Radiator fans not working

Ok gang...having a problem here. 2000 buick lesabre limited. 3800 series motor. Radiator fans aren't working. Relays and fuses have been changed, along with the 190° thermostat and temperature control sensor directly below thermostat......dont Know Where to go from here....seriously stumped. Just replaced the dual fan unit and tested the old unit. One fan was bad.....anyone have any ideas?

YOUR SAYING THE IS POWER TO BOTH FANS???CORRECT?

IS IT GOING TO A GROUND VIA THE TEN/FAN SENSORS?

If you do not have a schematic, here is one for a Reatta and it should be similar....

Sorry....schematic above is not what I intended to post...this is better

Js08016 recommendation is the real deal. This person really knows what they’re talking about. Thanks a lot JS

Je08016... I’m having the same issue for my 2004 Buick Regal both fan are working for low and medium speed but the high speed fan won’t come on when the engine is hot. However, the high speed fan will come on when I turn on my AC. I replaced the 5pins & 4pins relay as well as thermometer & Collings sensor. The coolant was boiling & spilling out of the reservoir tank when the temp gauge is at 3/4 mark

I followed the advice of JS08016-Pinpointed the problem and fixed it and change the temperature sensor. Everything works perfectly. I strongly advise anyone with this problem to start with that recommendation for repair. It’s spot on

Scott... I follow JS08016 instructions but it didn’t work form me. I think the next step for me is to replace the radiator because I don’t believe that there is a problem w the pcm