Massive parasitic current leak (4 amps!)

[Multibeemer]

As it says in the subject bar, our 03 4.4i has an enormous parasitic current leak.
After having the ground cable disconnected from the negative battery post for several hours, I placed a 10 watt, 1 ohm resistor between the negative battery post, and the cable that was attached to it. The voltage drop across the resistor is about 4 volts, which equates to a 4-amp current flow! I didn't even have to make the measurement to know I have a huge parasitic leak - the resistor got very hot very quickly.

So, before I spend a lot of time pulling one fuse at a time, are there some high-probability candidates for such a huge current draw I should look at? And does anyone have a favorite method for tracking down a parasitic leak? I would think finding one this big shouldn't be too difficult. Thanks.

[SMOKEY53]

Final stage or blower resistor is a good place to start......that, and a search.

[upallnight]

Fan control resistor.

[Multibeemer]

Yes, I just did a search, and the FSR did come up as a likely culprit. Are there any symptoms when the FSR goes bad and starts drawing huge amounts of current when the car is off? For example, does the fan run on its own? Or does is sometimes go bad without giving any symptoms? Is there any way to test it, in other words? Does anyone know offhand which fuse's circuit it's in? I assume if I pull this fuse, and the leak stops, that would be a pretty sure way to confirm the FSR was at fault, right?

Edit: My apologies for not doing a search before posting this question, as there are tons of threads dealing with battery drains on these cars. I found that fuse 64 controls the FSR, and that another common cause of large drains if the Telephone Control Unit (TCU), which is fuse 74. Hopefully, it's one of those.

[SMOKEY53]

No worries, let us know what the final verdict is.

[audiophool]

I had an alternator go bad one time and had a 4A draw. Turned out it was the diode pack.

[Multibeemer]

Thanks for the replies - makes me feel like I'm not alone in this.

No luck so far - I pulled all the fuses people had posted as potentially protecting the blower fan circuit (64, 34, 48, and 9), and I get the same 4 amp draw each time. So, this rules out the FSR. I also pulled fuse 74 (Telephone Control Unit, apparently another common culprit), and same result. And just because they're easy to get to, I pulled each of the fuses in the rear fuse box, one at a time, and got a consistent 4 amp draw each time.

I did all this before opening this thread, so I'll next check the aux radiator fan, but it's getting late, and I haven't had dinner, so this will wait till tomorrow.

If that turns out not to be the cause, I'll take it to an auto parts store to run an alternator test. I'll report back what I find, and in the meantime welcome any other ideas. Thanks.

[electricalserv x5]

Originally Posted by SMOKEY53

Final stage or blower resistor is a good place to start......that, and a search.

RIGHT ON BROTHER,nailed it...............

[electricalserv x5]

Originally Posted by Multibeemer

Thanks for the replies - makes me feel like I'm not alone in this.

No luck so far - I pulled all the fuses people had posted as potentially protecting the blower fan circuit (64, 34, 48, and 9), and I get the same 4 amp draw each time. So, this rules out the FSR. I also pulled fuse 74 (Telephone Control Unit, apparently another common culprit), and same result. And just because they're easy to get to, I pulled each of the fuses in the rear fuse box, one at a time, and got a consistent 4 amp draw each time.

I did all this before opening this thread, so I'll next check the aux radiator fan, but it's getting late, and I haven't had dinner, so this will wait till tomorrow.

If that turns out not to be the cause, I'll take it to an auto parts store to run an alternator test. I'll report back what I find, and in the meantime welcome any other ideas. Thanks.

Its a resistor for the secondary air fan, is the red light on next to your push button and screen or is the fan running with the engine off[ silence for it]

[snbx5]

Had exactly the same prob on my 2004 X5 just over a year ago.
Changed the FSR but no change

It was the BMW genuine ipod connector in the rear compartment and the lead that went to the front for the HU. took ages to find as it was erratic.

We thought it was something to do with the door locks and starting the sat nav up but after they disconnected the lead, it has been fine ever since...well up to the point when I binned the original HU for a Hualingen 5gen + audison voce speakers + sub :-)

HTH