Radiator fan is not working properly

MICHELLERENEEMYRES

MEMBER
2008 BMW 328XI
6 CYL
4WD
AUTOMATIC
93,000 MILES

My radiator fan isn’t kicking on, only kicks on if I have the engine coolant temperature sensor disconnected. I’ve change the engine coolant temperature sensor I’ve change the radiator fan sensor switch I’ve change the oil engine sensor. I have put on a new serpentine belt and a pulley 2 expansion tanks, air mass flow sensor, transmission fluid, final stage resistor, and evap canister. The actuator motor. A new thermostat and a new water pump. The housing oil gasket, and some more stuff. I just can’t think right now. I have been worn down from trying to figure this out and not be more go anywhere in like six months. Please someone help me.

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1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

If you unplug the coolant temperature sensor and the fans come on you know the circuit is good. So, I have a feeling there is power lost to the relay. If you want, here is a link that explains how to test a relay.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

You have already done a lot. I just noticed you didn't mention the relay or fuses.

I attached two pics below showing the entire wiring schematic for the fans. I highlighted the power supply. Realizing the fan turns on when you disconnect the sensor, I don't see a problem with the HD fuses. It's the 5 amp fuse (number 28) under the dash on the right side.

Check the fuses indicated. In addition to checking the fuses, make sure there is power to and from them. Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Let me know.

Take care,

Joe

See pics below.

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