72' 510 Horn Wiring / Momo Corse Wheel Assy

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Joined: 13 Feb 2015 09:39

72' 510 Horn Wiring / Momo Corse Wheel Assy

Post by BrianE » 09 Mar 2018 12:52

Looking for guidance in so far as the proper wiring interconnect of a 72' 510 horn to an aftermarket Momo Corse horn button / steering wheel / hub assy.

To be clear, I am a complete newb electrical wise. I do have the colored wiring diagram for the 510 sedan and it seems to align with the horn circuit as I compare the diagram to what I am seeing in the engine compartment and over at the turn indicator/Hi-Lo/Horn connector located on the column. For what it's worth, Fuse box has been given a thorough vinegar bath mid 2017. The following all function properly...., turn indicator, emergency flashers, Hi-Lo lights, Dome light, heater switch, 2 speed wipers and gauges.

Horn is physically mounted on the driver's side

ImageUntitled by Brian H2012_iPhoto, on Flickr

Solid green wire diving into a harness and reappearing at the stock 3 wire (GY, G & B) relay located on the passenger side in front of the fuse box
ImageUntitled by Brian H2012_iPhoto, on Flickr

Upon removing the horn button/steering wheel/hub from the column, I find this.....

ImageUntitled by Brian H2012_iPhoto, on Flickr

Separating the button from the wheel, I find this (note: I disconnected the red wire/spade from the horn button to better show that it appears as if 1 of it's 2 original leads has been cut and removed???.....

ImageUntitled by Brian H2012_iPhoto, on Flickr

So...., recommendations on how to proceed from here would really be greatly appreciated. Thanks!

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Joined: 01 May 2008 22:06

Re: 72' 510 Horn Wiring / Momo Corse Wheel Assy

Post by Tedman » 27 Mar 2018 23:09

Looks like you're missing the curved copper contact spring arm on the turn signal assembly. You can see it in this pic:
The Black/Green wire from the horn relay conducts power to the horn switch through this contact. Been a while since I've seen the inside of a Momo hub adapter, but generally there's a copper or brass ring on the bottom of the hub adapter that rides over the spring arm maintaining constant electrical contact with the spring arm no matter how the wheel is turned. On your red wire, the spade connects to the button like it was before you removed it. The other end with the coil spring connects inside your hub adapter somehow to make contact with the ring which is in contact with the spring arm. So power comes from the horn relay BG wire to the turn signal assembly, through the spring arm, to the hub adapter ring, through your red wire into the button. Pressing the button makes an internal connection from your red wire to the thick steel wire on the side of your horn button which grounds to the steering wheel frame when the button is in place, and your horn honks.

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