Jws1

Hi all,
sorry had a look to see if anyone else has my issue.

Have a coolant level warning on the dash, level ok so changed the level sensor, still no resolve. Noticed the large red wire to the fan broken fixed this and still have the warning and now the fan runs all the time regardless of engine temp.
what should I be checking and is where is the fan switch.

2005 clk320

thanks in advance