How to get horn working - aftermarket

donutholer

Regular Member
Joined
Jun 18, 2025
Points
18
Hi,

I replaced my m sport steering wheel with an aftermarket steering wheel. The horn previously didn’t work, I’m wondering which connection it is to get it working:
IMG_1392.jpeg
IMG_1393.jpeg


the airbag wasn’t plugged in on the m sport I realized after taking it out, but no airbag light. The previous owner removed the door cards as well so maybe they did something so the airbag light doesn’t go off. Electrically this car is a mess.
 

Pond

Zorg Guru (III)
British Zeds
Joined
Dec 26, 2016
Points
144
Location
Spaldingski, Lincs
Model of Z
Z3 project
The horn wiring (live and earth) are the two brown ones (the live is red and brown IIRC) in the steering wheel airbag connector which connects to the slip ring on the column..
 

donutholer

Regular Member
Joined
Jun 18, 2025
Points
18
The horn wiring (live and earth) are the two brown ones (the live is red and brown IIRC) in the steering wheel airbag connector which connects to the slip ring on the column..
Don’t think the after market steering wheel has a slip ring, only OEM
 

SV8Predator

Zorg Guru (II)
Joined
Apr 7, 2018
Points
124
Model of Z
Z4 E89 2.0 Atacama Yellow / Z3 3.0 Topaz Blue
Don’t think the after market steering wheel has a slip ring, only OEM
Well, using the wiring info that Pondy has given you, work out out how the aftermarket horn mechanism works? :bored:
 

Mint

Zorg Expert (I)
Supporter
British Zeds
East Anglian Crew
Joined
Sep 23, 2012
Points
222
Location
Stafford
Model of Z
2.2 Sport Individual
Here's the wiring diagram to help. @Pond was right the BR/RT [Brown with Red Trace] wire goes to the coil on the relay, the brown is earth.


Horn Wiring.JPG
 

Pond

Zorg Guru (III)
British Zeds
Joined
Dec 26, 2016
Points
144
Location
Spaldingski, Lincs
Model of Z
Z3 project
Don’t think the after market steering wheel has a slip ring, only OEM
If you don't use a slip ring, how do you stop the horn wiring tying itself in knots? Slip ring also has a tab for cancelling the indicators.

I have an aftermarket boss adapter and steering wheel. The BMW slip ring is fixed to the rear of the aftermarket boss (although it doesn't fit very well when delivered).
 

donutholer

Regular Member
Joined
Jun 18, 2025
Points
18
If you don't use a slip ring, how do you stop the horn wiring tying itself in knots? Slip ring also has a tab for cancelling the indicators.

I have an aftermarket boss adapter and steering wheel. The BMW slip ring is fixed to the rear of the aftermarket boss (although it doesn't fit very well when delivered).
You’re absolutely right, I got this information from another post I was reading on how to install a sparco steering wheel and I believe it mentioned removing the slip ring. Looking at the REALOEM diagram, I believe the slip ring is shared and still attached. I do see the red/brown wire, how do you connect these to the horn? Can I buy the other end of the connector and solder it to the aftermarket horn? I’m just confused as I don’t have something to reference, my horn wasn’t plugged in when I opened the wheel. Thanks for taking the time to respond Pond
 
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