ECT bad?

So my temp seems to have taken a poop. So I check the fans to make sure they are working, and I have problems.

I run the fan test in the tech section. both relays were tested and both work. the fan turns on for 2 seconds when you start the car. but not when you turn the key to on.

I let the car idle and actually get ho twithout the fans turning on. I thought my temp gauge was bad but both were reading 250.

I turn the car off unhook the ECT harness jumper them and both fans work.

I not quite sure how to test the ECT since it didnt really explain if you test the resistance between both wires or just the one and a ground or something.

To me this shows since I by passed the ECT either the ect is bad or it is covered up with crap or something. the ECT is about 6 months old and is from napa.

what do you think?

thanks

Measure ECT resistance between the 2 pins on the ECT. There is info here (I think) and at TF about resistance vs. temp for the ECT. If you cant find the info, send me an e mail, and I will send you a Excel spreadsheet with the data. I usually remove them and put them in a pan of water on the stove along with a known accurate thermometer and heat the water slowly to monitor resistance vs temp to see if it is in spec.

Any chance the coolant bung on the bottom of the lower intake that points toward the driver wheel well is plugged up (which is pretty common)? This will cause the ECT to read temps way low, and not turn on the fan(s).

anything is possible. The system was flushed last when I did the t3 swap. Ive never put anything in the cooling system, I doubt it but you never know. I will have to check resistance today, make sure it is bad or maybe find tyhe problem.
thank you Jeff

Brian, the other thing that can effect fans is blockage of the fitting on the bottom of the lower intake. This can restrict coolant flow past the ECT so it doesn't see the hottest temps and doesn't signal the need for the fans to be on. Bockage to some degree is common in our cars.

installed my new ford ect after a fight at the dealership with someone who thought they new everything.since the upper intake was off I installed my new braided stainless steel line for the turbo as well. and polished the VC. anyway, I first tested the ford ECT to make sure it worked everything seemed to move right my thermoeter was a couple degrees off but close enough. So i yank the old ECT and started to play with the coolant line under the lower intake. I saw some flow into the hole of the ECT so I tested the old ECT, napa just lost a notch in my book there 4 month old ECT was shot. at 120 degrees it was reading around 40,000 ohms and then jumped to around 7 K ohms at 212 degrees F which the resistance should be around 2.02 so it was bad.

The crappy part is this fan problem stopped my from going to ATCO tonight ergggg sorry Steve.

But it is fixed with my 45 dollar ford part.

Pete thanks for the ECT test.