Circuit for fuse # 74?
 

Hey guys, the X was dead this morning. It appears that something is causing the circuit of fuse #74 to remain powered up. Since my headunit is connected via factory harness, and my air suspension module gets its keyed power signal from the purple/white accessory wire under the center console-----and both only turn off when fuse 74 is yanked---- my question is there any relays or modules that are associated with this circuit/fuse?

I did some digging and found a couple threads about bad "radio modules" but it was unclear as to what they were referencing as some were referencing the location of the amp, and others modules under the battery tray cover. I checked the rear compartments for any water/corroded connectors. Everything checks out visually, leading me to believe its gotta be a bad module or stuck relay somewhere.....any help is appreciated!

From the online WDS: SP0000018714 - WDS (hopefully you're familiar with how to use keyboard shortcuts or your mouse buttons to manipulate the illustration for zooming +/-)

• Telematics Control Unit (TCU) or Universal Electronic Charging & hands-free unit (ULF)
• Voice Input
• Eject Box
• Compensator

Here's a link to Fuse 74 that is one link prior to the one above which lists all of the TIS docs for fuse 74: F74 - BMW WDS

Thanks for the reply. I'll play around with it later tonight!

I've read a few threads about the TCU going bad and causing the drain. Try disconnecting that first, and see if it cures the problem.

Where is it located?

left side of the trunk.

Pop the access hatch and look down. Its the shiny metal rectangle wedged between the floor of the trunk and the shelf where the goodies sit. to disconnect it, you have to raise the floor. the remove 3 10mm plastic nuts holding the plastic floor trim down. then it removes with two mroe 10mm plastic nuts.

The only module down there is the amp for the factory system?

HOLY MOLY THAT WAS A PAIN IN THE ASS!!!!

So I was studying wiring diagrams out the a$$ today. Finally, after tracing wires, tearing out the front seats and console.....it turns out that the 18-pin harness that runs up the console as the pre-wire for the telephone shit had ALL the wires rubbed bare and they were shorting out on each other right behind (or rather inside) the hinges of the arm rest. After ousting that junk, we're golden! I COULD order another harness, but as everything runs through my headunit I'm not going to bother.

As this happened simply as a result of everyday wear and tear, hopefully others will find this helpful in the future!

S.

Glad you found the culprit. Sounds like the wiring harness that runs up to the eject-box for the old BMW installed phones.

Yes sir! Exactly what it was. Thanks again for those diagrams!

Any chance you can be a little more specific about where the expose wires were? I'm chasing an electrical drain as well and that would really help. Which end of the armrest should I take apart first?

Thanks for your help.


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i found the led bulbs with resistors did me in on my x. could be your final stage resistor if it is keeping the blower on. you need to get that voltage tool that measures a draw and start pulling fuses that pertain to it. one of my friends also had his ipod hooked up allnight and that charged throughout the night and drained the battery. could also be the voltage regulator in your alternator. thats just a couple of things to look at

If you open up the armrest, running up the inside of the two visible arms are wires for the BMW telephone. Mine were all broken right where they bend.....BUT I was also intermittently blowing fuses in the rear fuse panel. (As the wires would rub and short, they would blow the fuses in the rear) Only after a while of this (and apparently some chance) when a wire that was "hot" with the key off shorted onto the purple accessory wire did it cause the massive drain I experienced.

One of the tell-tale symptoms of this whole fiasco would be if your MID stays powered up when the key is off and out. I don't see any harm in pulling that harness as a preventative measure for future....but if you don't have the symptoms I detailed, it would probably be best to start looking for a drain elsewhere.

Just wanted to say thank you to those who partecipated at this thread. Fuse 74 kept blowing trough the last couple of weeks on my 2006 3.0i X5 (not immediately.... on a random base) causing the bluetooth phone function to stop working.

I was thinking of the phone module first...but then I came across this thread. Checked the cables that come up to the armrest for phone preparation (no phone physically installed) and the wires were shortening.

Unplugging the harness from under the park brake seems to be quite difficult if not impossible without removing the drivers seat to gain access. As the cable is obviously damaged and there is no purpose for it (at least for me), I just decided to cut it under the storage box, which can be taken out without removing any screw.

I have been reading trough this forum since years and have always taken a lot of benefit from it when working on my X. This time i finally decided to say thank you...