Horn

After I got home, I put some oil in the horn compressor and tested it. Worked fine, so I thought that it was a simple and quick fix. I didn't even have to take the compressor apart and clean it.

The next time I drove the car, the horn didn't work. Aargh! At least this time I was just trying to get someone's attention as opposed to needing it as a warning to another motorist.

So I got out the volt meter and found that there wasn't any power getting to the horn. I got out the owner's manual and spent a few minutes blowing up the wiring diagram big enough that I can follow it without using a microscope. I also copied the legend and relay information. Now I was ready to find the problem. The fuse was fine. Jumping power directly to the horn made it work, so I could forget needing to do anything up front. Closed the hood (or is it the trunk since the engine is in back?). I swapped relays with an identical one known to work and that didn't solve the problem. Then I checked to see if the horn button was grounding the lead at the relay. No ground, so the problem now moved to the driver's side of the car.

I removed the steering wheel and then found out that the horn button (unlike the 330), just pulls off. Re-installed the steering wheel. Grounding that wire didn't blow the horn, so I played with the wiring bundle below the steering wheel. Grounding the wire there did blow the horn, so the problem had to be in the slip ring and brush that allows the wire connection to work as the wheel is turned. In fact, turning the wheel about 1/2 turn to the left or 1/3 turn to the right enables the horn to work. So that's why it probably worked when I first oiled the compressor. I imagine that the wheel wasn't straight and the slip ring and brush were in contact. However, having to turn the wheel in order to blow the horn isn't too desirable in most circumstances, so I continued working on the problem.

To remove the steering wheel hub requires a special tool that has four tabs that fit into slots in the nut.

As I didn't have such a tool, I measured the nut diameter and bought a 1 3/16" socket. Then I located where the tabs needed to be on the socket and removed the material in between them.

Once the tool was made, I was able to remove the nut and hub.

As usual, things don't go as smoothly as one would want. I finally figured out that there was a spring loaded piece of brass that is supposed to touch the round brass ring in the picture above. The problem was that it was so worn that it was bottoming on the plastic part of the ring.

You can see the bend in the brass piece. That's where it was touching the plastic ring. After looking at the mechanics of the piece, I decided to not make and replace the whole thing. So I made a piece to solder on the end to add the length that has been worn away. I didn't have any appropriate thickness of brass, but had some copper. I cut, bent and soldered on an extension. I made it L-shaped so there would be better contact with the brass ring.

Now in the process of taking this all apart, one had to remove the metal piece with the C-clips that hold the various stalks in place. I should have put the C-clips back, but I didn't. Of course, the wiper stalk came apart with springs, ball bearing and the contact flying in all directions. I was able to find them. Then a little tiny piece came out from under the headlight/turn signal stalks side. So I had to take that side apart too. The design is almost identical to the stalk system on my 330 GT, so I had already figured out the best way to put everything back together. Click here for more detail. The special tool that I used to put the ball bearings back in place on the 330 didn't work on the 308 because the center part stuck up too far. So I used a piece of aluminum that I put a detent into using a center punch. This kept the ball bearing on top of the spring while you pushed it into the recess and then pushed the stalk down on the pivot.

I finally got everything back together and the ohm meter confirmed that I was getting good contact completely when the ring was turned. So I buttoned up everything. I had removed the horn fuse so I wouldn't blow it by accidentally grounding the horn lead. This just kept the horn from blowing, but the relay would still click. As I was tightening the special nut, I could hear the relay clicking even though I wasn't touching the horn wire. That was a bad sound. I reconnected the fuse and found that the horn would blow simply from turning the steering wheel. I ended up removing the wheel and hub again.

Once apart, I found that I had forgotten to align the plastic ring with the holes in the back of the hub. Once I put that right, the horn wire no longer touched the hub as you turned the wheel. So finally I was done and the horn works when it should and not when it shouldn't.