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2004 X3 cooling fan won't come on

13373 Views 14 Replies 3 Participants Last post by  swampX3
Hi there, new member here and looking for some advice . My 2004 x3 cooling fan won't come on regardless of engine temp or when the ac is on either . It's does have power at the 3 pin main harness plug to the fan and ground at the other heavy wire. I came to the conclusion that is was the fan itself from everything I've read on here so I replaced the fan. Well it still isn't coming on ! I've checked all the fuses that seem related to the fan other than the one they say is in the rear compartment fuse block...which I can't locate. Maybe someone could tell me where that is too. I'm at a loss with this thing and just looking for some help. I've read most every post already on this topic but a lot of them didn't go anywhere. Thanks in advance for any tips on what could cause this or if there is a sensor or something i could test. Thanks !
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I wouldn't worry about finding a fuse in the rear compartment if you have been able to confirm 12V at the connector.

Surely it's the low voltage signal from the temp. sensor and the A/C that is the problem. As you probably read, the integrated switch in the fan is the most likely failure point.

No personal experience, but from other posts it sounds like it is critical to buy a replacement fan from a vendor that needs your VIN to confirm the correct unit is supplied.

Model year doesn't seem to be enough. Presumably because of differences in the fan switch for AT vs. MT, manual AC vs. auto climate control, etc.

As you observed, previous threads did not close the loop on how they tested sensors or how they eventually solved their problem.
FESTCHIVE fan links

looks like your big fuse 73 or similar is OK ing power .....view, study and inwardly digest these learnings .....get some DIS57 or Rheingold software so you're not working blind and can activate stuff from your laptop

are you getting "command on" for the fan from the ECU (engine computer).....see post 17
using simple laptop software to test a coolant fan etc /get fault codes
Thanks for the advice on testing the motor. I don't have a pulse generator though. If there is a code stored for the fan not starting does that need to be cleared in order for it to work after replacing the fan ? Also can you activate the fan if you have a proper scan tool ? Thanks !
testing coolant fan etc

no absolute need to clear any codes in this and most cases except for situations when engine power and transmission settings are specifically adjusted way down by the computers

I included the pulse generator test to illustrate how your computer does its job .....and .....real fixes real fast video shows how we figure out if we are getting the essential signal from the computer to the fan electronics

you can activate the fan for a simple functional test that is very easy to do using using DIS57, INPA,Rhiengold etc ....about 80 bucks to buy the cable and software or the software can be downloaded from the internet if you have a basic computer/laptop skills ....just buy the cable on its own if you choose that route

I don't know why folks spend a bunch on small code readers when they have have nearly factory functionality downloaded on their laptops for very low's a quantum leap in DIY ability and diagnostics....go for it !

did you test the fan temp switch and get an ok output ????

do you have the aircon switched on ????
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do a quicky fan switch test

chopped this link out of your thread for speed

let us know how you come out with this fan switch test.....not on an X but very generic for BMW and millions of others
I did have have the ac switched on as well and the fan didn't come on. I haven't done the fan switch test. Is that the one in the lower radiator hose ? Thanks !
fan switch in lower radiator hose

yes ...many are in the lower hose ....check it / jump it ASAP

the switch on a 2004 X3 M54 engine is part number 4 in this link.....put the last seven of your VIN into REALOEM.COM and verify the correct one for your vehicle
Thanks a lot for the link. I'll try the jumper wire test on it tomorrow. Should there be power to one terminal with the key on ?
more good links for your coolant temperature switch test

view, study and inwardly digest these links ....they will help you understand testing the coolant temp switch but also form the basis of many other switch etc tests wishes

heres a running start from scanner danner

This same test can be followed for both 2 and 3 wire coolant temp. sensors and applies to ALL cars, not just the one in this video (Hyundai Santa Fe)
For more information on this topic, I have written a "field manual" called Engine Performance Diagnostics which is available at as an eBook or paper book.

this one shows the basic OBD etc codes for various failures and using a very low cost meter to test sensors

more good references
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I got the fan fixed. It was the signal wire at the main plug for the fan. I tugged on it and it pulled right out of the connector. The insulation was intact but the wire inside was green and disintegrated. Ran a new wire and the fan works as it is supposed to now. Thanks for all the input ! Guess it's always good to check the simple things before replacing expensive parts !
great find !

well done ....a great fix ....bust wiring can be tough to find....the smaller thermal imaging cameras at reasonable diy'er cost have been a great help to us finding bad wiring/relays etc....see the experience below....get one for your birthday

best wishes

FESTCHIVE on thermal imaging experience
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