Cooling fan questions

[GSPete]

Im new to the Ducati world so I am still learning the beast.

I have a 2002 Monster S4.

The right side cooling fan does not come on.

According to the schematic in the factory service I bought, the fans share a common power source.  i'll by that but, even when the key is in my pocket there is battery voltage at both right and left fans.  Is this to be expected?

Again according to the schematic in the factory service I bought, the fans have independent grounds.  The right fan ground has continuity with chassis ground.  The left fan ground is open.

The factory manual has a check for the cooling fan relay but the above system does not support a relay and if i am wrong can someone let me know where the relay is located? i have looked all over with no luck.

I am assuming the fans are controlled by an ECU.

The other theory is the left fan comes on and at a higher temp the right fan comes on.

Maybe the right fan is redundant; the bike has never overheated the fan comes on at 220 and cools the engine right down.

I am looking for someone to tell me how this cooling fan system works.  The local Ducati dealership has not been much help.

Thanks in advance for any help

[minnesotamonster]

http://ducatimonsterforum.org/index.php?topic=12572.0

this should help.

[GSPete]

Thanks for the info, very good. 

But what actually turns on the fans?  The fans have battery voltage 24/7 key in or out.  I need to know what closes the ground circuit.  The schematic shows individual grounds leaving the instrument cluster.  I am trying to locate what and where the actual switch takes place to close the ground circuit.  I know I'm being very anal but I am sure it is not the temp sensors closing the ground circuit, is it something in the instrument cluster that controls that switch? 

I am beginning to think that the left fan (the fan that does all the work) comes on at about 220F (which it does) and then the right fan (the fan that sits there and waits until its almost to late) comes on at or near the (High) temp of 248F.  Does that sound reasonable? 
   

[1KDS]

I don't have a 4V monster so I have no FHE, according to the link above your fans should be coming on sooner.  Reading 220 on the display is probably ok but I would think the second fan would come on shortly after the first.

The cooling fans operate sequentially according to the following:
With the temperature increasing, the first fan is energized at 101°C / 213.8°F, the second fan in energized at 102°C / 215.6°F.
With the temperature falling, the second fan is de-energised at 101°C / 213.8°F and the first fan is de-energised at 100°C / 212°F

[Speeddog]

The ECU provides the ground circuit for the fans.
So it's a bit odd that the ECU is turning them on at those temps.

There's 2 thermosensors, one provides the data to the dash display, the other to the ECU.

'01 and '02 Monster S4 are different in this area of the wiring harness, so '01 and '02 ECU/harnesses aren't compatible.

[GSPete]

I think I'm going to stop sweating it since it has not overheated in the high temps in traffic.  I would like to have someone test it but at the same time i don't want to get &%$#@*. 

If anyone has any other input I would really like to have it and thanks to who has already responded.   

[DucHead]

I'm running only the left fan, and the bike only reached 250° F ("Hi" warning) once, and that was whilst sitting in Pittsburgh traffic at 90+°F a few weeks ago.

[GSPete]

Speeddog, i noticed you have an '02 S4.  Do both of your fans come on?

[Speeddog]

Speeddog, i noticed you have an '02 S4.  Do both of your fans come on?

I'm running an aftermarket ECU (FIM U59) so it's not really a valid comparison.

Back when I was running the stock ECU, both fans would come on at the same time.

FYI, an '02 S4 with an '01 DP ECU will only run one fan, due to pins/wiring harness differences.