Crazy fans wont turn off

[Bowdog]

OK, this is driving me nuts. When I switch off my bike (K8 Gen2 2008) and take the keys out, the fans keep running, draining my battery. The only way to stop it is to disconnect the battery or pull both fan fuses. After scouring the forums I replaced the Cooling Fan Relay - it didn't fix it. The same behaviour occurs, even if the fan relay is removed!

I did a heap of testing with my multimeter and found that the problem only occurs when the right fan is plugged in.

I checked the manual's wiring diagrams and the two fans are controlled by the same logic - ie both on or both off, not individually controlled. The only thing that splits the two fans' behaviour are their fuses. Continuity tests seem to be fine for both fan plugs and fuses. When the Fan Relay is plugged in, both contacts for the right fan are at +12V. When removed both are at 0V. But either way, the fans still spin up. On the left, one contact is +12V and the other is 0V (as I would expect).

I did the amp draw test described in the manual and the right fan is working perfectly (.1A).

Here's the weird thing: If I plug the right fan in, both fans spin. If I pull the right fan fuse, the left fan still spins. If I pull the left fan fuse, the right one still spins. If I pull both fuses, they both stop (Phew!).

Before I install a manual switch to control the right fan, does anyone have any ideas?

Thanks,

Bowdog

[shorty]

Hire a priest!

The bloody thing is possessed!

[99er]

check coolant temp sensor

[Batfink]

HI Bowdog,

I could be completely off target as usual but a question first......

did you buy bike new or second hand?

I am just thinking that maybe someone else might have put in a manual bypass for fans already and you just don't know where the on/off switch is?

if you got it new then I suggest you follow shorty's idea of gertting a priest LOL

[Camel]

Gen 2 fans are controlled by ECU. Check coolant temperature, also check as per batfink's comments.

[Shordy]

On most cars, the fans will come ON when the temp sender is DISCONNECTED.
If the Busa is the same (and I'm not sure if it is or not), it could be an indication that the sensor is buggered, or something as simple as the plug is not connected / seated properly.
Worth checking....

[Bowdog]

I am just thinking that maybe someone else might have put in a manual bypass for fans already and you just don't know where the on/off switch is?

Good idea, but I've got my baby in a million pieces - there's no place for hidden switches to hide now.

---

it could be an indication that the sensor is buggered

That could very well be the problem. I'm not sure why it doesn't spin both fans, though. According to the wiring diagrams, the fans both share the same +12V and grounds. I'll rip it off today and have a look. That will be a million and one pieces to put back on Thanks to all!

Bowdog

[Batfink]

Sounds like you have given yourself a million piece 3D jigsaw for christmas LOL

[Bowdog]

[ROD]

Post on the AHC facebook page as well

https://www.facebook.com/groups/144056302464604/

[Bowdog]

I didn't know we had one! Just requested to join now :)