[kniffs]

Hey!

I have a 2018 model 440i GC LCI MPPSK

Installing paddle shifters, i accidentally shorted the signal horn by rotating ground cable making it touch retainer plate. Horn went off for 1-2 minutes straight and then silence, after this horn has been quiet (2 months ago)

Everything works except horn (i have the correct harness for heating, lane departure)

Troubleshooting:

1) I repositioned horn ground so it's in correct position.

2) I checked for burned 15A (blue) fuse in FEM located in passenger footwell, however LCI models does not have a horn fuse.

3) I bought bimmerlink to read codes - no active codes, two stored codes from when error happened. See picture attached.

Could i have burned a relay, or the horns themselves? Is there maybe a "horn reset" or horn adaptation function to reset short circuitry in ISTA?
I know it exists for lamps and bulbs, but i have not heard about signal horn.

Appreciate any ideas or help!

error i made, shorting signal horn with ground cable rotated touching airbag retainer plate


No 15A horn fuse in FEM fuse box


Inactive codes from when error happened

[AlmondJayRoM3]

No fuse and no external relay. Only possible components that could have failed are the steering column switch cluster(module or the actual switch for the horn), FEM, or interconnected wiring. Your symptoms and error codes show its probably not the FEM or the associated LIN bus line. Check for a short to ground at the horn switch/button that leads into the steering column switch cluster module. If it is not physically shorted or stuck, then the problem is internal to the steering column switch cluster module and that would need to be replaced.

EDIT: Forgot to add, did you try clearing the codes?

[kniffs]

Originally Posted by AlmondJayRoM3

No fuse and no external relay. Only possible components that could have failed are the steering column switch cluster(module or the actual switch for the horn), FEM, or interconnected wiring. Your symptoms and error codes show its probably not the FEM or the associated LIN bus line. Check for a short to ground at the horn switch/button that leads into the steering column switch cluster module. If it is not physically shorted or stuck, then the problem is internal to the steering column switch cluster module and that would need to be replaced.

EDIT: Forgot to add, did you try clearing the codes?

Hi and thanks for the response. As i showed in one of the pictures, the short was caused by myself by accidentally connecting a wire to ground, which i then fixed. Problem is after fixing it, the horn still does not function.

Yep i did try to reset stored codes!

My current belief is that short circuit protection in the FEM/FRM has triggered, and needs to be reset. Appearantly there is short circuit protection when a lamp or others have reached 50 or higher errors. There are many guides to do this for lamps or similar with Tool32, and is also included in Bimmerlink - but i have not found details for horn/trumpet/fanfare

[Billfitz]

An OBD diagnostic tool that will find the short circuit fault code should be able to clear it. But your scan doesn't show that. You could have burned out the horns, it's easy enough to test them with a direct connection to the battery charging posts. They fail all the time from even normal use, let alone what you did. It should be needless to say but never remove the wheel without disconnecting the battery negative terminal.You're lucky that you didn't trigger an air bag fault.

[kniffs]

Originally Posted by Billfitz

An OBD diagnostic tool that will find the short circuit fault code should be able to clear it. But your scan doesn't show that. You could have burned out the horns, it's easy enough to test them with a direct connection to the battery charging posts. They fail all the time from even normal use, let alone what you did. It should be needless to say but never remove the wheel without disconnecting the battery negative terminal.You're lucky that you didn't trigger an air bag fault.

Thanks for the reply. Battery was disconnected during the procedure, it was when reassembling I missed that the cable Shoe for the horn was rotated and touching the retainer plate, so when i went to reconnect the negative terminal on the battery the horn went crazy as if I was holding it down, then it went quiet.

[MidtownMike]

Did you try to connect the horn directly to 12V to check of the hardware is still ok? The horn is not designed to go for 1-2 min without pause and it may just have overheated and died. Happens a lot during Middle Eastern weddings when the wedding party drive around a train of rental luxury cars and continuously honk and rev to attract attention.

[kniffs]

Originally Posted by MidtownMike

Did you try to connect the horn directly to 12V to check of the hardware is still ok? The horn is not designed to go for 1-2 min without pause and it may just have overheated and died. Happens a lot during Middle Eastern weddings when the wedding party drive around a train of rental luxury cars and continuously honk and rev to attract attention.

I will give it a whirl, thanks for everyones inputs! You live and you learn

[toxik]

Originally Posted by MidtownMike

Did you try to connect the horn directly to 12V to check of the hardware is still ok? The horn is not designed to go for 1-2 min without pause and it may just have overheated and died. Happens a lot during Middle Eastern weddings when the wedding party drive around a train of rental luxury cars and continuously honk and rev to attract attention.

F30 horns seem to be crap even from factory, I've read a ton of people on here having to replace one after it dying for no reason.

[aardate]

Originally Posted by MidtownMike

Did you try to connect the horn directly to 12V to check of the hardware is still ok? The horn is not designed to go for 1-2 min without pause and it may just have overheated and died. Happens a lot during Middle Eastern weddings when the wedding party drive around a train of rental luxury cars and continuously honk and rev to attract attention.

That actually happened at my brother's wedding LOL

[YASBBYM3]

Anything that has voltage running through it and is OEM from factory WILL run throw a fuse. Period.

[MidtownMike]

Originally Posted by YASBBYM3

Anything that has voltage running through it and is OEM from factory WILL run throw a fuse. Period.

It probably does run via a fuse, but according to F30 fuse diagram, that fuse is not in the main fuse box and is not meant to be serviced by the user (like many items in F30).

[AlmondJayRoM3]

Originally Posted by YASBBYM3

Anything that has voltage running through it and is OEM from factory WILL run throw a fuse. Period.

Correct. But in this case only the FEM is fused and not a specific fuse for the horn circuit.

[AlmondJayRoM3]

Originally Posted by kniffs

Hi and thanks for the response. As i showed in one of the pictures, the short was caused by myself by accidentally connecting a wire to ground, which i then fixed. Problem is after fixing it, the horn still does not function.

Yep i did try to reset stored codes!

My current belief is that short circuit protection in the FEM/FRM has triggered, and needs to be reset. Appearantly there is short circuit protection when a lamp or others have reached 50 or higher errors. There are many guides to do this for lamps or similar with Tool32, and is also included in Bimmerlink - but i have not found details for horn/trumpet/fanfare

If you've eliminated the possibility that the horn button is shorted, you need someone with a scan tool to check if the steering column switch cluster is permanently requesting a horn. If that's the case, the module needs to be replaced.

[kniffs]

To reiterate, F3X does has a individual horn fuse up until LCI,15A and sits in the FEM module. Considering how common horn faults are/were on F3X, i suppose BMW changed how things work with the LCI

Originally Posted by AlmondJayRoM3

If you've eliminated the possibility that the horn button is shorted, you need someone with a scan tool to check if the steering column switch cluster is permanently requesting a horn. If that's the case, the module needs to be replaced.

Thanks, i feel i've messed up enough on this one so i'm taking it to the stealership in two weeks!