Fan Stay-On: Cooler Fan Control

In various MSG (Multi-Server Gateways), there is a feature that allows the cooler fan to run for a period of time after the system has shut down.
The PIN assignment table for my AFN-MSG also includes a PIN for the after-run fan.
I assume that this wire is intended to connect to a relay for the electric radiator fan.

My question:
The radiator fan after-run function is only useful when the ignition is off. Does this mean that the engine control unit (ECU) can also process the coolant temperature value when the ignition is off and output a signal? Consequently, does the ECU have a quiescent current consumption?

At what temperature does it turn on/off? Can this be adjusted? Is there an adjustable time constant?

Regards,
Jens.

Quote:

At what temperature does it turn on/off? Is this adjustable? Is there an adjustable time constant?

That is certainly changeable, but it's essentially the same as chip tuning.


Generally, the MSA15 will switch off automatically. The timing of when it does so can be programmed "as desired."

m;

Jens 16syncro wrote:

Does this mean that the engine control unit (ECU) can process the coolant temperature value even when the ignition is off and output a signal? Consequently, does the ECU have a quiescent current consumption?

I should have looked more carefully...
Here /viewtopic.php?t=2750&highlight=l%FCfternachlauf at least explains how the MSG can, in principle, generate a radiator fan after-run.

The MSG doesn't need to remain energized for the entire duration; that's why there are impulse relays that switch off after a set time. A short current pulse is sufficient to activate the relay.

That would then be a simple timer with a fixed time value, meaning the fan runs for a time X after the initial operation, regardless of how "successful" the fan's after-run was.

Does anyone know any details about this function in the MSG?
I might actually need them quite soon.

Regards,
Jens.

Hi,

Martin already mentioned it: the MSG (Motor Start Generator) can shut itself off. That's exactly what the infamous relay 109 is for. It allows the MSG to stay on after the engine starts for as long as it wants, and then automatically cut off the power.

Don't you think a simple circuit would be much easier for your purpose? A timer that uses the temperature of the cooler or something similar as a basis for the run-on time could be quickly put together.

Best regards,

Jan.

Jan6K wrote:

Don't you think a simple circuit would be much easier for your purpose? A timer that uses the temperature of the cooler or something similar as a basis for the run-on time could be quickly put together.

Hello Jan,

Of course you're right, a simple follow-up circuit with a thermostat switch can be implemented relatively quickly. You only need a thermostat switch (which is already available), a pulse relay with a socket (which needs to be purchased), and a few meters of cable/crimp connectors (which are already available).

I was just thinking that if this function already exists in the MSG, it might be useful to utilize it. However, since it doesn't seem to be publicly documented how the cooler fan overrun function works exactly, I'll leave it as is.

Sure, here's the translation:

"Quick question about relay modules:"
I found some that switch off after a set time following a trigger on the control contact, regardless of how long the trigger lasts.
However, I wonder what happens if the control signal (which comes from the thermostat) persists even after the set time has elapsed (i.e., the coolant temperature is still above the limit). Will the relay then re-engage, or must there always be an initial activation sequence (i.e., does the continuous current have no effect)?

Regards,
Jens.

"Why don't you ask Rainer about it...? If the engine is installed in the T3, then it would definitely make sense to make some other changes as well. As I mentioned before, you could also adjust the activation conditions (I think so too), and you would have a clean solution..."

matthiasTDI96 wrote:

Why don't you ask Rainer about it...?

Hello Matthias,

I will do that sometime (i.e., after the mechanical modifications are completed).
If Rainer needs three hours of work to reprogram the after-run fan, I can probably set it up externally, which will be cheaper .

The external solution would also have the advantage that the parameters could be easily adjusted through a series of experiments.
You can buy impulse relays with an adjustable after-run time (easily adjustable via a potentiometer).
Thermostats with selectable (but not adjustable after installation) switching temperatures are also available.

Regards,
Jens.

... and a refrigerator running on battery power isn't that dangerous (as long as you have enough batteries).

m;

dieselmartin wrote:

... and a cooler afterglow isn't that dangerous (if you have enough batteries).

I would also only use an electric water pump, and the radiator fan would remain off. The auxiliary water pump is already installed and finally gets a real purpose with a water-cooled turbo.

Regards,
Jens.