Momo steering wheel wiring confusion

[voxboxer]

Hello everyone,

I’m restoring my first Porsche, a ’68 912. I installed new front and rear harnesses and the wiring has been pretty smooth so far. My last obstacle is the MOMO steering wheel install/wiring. I’ve read a bunch of wiring threads on Pelican and still have unanswered questions, mainly because there’s not a lot of posts about the 1st generation Porsche 911s/912s.

I have two wires coming through the column… a brown/white and a brown ground wire. The other end of the brown ground wire routes through the wiper switch controls and grounds on the body under the dash. The wiring diagram shows the brown/white wire going directly to the horn relay. I assume that goes directly on the horn button and the ground wire to the contact plate?

But as you can see in the pic, I have THREE connecting tabs…
1. The back of the contact plate
2. The back of the horn button
3. In the cavity of the steering wheel itself.

Could someone tell me which wire goes where? Additionally, how do they route through the steering wheel adapter when the only hole I see is the what goes directly on the steering shaft?

Thanks in advance for all your help!

Jeff

[Saadi996tt]

Hi Jeff,

I just installed mine in a 77s which may differ from your car. I hooked up the Brown (ground) wire to #3 and the brown and white (power) to #2 my horn would blare so I figured that the ground and power were completing a circuit without pressing the horn button. I then hooked up the brown to #1 and brown and white to #2 and it worked properly. I didn’t have anything hooked up #3 but I did use a momo hub so I don’t know if that makes a difference for your car. Hope that helps…

Thanks,
Saadi


Sent from my iPhone using Tapatalk

[themedulla]

I just went through this with my '72.

The brown/white is the switched (hot) line. If it in any way connects to ground your horn will go (assuming that your horn relay and horn are functional). This needs to connect to the copper contact plate. On the Momo hub there is a plunger that runs along the contact plate and a wire inside the hub that runs up to the horn button.

The brown ground wire is redundant (I think) and doesn't need to go anywhere. The body is ground. The Momo button and hub connect the switched line to the ground through the body when the button is depressed.

Be careful to place the wires carefully when you install the wheel. It is possible to pinch the brown and white wire causing intermittent and unpredictable contact with ground. Ask me how I know.

If you aren't using a Momo hub then you've got a setup I'm not familiar with. If Momo makes a wheel that uses only the steering wheel nut I'm not aware of it. In any setup that doesn't use the Momo hub I would assume the brown/white switched wire goes directly to the horn button and the connection to ground is made through the body ground - especially since your horn button only has one spade lug.

[themedulla]

I just looked at your pictures a bit more. The connection marked #3 I do not believe is necessary. On my horn button I had two lugs. Momo supplied a short jumper wire that went from the lug #3 in your picture to the ground lug on my horn button.

On your horn button there appears to be a metal ring that makes the connection with ground.

Also, no wires need to pass through the hub. The plunger on the hub should provide a wire inside the hub. The ground connects through the body. This will mean that your brown ground wire is just hanging out inside the steering column dangling around making you nervous.

[HarryD]

These threads may be helpful.

https://forums.pelicanparts.com/porsche-911-technical-forum/1164947-horn-issue-85-911-a.html

https://forums.pelicanparts.com/porsche-911-technical-forum/138526-idiots-guide-momo-prototipo-install-carrera.html

[voxboxer]

Thanks for your help, guys.

HarryD, I found those threads but they didn't clear everything up with my set up.

themedulla, thanks for all the info. I will give everything a try and let you know.

[HarryD]

Originally Posted by voxboxer

Thanks for your help, guys.

HarryD, I found those threads but they didn't clear everything up with my set up.

themedulla, thanks for all the info. I will give everything a try and let you know.

Lets try this thread. https://forums.pelicanparts.com/porsche-911-technical-forum/1158595-officially-confused-momo-horn-wiring.html

Looking at the wiring diagram, the brown and white stripe wire goes to your contact ring (#1 in your picture). The brown one, connects somewhere in the column to ground everything and the wire goes there.

The adapter has a contact pin that contacts the contact ring, the wire in the adapter from the contact pin is connected to #2 in your picture. When you put the horn button on the steering wheel with the silver adapter (#3 in your picture), the button ground is the v shaped spring which contacts the steering wheel. for your path to ground.