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Horn Contact Update on IdidIt GM style column

3990 Views 3 Replies 3 Participants Last post by  gnsh
A known weak spot in the horn circuit of the IdidIt GM style column is the small spring that pushes against the horn contact on the back side of the horn ring cam. This configuration consists of a spring pushing on a brass plunger, with the weakness being that if the current in the horn circuit heats up the spring, it loses its “springiness” and you are without a horn. In order to fix this part you have to pull off the wheel and the horn ring cam to replace the "burned spring" = PIA! The the spring wire is very small at only .012” in diameter so it is easy to see why this is the weakest link…almost like an inline fuse waiting to blow with the slightest bit of current.

When switching to the IdidIt GM style column on a 1965 Mustang part of the process is to reorient the circuit so that negative grounding is connected through the horn button (GM Style) via a relay instead of having the circuit complete by the connection of two positive leads (Ford Style).

In my case I have the dual horn setup on the car, so the relay is even more necessary. I previously updated the wiring to use a Bosch 0332019155 relay (which is similar to the 0332209150 except that it has an internal diode to handle flyback) and I am only running the negative current through the column.


The interesting thing is that if you look around at other options for horn contacts they have a wire inside to carry the current and protect the spring from the overheat situation. Here is an example of a Scott Drake Horn Button Contacts C2OZ-13A821-A that I was considering, however the plunger is missing the small lip and I was not sure it would work correctly.


This week I had my column apart for painting and other minor improvements and thought that I would take a shot at solving this weak spot in the design by simply doing what others have done. The bonus here being that if I ever have another current spike hopefully a real fuse will blow rather than a burned spring.

Here are the steps:

  • Small 3mm copper or brass eyelet/grommet
    • The plunger is 0.234" so anything smaller than this will work.
  • Small piece of desoldering braid
    • Braid works better than normal copper wire due to it’s flexibility.
  • IdidIt Horn Kits 2620000010 (2 Sets)
    • Contains two sets of springs/plungers…possibly for the next time it blows?

  • Thread the spring and eyelet onto the desolder braid.
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  • Cut off a few small pieces of solder placing them into the brass plunger, heat them up with a torch, and attach the desolder braid.
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  • Cut off the braid as the full spring extension length and add some additional solder to the end to fill the grommet.
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  • File the back flat.
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  • If you want, add corroboration gel to keep the connections from oxidizing.
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  • Put the plunger back in. This part can be tough as it is tough to line everything up while also pushing the plunger in. I tapped mine in with a hammer after careful alignment and persuasion.

Next up I am going to switch out the IdidIt factory GM wire connector (ugly) for the Ford Mustang style before reassembly. Part number is 9201076250.
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If you are burning up horn contacts then you have much bigger issues with traffic where you are causing you to use your horn that much. Course I used mine a bunch today to and from the swapmeet as I always get stuck behind the cars going 45mph on a two lane road that is 70mph and virtually no passing zones.

The preferred method of wiring is to run positive to the horn button. Ford had a habit of liking to have every wire in the car hot and then using a switched ground. This is bad for diagnosis and oh if a wire shorts your horn blows constantly or your dome lights are on all the time. You always minimize the amount of wire in a car that is hot.

Those connectors that you have pictured are standard bulky molex connectors. They get the job done but are ugly and clunky. I have never seen or heard of that plunger being replaced in any GM or Chrysler vehicle (chrysler used the columns in allot of their vehicles) Also that one looks like the regular cheapie aftermarket part and the aftermarket stuff now is garbage. The aftermarket turn signal switches are also garbage now too.
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I've had my 70 GMC for over 30 years and I've never had to replace the horn contact. But then, I don't lay on the horn for minutes at a time either.
I had a relay short, which is what I think did mine in. Regardless I would still like the fuse to blow rather than burning the contact support spring wire.
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