Why do owners come on this forum and ask for DIY advice but are too cheap to buy the equipment to DIY? I have various scanners for the cars that I owned or work on for family. I have a Honda Specific scanner for the my daughter Honda, Toyota software and cable for the Soccer mom minivan and when I owned a BMW I had carsoft 6.5 and later BMW Scanner 1.4. I have a scanner for when I owned an Audi. The only cars I don't have a scanner for is the 911 PORSCHE and the Lotus.

Cool story, Its not a matter of too cheap. I own a fleet of cabs, do 90% of the required work on them myself...Pay for a legitimate toyota TIS professional diognostic subscription to have access to digital tools I need for them, Its also far from being a case of being unwilling to acquire the appropriate tools....

but we are also in the middle of a pandemic that is causing pandemonium with logistics and stocking. I have had things that should be overnighted from a city 4 hours drive away take over a month to arrive....So, Having not needed one up until this point, as stated I was hoping getting my hands on one was not the only way to diagnose a fan issue...I was hoping someone with a more intimate understanding of the X's fan control systems would have a simple "oh yeah, just unplug this...or just bridge that, and the fan will run if its not shagged" instead of potentially waiting weeks just to be able to diagnose it, then weeks again for the correct part to arrive after figuring out what it needs.

In short...sorry for asking a fucking question...your highness.

If you see my post a few above, with the 1, 2, 3 tests I ran on mine, you should be able to definitely run 2 (AC on). If you can find a 100 Ohm resistor, you can do 1. Not 3, since that needs the Foxwell.

And I'll be even more direct than I was in my previous posts here ... Don't believe what you read or see on the intertubes on this. It IS more complex than most think.

If you've got a True RMS voltmeter, you can measure voltage on the control wire.

In my case, doing all the above and a few more allowed me to become fully convinced that the power and signal going to the fan all made sense, and were there. So with the fan not spinning, it only remains to swap in a new fan.

For a still unknown reason, my PA Soft BMW Scanner 1.4 did not run this time. I was going to try installing it from scratch on a different laptop, but at this point, I don't think it would tell me anything new.

And in defense of @upallnight, in exchange for the occasional rough comment like that, he has probably the highest batting average on here for tough problems. I'll take that over friendly wrong answers any day.

Good luck getting this solved.

UPGrayd, a couple of the members here can be annoying for sure but most of us are happy to help fellow X5 enthusiasts any way we can. Just shrug them off.

If I ever doubt my fan is operational, I simply unplug the AC pressure switch shown below with engine running and AC on and the fan will run full song after 5 seconds. This will at least let you know you have an operating fan but may not diagnose your DME controlling it dependant on engine temp. For that you need the cable you have ordered and a copy of INPA installed on a PC. My guess you have a fan out or going out and the quick AC pressure switch test will let you know. Mine is a 3.0L M54 model but I would guess your diesel M57 would have the same AC pressure switch. :dunno:

You're the one that embellish your story with the comment that you were hoping not to have to buy the cable. I just pointed out that fact. If you look at my postings count I'm one of the more active member on this board. I have helped many X5 owner through this board as well as in person. At the very end you go and drop the F bomb. Well add me to the list of people to ignore your posts.

Oh and by the way have a G'Day mate. Don't need to put anything on the barbie for me.

Thanks Oldskewel, for the friendly testimonial.

:thumbup:

Yep, OB, there is an A/C pressure switch in the exact same location on the M57 diesel. Not sure if it has the same "test feature" in the M57 DDE (vs the M54 DME) since I have (and use) INPA to test the aux fan.

Worth a crack though! :thumbup:

Nice to have more info.
My 2001 3.0i looks just like yours, but nowhere near as clean.
I just ran that test on mine, measuring the fan control signal as I have been doing, and confirm it works as you say. :thumbup:

So yes, that is a very easy test. Maybe THE easiest, as long as you know your AC works.

Just turning the AC on should make the fan spin, even if very slowly. Disconnecting that plug should ramp it up to almost full speed within a few seconds.

Specifics on the testing I did:

AC Pressure, as measured in Foxwell (units = Volts):
engine cold, about 70*F ambient.
Ignition ON, engine stopped, AC off, cold: 1.25V
... connector removed: 5.00V
Engine running: 1.24V
Engine running, AC on: 1.76V, rising
... connector removed: 5.00V

When the AC was turned on, the fan control signal dropped to 12 .. 11V, as before.
When the AC pressure sensor connector was removed, it very quickly ramped down, at about one Volt per second, ending at about 2.0V, which should be almost top speed for the fan.

That’s some very helpful information oldskewel


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Thank you mate, My apologies I did miss that reply.

I definitely have no fan with A/C on (the ac going warm when sitting at a set of traffic lights momentarily is what actually drew my attention to the fan in the first place).

I am dealing with a death in the family at the moment, but over the weekend I will try to get my hands on a 100 Ohm resistor and see what I come up with.