Radiator fan doesn't start randomly. New fan didn't solve.

What BSI?

Sorry my mistake. The BSM. That's the fusebox in the engine bay.

Fuses are first thing I checked. No problem there.

In the grey connector on the fan assembly.
Pin1. fan speed signal from engine ECU.
Pin2. "Faulty" signal from fan controller to engine ECU.
Pin3. Not sure, but I think this is a fan controller enable from the BSM.

The black connector on the fan assembly.
Pin1. Main power from battery through Maxifuse MF1 under the BSM.
Pin2. Earth to chassis and battery return.
Check for corrosion on the connector pins of the engine ECU. Check for corrosion on the connector pins of the grey connector of the BSM. Your BSM might not be the same as the one in the picture but you can still check all the connectors for corrosion.

Checked all those, absolutely no corrosion. I sprayed dry contact cleaner anyway. Then tried the car, fan started at exactly 97 C.
Then after stopping the car the wheel servo didn’t start, I checked and cleaned all fuses, started again, no servo. Tried to move the car, servo started after 20 meters.
I’ll see what happens in the next days.

chriz74 wrote: ↑Mon Aug 24, 2020 6:50 pm Then tried the car, fan started at exactly 97 C.

Sounds fine. Mine starts at 96, runs at medium speed until the temperature is 95 and then cuts out.