Nissan Repair: Nissan Frontier 2006, coolant level, radiator fans

Question
I have a similar problem with cooling fan coming on all the time  never did before also when the truck gets hot, and at a light, oil pressure gage drops and bounces this started after the transmission fluid was changed

Answer
Mike,

This was a coinsidence that the radiator fans come on after the fluid change.  I would look at the coolant level first.  If it is good then look at what the temperature is doing.  If it is hotter than you are used to replace the thermostat.  If the temperature is good then replace the temperature sensor that turns on the fan.  If the instruments are messing up as you say go to Autozone or Checker and get the electrical system inspected.  They will do it for free.  It sounds like your battery is going down.