Why did Mercedez change the two electric fans in the front? I have a 2003 ML350 6 cylinders with the two fans, plus the engine fan it never overheats

I have the same SUV and I eliminated the fan and placed a double fan in the front from ( Ml350) and run the wires to the fuse box with a fuse tap and Problems solved. It turns off and on when the car is running. Place a fuse tap to all the wires you added . Just in case.

Excellent job, thanks man!

The control fsm module bypass it

Hi, the red wire, you cleaned the end of, is a power supply to the main fuse box. Power supply to the big fan is another thick read wire with a big plastic nut. This nut is holding a 100 amp fuse for the fan. There may be corrosion to either side of this fuse. The plastic nut gets brittle over tome as well. Ground wire for this fan is screwed to the car body with a 10 mm nut under the right side headlight (driver side in your case) - worth of checking as well. The video clearly shows that fan went to full speed when you actually bypassed the fuse. I would check the fuse. I own an ML 270 cdi with the same fan and I have had similar problems with it.

I have the same fan. Mine was running all the time at medium speed, even on a cold engine. Now it has stopped and doesn't run at all anymore. Main power is good, the controller plug reads 11 volts. Any ideas?

You got more issues than that. That belt for one is so shot. probably tensioner and waterpump as well.