ST3s FAN SWITCH

[snahmi]

Hello,

I have read a couple of threads about installing a fan switch on the ST series in order to be able to start the fan before the temp reaches a high level.
I have read the need to have the switch on a "hot" wire connected to the bike key, in order to avoid having a depleted battery in case someone forgets the switch on the "on" position.

The threads I have read had to do with the ST2 or -generally- with ducati non testastretta engines.
Fan Relay bypass question
Install Fan Switch on Non-Testa 4v bikes

I think there was a member called Motorsikelist who tried to do this.........
Has anybody else tried it on an ST3?
I am trying to find a solution that does not mess with soldering on the ECU pins.
AT THE SERVICE THEY TOLD ME THAT THIS MOD IS IMPOSSIBLE ON THE ST3 !!!!


Any help on this please?

[latte committee]

I left the original fan and circuitry alone.

But I installed a second OEM fan on the opposite side of the radiator.

I bought a used fan, fabricated additional brackets for attachement to the radiator, then ran seperate wiring for it, including a manually operated switch.

I've found it handy when riding in processions, parades, toy runs etc, and when stuck in slow moving traffic.

If the temp gets to 103, the standard fan cuts in, and depending on how long I'm going slowly for, it might run for 20 minutes, during which I've seen the temp climb to 112.

With the auxillary fan, I can pull the temp down from 103 to 97-100, in about 2-3 minutes, and keep it there for however long.


Fitting the auxillary fan took all of about 4 hours (fairings were already removed for another reason)
All up cost approx $80.00

[Maverick]

Originally Posted by snahmi

Hello,

..switch ..fan ..key-on only .. no messing with ECU
Has anybody else tried it on an ST3?

I have the (DesmoTimes) fan mod as well, and have no problem with it being functional with the key off. However, it requires only a simple modification to the original scheme to get what you want. You need to find a 12V signal that is only live upon key-on. You can use it to control a relay that switches the original battery-to-fan wiring. This way, the circuit is disconnected when the key is turned off.

If I am not mistaken (anyone correct me if I'm wrong), there is such a 12V signal under the dash that is originally intended for heated grips. It has an Amps Superseal connector.

Make sure you use a 12V-relay that can handle the current when the fan is running.

I hope that helps.
Cheers, Mark

[snahmi]

Thanks for your replies guys!!!

@ Trevor : Did the second OEM fan fit near the stock one? Isn't there anything that blocks the installation? You bought EXACTLY the same "flat" st3 OEM fan?

@ Maverick : The reason I opened this thread is that I was told that if you mess with the OEM fan you have to mess with the ECU....
At the service they told me that you can't bypass the ECU, and that it gathers a lot of parameters according to When it starts the fan etc....
This is the reason I am confused.
Ok, I understand that (regarding the connection to the bike key) I have to get a Key-on / Live signal from under the dash.
But then, how do I connect the 12v signal and the switch to the fan in order to have fan ON on demand , but in the same time NOT MESS with the normal Fan function (letting it start when the ecu wants, regardless of the switch position.)
Do you have any photos/schematics?


P.S I see you are from Switzerland..... I visited Switzerland by bike in 2010 (when I brought my ST3 all the way from Germany) and this summer (when my wife and I had a really beatiful tour in the Alpes Vaudoises + lac Leman area)
You have such a wonderful country!!!



Everyone please excuse me for the long post.

[latte committee]

Originally Posted by snahmi

Thanks for your replies guys!!!

@ Trevor : Did the second OEM fan fit near the stock one? Isn't there anything that blocks the installation? You bought EXACTLY the same "flat" st3 OEM fan?

< snipped >

@ Everyone please excuse me for the long post.

Mate ,,, it is sooooooo easy for people to misinterpret things on forums.
If length of post makes for clarity, then so much the better.

Original fan is located on the LHS of the bike.
I fitted the second fan on the RHS of the bike.
It is an OEM fan for my model 2007 ST3.
I fabricated brackets that gave a mirror reverse fitting to that on the LHS original.

There is enough space, and nothing has to be moved or modified.
I purchased the second fan from a dealer in the USA, via eBay.

Cost was $25.00 + freight.

I wired through a relay, directly from the battery, with relay energisation via a switch on the dashboard, which is powered from a circuit that is live only when ignition is ON.
There are plenty such circuits. I took mine from the horn, which is a seldom used circuit, with low current draw.

[snahmi]

Trevor, Humbly I Bow to your Ducati ST Knowledge!


Now let's find an ST3 OEM fan!

Thank you so much (again)!!

[latte committee]

Originally Posted by snahmi

Trevor, Humbly I Bow to your Ducati ST Knowledge!


Now let's find an ST3 OEM fan!

Thank you so much (again)!!

You are most welcome.

I have received so much assistance from others on this forum, on other matters, that it is my pleasure to share what I have and can with others in return.

Good luck with it, and please keep us informed on how it works out for you.

[tonered]

Or, you can do the ghetto method and just run a fused lead from the + terminal to a switch and then to the postive fan lead (blue wire typically)? I've been running with a non-fused lead for a couple years now.

Unless you park next to an active runway, you won't walk away from the bike with the fan on. It took longer to cut a square slot in the dash than aything else.

Have a good one.

[tonered]

Also, just throwing this out there. The last thing you might want is the fan starting with the key when you might be trying to start on a marginal battery conditon.

Have a good one.

[va duc]

So, it's not rocket science