Need Help!
 

2001 Automatic
overheating slowly...fans running real weak
I have replaced the radiator, water pump, thermostat, reservoir tank cap and radiator hoses......I have also checked the fan motors connecting them directly to the battery and they run real strong....any ideas ? any help would be appreciated.....does the ECT have anything to do with this problem??

Did you burp the system properly to get all the air out? You also say the fans run weak, and strong, but are they coming on when they should?
How high is the running temp getting to?
And yes, the ECM does control when the fans come on.

What temps are you seeing?

The fans run in a series/parallel configuration. When coolant temp reaches 226°f, the low speed (series wired) fans are commanded on. They will also turn on if a/c is on at speeds below 35mph. The fans will turn off when temp cools to 219°.

If low speed fan operation isn't sufficient and coolant temp continues to rise, the fans will switch to high speed (parallel wired) mode at 235°f.

Even at 235°, it is not overheating (Though it is unusual for the coolant temp to exceed that).

:cert:

Make sure you are getting air through the fins of the radiator. If it isn't clear or is partially clogged, it WILL overheat. Trust me.