[Thebimmer57]

Please tell me what this wire is from I tried looking for the connection but cant figure it out, the car still cranks. Thank you .

[IllSic_Design]

How about a less zoomed in picture or where the wire is located?

[porsche959]

is that going to the maf sensor?

[Antetokounmpo]

there's only about 83 different purple wires on these cars...

[bluewater328]

Looks like the MAF wire. You're running off MAP now which is why it still cranks.

[GoRomeo]

Any CEL on dashboard?

[ckanderson]

hey guys here's a photo of a random broken wire and my fingers. why does my car still start?

[6ixSpd]

Originally Posted by ckanderson

hey guys here's a photo of a random broken wire and my fingers. why does my car still start?

E90Post Class of 2020. Every year, the rabbit hole gets deeper and dumber, lol.

[feuer]

How can one accidentally ripped that wire? Probably took a yank of decent amount.....

[PhaseP]

It is not the MAF, MAF has more than one single wire.
From the vicinity it could be the wire that goes to alternator from the ECU. How ECU controls the alternator output voltage. With it disconnected alternator defaults to a set voltage output and everything will still run.

Edit: Just checked Bentley, that most probably is that alternator wire I mentioned. Because books says it is "Violet" color (up to 03/2007 production which covers OP's)

[Thebimmer57]

@PhaseP Yes I think you are right, the wire came from that area, and I yanked it out because I was pulling out some of my shredded serpentine belt that id seen while trying to find a bolt I dropped and didnt realize there was a wire there, it was also pretty dark out and I was putting the last finishing touches on my Rev9 adjustable coilover kit. but hopefully this pic can make this definite, Its definetly not the maf wire but if its from the alternator it sucks cuz I just had this one put in a month ago lol, oh well thanks for the responses!

[PhaseP]

In the mean time don't let that touch any metal to be grounded. That wire is actually same BDS (Bit Data Stream) line/bus that oil level sensor, water pump and IBS (intelligent battery sensor) are all connected and share. I suggest tape it off the bare copper strands and secure it somewhere there, maybe tie it or tape wrap to the MAF wire, for the time being.
You don't need to remove the alternator to fix this. You just need to remove the air intake tube and maybe the air box to access the alternator to remove the other end of the wire and connector. Then some wire repair will be needed either soldering or crimping. If soldering cover it with heat shrink tube that has built in glue that seals it against moisture.

[Thebimmer57]

Thank you @phasep, Ill tape it up for the time being and attempt to secure it back to the alternator tomorrow, I will be driving from NY to FL in a week, so do you think this will hold up, ive been driving the car vigeriously since I ripped the wire and everything seems fine, thank you again for the extremely helpful responses.

[PhaseP]

I have not experienced or tried this myself first hand but here on this forum people reported that when that wire is disconnected from the alternator, the alternator goes into default mode and maintains a default charge volt, something like 14.5V if my memory is correct.

I would check the alternator voltage with a voltmeter as engine is running to verify this. Otherwise you maybe using battery charge and eventually engine will shut off once battery drains. The ECU is supposed to warn you when alternator is not supplying charge to battery, but at least with my car it didn't warn me one time, and car shut down while commuting back to home. Not sure why and still don't understand how come ECU didn't warn about it while using battery charge all the while.

You can check the alternator/battery voltage via OBC hidden menu too.
See here:
http://e90.wikifoundry.com/page/BC+hidden+menus
It is menu 9 UB.

[PhaseP]

Also this may be your bigger worry:

...I was pulling out some of my shredded serpentine belt …

Hope some of them didn't end up going into the engine. There are stories of those which then clog up the oil pickup screen causing oil starvation.
How long has it been since the belt was shredded?
You should judge for yourself if it is risky or not to take a long travel.

[Thebimmer57]

Thanks for responses and yeah the alternator/car is operating as it should for now since I first made the post, and the serpentine belt issue has been dealt with i also checked to see if the seals were broken or has belt in, and I think its good(Lol weel see). Since that I also put in a full coilover suspension and am installing sway bar links for the front and rear, the back is clunkning slightly but all that will be handled tomorrow.

[jbucky1]

Hi Phase P, the link has expired, pls could you tell me the way to get to the hidden menus. Thanks PhaseP

Originally Posted by PhaseP

I have not experienced or tried this myself first hand but here on this forum people reported that when that wire is disconnected from the alternator, the alternator goes into default mode and maintains a default charge volt, something like 14.5V if my memory is correct.

I would check the alternator voltage with a voltmeter as engine is running to verify this. Otherwise you maybe using battery charge and eventually engine will shut off once battery drains. The ECU is supposed to warn you when alternator is not supplying charge to battery, but at least with my car it didn't warn me one time, and car shut down while commuting back to home. Not sure why and still don't understand how come ECU didn't warn about it while using battery charge all the while.

You can check the alternator/battery voltage via OBC hidden menu too.
See here:
http://e90.wikifoundry.com/page/BC+hidden+menus
It is menu 9 UB.

[jbucky1]

Also, kinda rookie question here... the Purple alternator sensing wire.... is it on the Engine Harness / engine / Transmission / all ?

Im trying to figure out how to replace the wire on mine, its broke on the harness but I'm struggling to identify the specific harness it is on. , since there are quite a few engine harnesses (injector / glow / sensor)

[PhaseP]

Google "OBC hidden menu e90" you will find lots of references for hidden menu.

About harness, I don't remember, sorry. You can check the pictures posted in the thread to try to figure out that.