V36 G35 Cooling Fans not working at all

[rileyingraham]

Hey guys, got an 07 G35 (V36) Sedan 6MT with a very specific problem that I haven't been able to find anywhere else on the forums - also, apologies in advance if this is the wrong sub-forum to post this in.

Here's a little history on the car just in case it helps:
I bought it not running and it needed an ECM. Got the new ECM, and replaced the BCM too just in case, had everything reprogrammed and replaced the fuel pump. The car runs fine now, but could use spark plugs. It's going to be part drift car so I unplugged the YAW sensor and brake switch sensor. There's signs that it has been hit in the front at least twice but only hard enough to just push the corners of the bash bar in a little. From the looks of it, the radiator and fan shroud have been removed before (lines are in weird places and just don't sit right) but there didn't look to be anything unplugged in the front.

Bottom line, the fans don't work at all. The fans don't come on when I turn my AC system on (though I don't have every part of it, the guy said "it needs a couple of lines and something that goes behind the battery") and they don't come on when the car gets hot. I can leave the car at idle and move it around a bit and the temps are fine but doing anything else will cause the temps to spike. I've replaced the PMW fuse (or PWM, can't remember the exact name) and the fan control module and still nothing. I was able to put direct power to it from the purple wire leading into the fan control module and the fans came on but other than direct power I can't get them to even move. I've even replaced my coolant temp sensor just in case something was wonky with it but that still didn't change anything.

If literally nothing else works, probably going to just wire them to a switch and manually turn them on after it gets to operating temps to save the hassle of tracking down whatever could be causing this. I'd rather not do that though because I want this to also be a nice street car too and I'd rather have everything work the way it should.

Any advice is appreciated!

[VStar650CL]

Those cooling fan modules are basically just big power-FET tran-sistors. When they fail open you get no fans, when they fail short you get constant high-speed fans. If you want to do diagnosis, at the fan control module pin 1 Black should be a good ground and pin 3 Red should be power from the Fan Relay (ignition). If 3 is cold then try replacing the Fan Relay. Pin 2 Violet is PWM, when you turn on the A/C it should show a "middle voltage". If it's 0V or Vbattery then your ECM may have an issue. If the signal is there then the fan control module is shot.

[rileyingraham]

Thank you for that! Pin 2 is where we applied power when testing if the fans would even work so we'll check the voltage on that line and see what happens. I'm praying that it's not the ECM because that thing was too freaking expensive so I'd hate to replace that one again. I'll also double-check the part number on it but it came from the same exact car - only thing that I can think of is the new ECM might have been from a different trim but I don't even know if that changes anything.

Will post an update on what I find.

[Caidrac]

It's the fans themselves *probably*. I had both fans go bad on my 2005 350Z. One went out at some time, but the one remaining was enough for a while. In heavy traffic around Albany, NY, I had a wift of steam come out of the side of the hood. As long as could keep moving and air flowing through the radiator, I was fine, but stuck in traffic on that 90+ degree day, It would overheat. I made it 300 miles home, and found both fans were dead. The full shroud assembly with both fans from Nissan was around $800. Two Korean fans was about $100. Replaced the fans and was good for another 3 years, then sold the car, therefore I can only vouch for those fans for 3 years or maybe 12000 miles.