2001 323it, cooling fan not coming on

[thatguy2]

Help my 2001 323 overheats when sitting still for more then 5 min, I figured out my cooling fan is not turning on. I am trying to find the relevant trouble shooting diagram or common fixes so I can start fighting it does any one have any good source?

[MarcoZandrini]

Here’s the link to the wiring diagrams: https://bmwteka.com/wds/en/e46

Now, the electric fan is controlled by the engine computer (DME in BMWspeak). The DME uses a variety of sensors to determine when to activate the fan. The first step is to pop the hood and start the engine while observing the fan. The DME is supposed to activate the fan at 20% speed for a few seconds at each start up. If it doesn’t, the first thing to check is the fuse. The fan fuse is #37, a 50 amp fuse. Pull it and use an ohmmeter to check it. If it’s good you need to pull the large connector at the fan to see if it has power. Use a digital volt meter. The connector has 3 wires. The 2 large wires are power and ground. The 3rd wire is used by the DME to control the fan. The DME uses pulse width modulation to control the fan speed. The fan has power at all times even when the car is shut off. Check the voltage at the proper pin using the engine as ground. Next, switch the meter to ohms to check the ground. You can’t check the signal on the 3rd wire unless you have an oscilloscope!

[Sapote]

Help my 2001 323 overheats when sitting still for more then 5 min, I figured out my cooling fan is not turning on. I am trying to find the relevant trouble shooting diagram or common fixes so I can start fighting it does any one have any good source?

At operating temperature, grasp the rad lower hose to feel if it is hot; if not hot the fan won’t run.

[E39 Newbie]

IIRC, the fan also runs whenever the A/C is engaged. Turn on the A/C. Does the fan turn on?