Urambo Tauro

1995 Mustang GT, 172,000 miles

I’m finally getting around to an issue that’s been plaguing me for a few months now. The horn failed shortly (immediately, perhaps?) after replacing my cruise control switches. Cruise control has been working fine ever since, but I can’t be sure of exactly when the horn failed, as I don’t use the it every day.

I have confirmed that the horn itself functions by sounding the alarm with the key fob. But the horn pad won't activate the horn.

I was starting to consider a clockspring issue, but I have reason to believe that the replacement of my CC switches is the cause of this. When I received the new switch assembly a few months ago, I immediately put it in, noticing (but ignoring at the time) that the wiring was slightly different:

The new CC switch assembly (labelled F5ZC-9D780-AA, which came in a Motorcraft box marked “F5ZZ-9C888-AB”) has one 3-wire connector, and two spade clips on the purple wire, which connect to the base of the spring-loaded horn bars. The original CC switch assembly (labelled F4ZC-9D780-AA) is identical EXCEPT for the addition of two spade clips on the black wire, which (if memory serves me right; it’s been a few months) I think go to the top part of the horn bars.

According to my Chilton book (which I intend to replace soon with a factory manual), the cruise control wiring is indeed different on 1996 and later models. HOWEVER, the diagram for models up to 1995 does not even show the horn as part of the CC circuit at all.

I have the wrong switches, don’t I?
Can I splice into the black wire and connect it to the upper part of the those spring-loaded horn bars?
Am I remembering correctly that this is the proper way that the old switches were installed?
Or is there more than meets the eye here, and the wiring is even more different than I’m guessing?

Urambo Tauro

I tested the clockspring today, and all circuits are fine.

Fortunately my new manual arrived today as well, so I now have an accurate wiring diagram. The proper wiring for the steering wheel's horn and cruise control switches matches what the Chilton book claims is for 1996 & later models, despite my car being a 1995 model.

The reason I bought new cruise control switches in the first place was that the “ON” button no longer clicked, and I could only turn on cruise control if I firmly massaged the button. When I removed the assembly to install the new ones, I noticed that two of the old assembly's wires were frayed, almost completely worn through.

Fortunately, for some strange reason I had not yet thrown the old CC switches in the garbage. After looking at them, I found that repairing them wouldn't take much. Underneath the "ON" button, there was a rubber bushing out of place, which goes between the plastic rocker button and the actual switch module. I repositioned the rubber, holding it in place with a dab of silicone, and with everything assembled, the button clicks normally now. I also repaired the broken wiring.

So I decided to put the old, repaired CC switches back in, and as I did so, I found that the spade connectors are of different sizes. This forces me to attach the purple ones to the bottom of the horn switch, and the black ones to the top of the switch. No need to worry about my hazy memory after all.

I put it all back together, and it's fixed!

Urambo Tauro

Now, what about those brand-new switches I bought?

Unfortunately, after several months on the car, they are not returnable. If anyone reading this is interested in these barely-used switches, send me a PM. Until then, they'll sit on my shelf just in case my old ones fail beyond my ability to repair.

They are said to be for 1994-2004 models, but as you can see, they won't work on a 1995 like mine without a little modification. Your car may be plug-and-play, but if it's like mine, here's what you need to do:

To make these work in an application like mine, all you have to do is splice in some extra wire and two female spade connectors into the BLACK wire. That's it. This will allow the horn circuit to function properly, without sacrificing cruise control functionality.

Hope this helps anyone else who encounters the same problem!