I have a 99 f150 5.4l and My horn is stuck I pulled the fuse so I don't have to listen to it and whenever I try to put the fuse back in my horn is still stuck, cruise control also doesn't work. I tried replacing the clock spring and that didn't solve anything I checked the fuses and swapped the relays and its still stuck. I also pulled the plug on my cruise control servo and made sure the contacts were clean and dry. everything I try doesn't seem to work does anyone else have any other suggestions.
,thanks

 

Does the cruise work if you unplug the horns? Are the horns still stuck if you unplug the cruise module? It sounds like you know the two problems are likely related as for some reason the truck is designed so the horn doesn't work if the cruise is unplugged.

 

Hello guys,

today I replaced the cruise control buttons on my 99 F-150 Lightning, because the buttons became stiff so that it was almost impossible to get the cruise control to work. I did take off the steering wheel as I also changed the wiring with the buttons. When I put the battery back on, the horn started blowing constantly, so I took out the fuse and started for a test drive. I realized, that the cruise control is also not working. I took the steering wheel apart again and checked all connections I touched previously and everything looks fine, but nothing changed.

Could this be the clock spring? I did take off the steering wheel by hand, not using a special puller, so I did use some force hitting the wheel from the back to get it off. Could this cause the clock spring to break in such way that the horn my be grounded to blare constantly and the cruise to stop working?

That really is the only idea I have but not sure if this could even be it. Maybe somebody on here knows if this could be reason.

By the way, the airbag light is off, so this part of the clock spring seems ok.

Thanks in advance for any suggestions from your side.

cju

 

Most likely, one of the horn switches is closed which will cause both symptoms (horn blows, no cruise).

 

Thanks for the idea.
I did check the mechanical switching of the horn on the steering wheel, there seems nothing to be connected (actuation via the horn pad). Is there a certain switch you have in mind, that would cause this?
Do I understand correctly that in case the horn blows, the cruise control is automatically deactivated?

By the way, after installing the new cruise control buttons with the wiring, I did make the mistake that I squeezed the wiring that goes from the ON/OFF buttons to the other buttons (with the screw that holds the airbag on the left side). That damaged two wires and kind of shut the mechanical actuation part of the horn. So I first thought that was the problem and switched the wires back to the old ones (but kept the new buttons). Could that action be a problem? Could that possible short circuit in the cruise control wiring cause the buttons to be damaged in a way that I have the described symptoms? I mean the short circuit should be gone now.

Could I assume that the clock spring is not the problem, if the horn blows?

Any further idea would be much appreciated.

 

I found the problem now!
The problem was that the connector to the ON/OFF buttons on the steering wheel was plugged in the wrong way. I am really surprised that it is even possible to connect an electrical connector either way in a MJ 99 vehicle.
Of course it is my own fault, because the buttons come as one part with the wires installed and I just had to replace them with the old ones since I was stupid enough to squeeze my new wires with the screw, as I wrote yesterday.

Maybe that information helps the on or other guy if replacing the cruise control buttons. They actually come with the wiring connected to the buttons, but I am sure many people will leave the old wiring in the steering wheel and just replace the buttons to avoid having to deal with the airbag connection and uninstalling the steering wheel which can be a pain if you do not have a pulling tool for it.

I am happy with my truck again.

cju

 

Glad to hear you found the problem. How did this make the horn stop blowing?

I feel like a moron when it comes to electrical problems and electricity in general but I'm trying to learn, which is why I was looking at the thread. If this had happened to me I'd have gone full crisis mode. lmao!

 

Well, I did plug in the connector on the buttons the right way and everything was all right. I also love to hate electrical stuff, I am a mechanical guy, but I was lucky, the dad of my son's friend came by and saw me on the truck and asked if he could help. It turned out he is a professional electrician so I handed him my multimeter and we went through the connections inside the steering wheel and found that problem. I would have never found that on my own, I already thought I had to bring the thing to a workshop. But today I could relax and use the cruise control on my way to work. I love my truck again!

 

Now I really do wonder if they are connected somehow, like if you blow the horn the CC disengages as a safety feature. Gonna have to experiment now.

 

No.


When the horn switch circuit in the steering wheel is closed, it causes the speed control circuit switching circuit, which uses the same wires in the clock switch, to be inhibited. Therefore, you cannot activate the speed control while the horn switch is activated (horn blowing).

 

The Cruise Module receives "Resisted" voltage that determines which switch is being activated. The Supply Voltage is from the Horn Relay "Control" circuit. When the Horn activation Switch is operated, the this Voltage is directed to ground completing the current through the Horn Relay Activation Coil which in turn Closes a Switch within the Relay to send Power to the Horn(s).
The Current that is flowing on the Voltage Supply Circuit when the Cruise Switches are activated is too Low to activate the Horn Relay Control Coil. When the Horn Activation is occurring, the Supply Voltage to the Cruise Module is not present.
A lot of FoMoCo vehicles have this similar configuration. Many of the F Series Trucks have the Horn Switches incorporated within the Driver's Air bag Assembly. There generally are 2 sets of Switches for these Air Bags and the Horn Circuits can be disconnected without disabling the Air Bag. Many of my Clients have Opted to install a Remote Horn Switch to the left of the Steering Column on the Dash instead of purchasing an $800.00 Air Bag. This allows Cruise, Horn, and Air Bag operations without the Higher Costs but slightly inconvenient to operate the Horn.
This isn't so much of a inconvenience to me as I drive a 1984 C-Vic Station Wagon with the OEM Horn Switch operated by pushing in on the Turn Signal Handle.

 

2 year old necropost?

 

Not even close to being a nominee for this week's Lazarus Award....

 

What if horn relay was removed by previous owner. Horn or Cruise did not work. I replace the relay now the horn works but it sounds like a little kid horn. I am not good with a multimeter so I don't know if it's getting the correct amount of power. If so could just make the cruise control not work?

 

Very likely the horn has to be replaced because it's damaged from being powered long time intervals, to many times.