Make it go "HOOT" tracing an itermittent horn

I firmly believe that no matter how good an old Jeep looks to viewers, the owner always knows that there is just “one more” thing that needs to be improved on. Ham’s ’48 is certainly in that category – maybe more than “one more” thing on the list, but still – there is a list.

One of the mysteries that had lurked in the beast since the first days it awoke from its 35-year hibernation was; “Why won’t the horn blow today?” It had a new wiring harness, the horn had been rebuilt but one day it would blow, the next day it wouldn’t and some days it wouldn’t stop blowing until it was good and ready.

SO, early this month I decided that it was time to get to the bottom of the mystery. I grabbed a handful of clip leads and started testing things. The connection from the battery to the horn was good – it always had power to the hot side, one wire was eliminated as being the problem. If I grounded the other horn terminal with a clip lead, it hooted every time, so it wasn’t the horn. The wire from that terminal of the horn wanders through the harness and breaks out just below the steering column. There is a Bakelite plastic connector there, so I checked it out. The connector and the wire back up through the harness to the horn was good – another wire segment checked OK.

All that was left was the wire that runs up the steering column to the terminal under the horn button. I connected my meter to the wire coming out of the bottom of the steering column and checked for continuity to the horn button contact. It was good too – but then it wasn’t.

If I wiggled the contact that was crimped to the wire at the horn button end, it was intermittent! Finally – something that made sense. I put on my set of magnifiers and looked very closely at the contact that has been crimped to the horn wire. The horn wire has a color-coded outer cover and a rubber inner layer of insulation. The contact has two sets of crimp ears; one to be crimped to the two layers of insulation to give mechanical support and one set to be crimped to the copper inner conductor for the electrical connection. When the harness was made, the wire had been improperly stripped. The ears that were supposed to crimp the insulation did indeed catch both layers, but the inner rubber insulation had been improperly cut. It stuck way out beyond the outer layer of insulation. The second set of crimp ears were crimped to the rubber inner insulation instead of the copper center conductor. The only contact with the conductor was when the wire happened to flop around in the barrel of the contact. (The attached picture may make more sense...)

I talked to Mike at KWAS and he sent me a horn button kit for the little Jeeps. It was close, but the center contact for the little Jeeps is a flat contact; the truck needs a more rounded contact, so that didn’t work out.

SO, I put my magnifiers on again and started trying to peel the old contact off the wire. I broke some of the crimp fingers, but there were enough left to squeeze the contact back on and I was able to make a pretty fair solder joint to get a good electrical connection. The horn hoots reliably now. I still need the conical spring to make it a little closer to original, but it works better now than it has worked since 1962 when the whole horn guts came out of the wheel and my Dad just rubbed the wire on the nut to blow it.

Now, on the next project on the punch list – that leaky differential vent!