Circuit for fuse # 74?

[X5SND]

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!

[Qsilver7]

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

[X5SND]

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

[jgold47]

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.

[X5SND]

Originally Posted by jgold47

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?

[jgold47]

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.

[X5SND]

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

[X5SND]

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.

[Qsilver7]

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

[X5SND]

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