R170 SLK230 Radiator Fan problem

[Waldi]

Hi, my R170 (SLK230) 1998 started overheating.
I replaced the cooling fan module and the complete fan but still did not solve the problem. BTW the radiator icon on the dash is off when the car is still cold but when it heats up it lights up (Think when it reaches the temp where the fan is suppose to kick in). The electric fan runs when I connect it directly to the battery. I have gone through the forum searching for similar problems but I could not find a solution to solve the problem. Could the coolant temperature sensor be defective, are there any fuses to be checked and if so where??. I am hoping that someone in the forum could help me solve this problem.
Thank you