Originally Posted by
M SL 65
I have have read all the existing posts at least twice. Not meaning to be flippant.
The light is really slow to come on - an eight count.
I have topped up the overflow tank.
I have replaced the overflow tank sensor.
I have remove and flushed out the overflow tank and yes the floating magnetic ball rattles.
I have replaced the temperature sensor.
The fan runs when the car is warmed up.
The fan runs when the A/C is turned on.
I am assuming the coolant module is in tune with the ECU??????
Any help or suggestion would be greatly appreciated. .
It sounds like you've checked everything. The only things I've found that cause this fault are: Faulty Overflow Tank sensor, Faulty Overflow Tank float, Faulty Fan Controller and Blown Fan Controller Fuse. If you've replaced the Overflow Tank Sensor and the Fan runs, then that rules out the Sensor and the Fan fuse. Even though the ball in your overflow tank rattles, it may not float, ie, it could be stuffed (this is a fairly common failure). The fan can also operate while the fan controller is starting to fail, but it usually stops working or ends up blowing the fuse. I'd try a new overflow tank first, then if that doesn't work, replace the fan controller.