25-cent Fan Mod

[WitchyWndy]

Ok, here is what I observed. I had set the low mph fans to kick on above 150 with the AC off. My temp was running around 177 to 179 and with the system turned off, they came on, although I'm not sure just how many fans were on, I only saw two between the radiator and engine, but I thought there were 3 fans because I had to set the settings for HS fan, MS fan, and LS fan. I figured I'd only keep these settings on race day to avoid burning up the fans. I think my issue, however is that they only come on with the engine running. I think the .25 mod will keep them running when the engine is off, correct? That could be the reason to do it via the jumper vs the diablo...

Bingo! The jumper allows the fans to be on with the engine off.

[gunracer]

had anyone ever thought about unplugging the fan harness at the fan and using like a small marine battery to power the fans them self so you dont have worry about draining your battery and they can stay on longer?

[Jaak]

The mod outlined above forces one fan to high speed mode and disables the other fan for low speed mode, but still allows the FCM to enable it for high speed mode.

If you pull a different relay and put the jumper here, instead, you force both fans on, and the mode is controlled by the FCM. So they will go low speed, or high speed, as determined by the FCM, but never off.

Attachment 42059

If you want both fans on high speed mode, then you must pull three relays and put in three jumpers as shown here. Make sure you use wire that can handle the current of the fan in high speed mode. (e.g. 12 gauge)

Attachment 42060

It's a simple mod, just like the original outlined above, but requires three jumpers. The next step is to actually wire in a three position switch to do this from inside. Easy....

I apologise if I've driven this up over the 25 cent level...

Fixed picture links as requested by PM.