battery drain- help needed

[realslimshady]

Originally Posted by Harley Dave

To ventilate the climate system's control system
the ventilation fan can be started up to 50
minutes after the car's ignition has been
switched off. The fan is then switched off automatically
after approx. 15 minutes.

As for the little cabin-temp-monitoring fan - I have never noticed it running.

Cheers

Dave

That's very interesting! I shall dig the manual out tomorrow and have a read, as it appears it is a 'normal' function. I want to see if as quoted it starts and then switches off again.
I haven't had time to check the CEM connectors yet, but they are on my 'high priority to do' list

[Moose Test]

Originally Posted by S60D5-185

Not quite that simple.
If you can tell me how an injector wiring fault can cause Transmission Service required on a D5 and be stuck in 3rd gear because it certainly can.

Not to be deliberately contentious, nor pour petrol but actually this can be explained.

The wiring fault either leads directly to signal integrity issues on the CAN bus, or at least one of its stubs, via the ECM. Or, the fault affects the ECM directly, which then indirectly affects the CAN bus by flooding it with garbage.
The exact mechanism notwithstanding, this ultimately leads to a loss of, or intermittent interference with, communication for all transceivers (CAN bus devices) connected to that bus, the transmission control module, amongst others. Hence, you see "action at distance", with the hallmark of multiple systems being affected with major symptoms.

Your example also demonstrates exactly why it is unlikely in this case to be such a wiring problem affecting the REM CAN bus - there's no way the effects would manifest themselves only as something so very specific as the CCM turning on the climate fan. They'd be major mayhem, probably non-working indicators and brake lights and floods of DTCs on view.

[S60D5-185]

Thanks Moose, I accept all of that but the point I was making is that the two issues in my example are so far apart that the vast majority would never believe that there could be any possible link.
My advice re keeping an open mind still stands but thanks for the input. 👍

[realslimshady]

Harley Dave's post does raise the interesting question of whether or not I've been sent on another wild goose chase - as the quote from the manual clearly shows that the 'random' fan blower operation is actually a feature of the design.
What would be helpful would be to know what parameters are used to make the decision to start the fan - 'can be started'....
Anyway. I'm going to run the car with aircon on for five minutes now, leave the fuse in and monitor it.
Report later.

[Moose Test]

Originally Posted by realslimshady

What would be helpful would be to know what parameters are used to make the decision to start the fan - 'can be started'....

That is an interesting question in and of itself. HOW does the CCM know that the interior of the vehicle is damp? To the best of my knowledge, it has only a sunlight sensor and temperature sensor available to it in the cabin. There's an air quality sensor but a) they are rarely working as they have a limited lifespan and b) it's sampling intake air. Without a humidity sensor, I can't see how this is supposed to work ever but nonetheless, it's a "feature".

I think the main question here is, is it working as expected? i.e. does it only run for 15 mins as per the manual, or as others have reported, it doesn't stop until it runs out of juice. Even if it does run to time, that doesn't rule out either a) the battery being on its way out and not being able to support the expected load for that duration or b) there's something wrong with the blower motor or its control module such that it is drawing more current than is expected and the battery, although within spec, can't handle that rate of drain.

What would be really useful to have available to you would be a data logging multimeter, so that you could leave it in the vehicle attached to the fan supply.

[realslimshady]

It's an interesting question Moose.
The car (and me too) is currently in central Portugal where it is most assuredly not humid and we're heading for our second >40 degree day, so I'm wondering if it is the dusty atmosphere it detects?
55 minutes after switching the car off the blower fan was running and exactly 15 minutes later it switched off, checked the (new) battery voltage and it's 12.59 so at the moment it all looks good, fuse box cover is back on and we'll run with it....
It does appear that the cabin temp sensor fan is running 24/7 though, anyone want to wander out to their car and put an ear by theirs?

[Harley Dave]

The original (not starting) problem was fixed by fitting a new battery.

The issue of the fan running-on seems to be more of a general query, not a show stopper, like it was when the original battery was weak.

Cheers

Dave