M880 Horn only works part time?

[8dogsbarking]

It is the strangest thing, I just converted my '77 M880 to power steering, and in the process I replaced the grounding strap. Now that I have done all this, I can only get my horn to work when I have the steering wheel in a certain position. After I found out my horn was on the fritz, I took my steering wheel off to take a look at the contact. I sanded down the horn ring and cleaned it before putting my steering wheel back on. It appeared that there was a copper film on the ring at one point, but where the wheel makes contact with the ring, it was worn away. Do I need to apply some dielectric grease to the ring to make it work? Is there something wrong with my contact wheel or something? Any advice would be appreciated. ALSO, where should one go to find black out light mounts? I have the lights (cut off by a rural FD) and would like to put them back on now that I have repaired all the wiring glitches.

 

[N1265]

I doubt you can get just the mount for the blackout lights ( cat eyes ) you will probably have to find another truck for parts.

Horn: no copper = no contact. you probably need new parts. grease is usually for coroson protection and the horn should work without it.

if the horn was working right before you changed the ground strap I would double check and make sure the problem isn't there...

 

[8dogsbarking]

So Strange, drive shaft wont ground

Well, after months of working on the problem, I have found out why my horn isn't working. It seems that the drive shaft, at the ujoint, isn't grounding. It works when a wire is connected between the horn contact and a good ground, but then nothing. Very odd. Other than creating another ground strap, what would be the solution? I seem to remember seeing an article about the horn wiring, and somethign about one wire versus two.

 

[m880 unimog]

one of those foot operated switches used for high / low beam ? or just a button on the dash? it,s suprising how hard it is to get parts for trucks that are ony 34 years old!