being woken up by another module. Since you say power seats triggered it, I'd have to assume it's the body CAN, which can send a fan request because of the a/c controller on it.

You really need to see what is commanding the fan on when it comes on, there's no way it's "not the A/C or ECM". It has to be something, and if it's really nothing, then the controller is just defective internally.

alx

this. i have seen many controllers fail in dazzling variety of fashion- some just go dead. others go full speed. then there are the girly ones- passive aggressive - go on and off when they feel like- no rhyme or reason.

i would start reading values when fan is working- if star says "fan running" then something is triggering it. if fan is running but system has no idea it is- see my previous paragraph

Simonas.st

Do You have any idea how to check if it's charging, or not?
Today I've entered service menu. (pressing ok and answer call buttons). While engine was shut readings were 11.5V, than fan kicked in, and it has dropped to 10.5. Fan turned off, and it climbed back to 11.3. Then I've started the car and it came up to 13.5. Does that say to You anything? I don't know which battery reading it shows.

Simonas.st

What is CAN? I've checked today, that nothing triggers fan for a while, when I stop the engine, but after some minutes it starts without any obvious reason (for me), or if I open windows, doors.

Simonas.st

Is there any way to check controller itself? Or just by crossing out other possibilities?

By the way, nice writing style.

alx

you can activate fan via das/ actuations. if it responds to das commands it is a safe bet controller itself is good

Simonas.st

And it's possible with STAR only, right?

knowbenz

Have had ME cause very similar issues.

Simonas.st

Bump.

alx

Correct. Actuations are star/ das only specialty

knowbenz

Do you have a scope? Monitor the PWM signal line to the fan. This is a very common issue

knowbenz

Are you referring to the M.E. when you say controller?

Simonas.st

Didn't understood. Maybe language barrier. Could You please explain?

Simonas.st

Guys, I've found controller being sold separately in Germany. What do You think?
http://www.ebay.de/itm/Steuergerat-G...0AAOSwLcNZWjso

Of course I should be sure, that it's faulty before ordering.

knowbenz

There is a signal wire that tells the fan what speed. It is PWM signal. Say for example the known issues of these fans getting water in them causing random activations you will not see a PWM signal to the fan, it's an internal short. Now say your fan doesn't come on but you have a good signal to it like the one pictured then the M.E. which sends the signal is good and the fan is either bad or it doesn't have the other power and ground inputs. I have seen when the ME is bad that signal wire will have straight 12v to the fan. You can sometimes hit the ME with a screwdriver or something and it will trigger the fault

But again, could be a number of things. I have also attached some screen shots of closed cases through mercedes.

knowbenz

That picture the fan is around 30%, this one the fan is around 90%