Auxiliary fan stays on

[Joezgo]

90 300zx.. Had the car for about 4 years working on it and the auxiliary fan has always stayed on when key is turned.. I have been all over the web and I have done everything that I found others had done and still nothing.. New coolant temp sensor, checked all all the relays under the hood. Swapped ones that are known to be good.. Checked all the plugs and connections to the a/c unit to make sure the high pressure switch wasn't causing the issue. I also have Nissan scantech and other software and not seeing anything wrong.. Still new to all of that though..O and I replaced the OE fan with the Taurus conversion and removed the auxiliary fan. The plug to the fan is still hot when key turned so I know there is still an issue and I need to fix it as soon as I can.. Does anyone know if I may have issues with the ECU? Not sure if the aux fan being on or having constant power is causing the car to use more fuel or not..

[DCaff300ZX]

Welcome!
I can't help specifically but can say that the aux fan is driven by the use of the climate control system, which mixes cold and hot air for the desired affect...bottom line is somehow your aux connection is on and most likely from some climate control connection or issue. I'd check the switches for the cl. control for corrosion/continuity and troubleshoot the system using the fsm...anything else will just be more questions than answers, as you have found.
Having the aux fan on won't significantly affect driving mileage unless it's enough to cool the engine too much (as a bad clutch fan can), but would cause the fan to be used more than intended.

[Joezgo]

Thanks for the tips but remember I don't have the fan hooked up any longer.. I have also checked the climate controls and plugs and so forth. I even went as far as pulling the dash out.. Had to fix the actuators,put in heater core,and new brake booster.

[amc49]

You can have live power in a hundred places (all cars do anyway and normal) yet if the live power cannot get to a load or ground then it turns into potential power instead of kinetic, meaning it sits there doing nothing. Simply tape off your plug with the hot wire as short protection and motor on. You may have ECU issues but if they are transparent then who cares? Don't worry unless further issues rear up to darken your day.

[Ace2cool]

^+1 to what amc said. If the issue is that your wire is hot, then as long as it doesn't find a ground, it's not an issue to me.