seanjordan20

Yeah but ISTA doesn't just test on an off functionality. Also with my Launch it tests the whole system. The sensor tested good also during activation tests. The system as a whole turned on and off like it should be. That's why this is so puzzling because with the capabilities of ISTA and my Launch I should find the issue but everything in the system is good. I guess when I doing the cooling system refresh I can install a new fan since It is 16 years old.

donpb

If you disconnect the PWM signal and the fan still turns on, its a bad fan.

donpb

I was just reading how the coolant temperature sensor and also the a/c play a part in it.

If the coolant sensor is disconnected (or faulty or intermittent) the fan will turn on high (uncontrolled).

seanjordan20

I finally found out why the fan comes on at startup. Apparently since the aux pump was a knock off when the car does it's initial check it triggers the fan. Its just like when you install LED side markers and the car does a check at startup the lights flicker. I exchanged the pump with an OEM one and it stopped.

donpb

I'm pretty sure you didn't install that knockoff part, right?

seanjordan20

The brand was right but it was a knock off. They looked exactly the same and around the same price. The Amazon seller got me. Lol. I got the money back so no harm no foul.