Sticking Horn Contact Fix - Don't Need New Airbag - Ford Powerstroke Diesel Forum
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Old 12-11-2009, 02:21 PM
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Sticking Horn Contact Fix - Don't Need New Airbag

I managed to fix my sticking horn contact on my 2000 SuperDuty - air bags are steep$ and if you try a used one, you don't don't know how long the horn contact is going to work anyway. You can't buy the horn contact separate from Ford, but it does have a TRW part# on it.

Even if your horns are bad and don't sound, a sticking horn contact pulls in the horn relay and will make your batteries go dead in about a week. And if the horn relay is bad or you pull it out, then your cruise will not work.

I put in a new horn relay and checked the horn fuse.....and put in new horns, it wasn't until I put in the horns that I even knew the contact was bad....and that the stuck horn contact was the reason my batteries were going dead. I needed the horns anyway - the old ones would not sound with a separate power source.

Main issue for me was the fact that the cruise wouldn't work when the horn button was stuck (before I replaced the horns, so no noise). The stuck horn button caused the horn relay to heat up and go bad and the cruise would not work with a bad horn relay in there. If your horns are bad, which is common, you probably won't know the contactor is stuck, but it will prevent your cruise from working.

The ironic thing about it that a horn that doesn't work causes people (including me) to push the horn button even harder.....which is what causes the horn contactor to fail.....thereby adding yet another issue causing the horn to not work instead of getting the horn to sound......kind of funny when you think about it - now you not only probably need new horns but the horn contactor is screwed up too.

On to the contact fix:

First, don't remove the airbag from the steering wheel until after you:
1. Disconnect both batteries.
2. Wait about 10 minutes.
3. Pump the brakes a few times - this gets rid of any residual voltage.

Also do not ever use any kind of meter on the airbag. Once you get the horn contact away from the airbag then you can meter the horn contact if you want to but don't do it when it is still in the airbag assembly - you could mix up on the wires and think you are metering the horn wire but you are doing the airbag discharge wires by mistake - NOT GOOD since it may go off !

To remove the airbag, remove the plastic screw access caps (2 total) on the back side of the steering wheel and then take out the two 8mm headed bolts. Lean the airbag out some from the steering wheel and you will see there are 2 wiring plugs to disconnect, the red one by the 2 screws is the horn, the other goes to the airbag. Study the plugs and be careful with your disconnect method so you don't break them.

Here is the back side of the airbag. Remove the 2 screws at the top of the pic, pry the bottom side of the clip U tangs on each side apart a little and the clip will come off and you can open the cover to expose the horn contactor which is 2 films of copper laminated to 2 films of plastic which are adhesived together around the edges. There is a pic of the U clip in the last post below.
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Sticking Horn Contact Fix - Don't Need New Airbag-1-back-airbag.jpg  

Last edited by bob00stroke; 03-30-2010 at 07:17 PM.
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Old 12-11-2009, 02:43 PM
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Here is opening the horn cover - you can see the little hooks on each side that also hold the cover on. Note you actually can't completely separate the cover from the airbag, you can only open it up, there are rivets that keep it attached except for the 2 screws.

2nd pic is the horn contactor itself - 2 films of copper laminated to 2 films of plastic which are adhesived together around the edges.

The 3rd pic shows the tines on the back side of the cover - these are what force the copper films to contact when you push the horn. You can also see the indented area where the horn contactor used to be (missed that pic).

The tines are also what eventually stress the copper films enough to make them stick touching making the horn stick on. If you look closely at the 2nd pic, you can see the indentations from the tines. I think my contact problems seemed to be in the center, near the top - there were some little bigger indents there. You can kind of smooth out any indents with your fingers if you find any, but I didn't worry about them too much. As I already mentioned, the ironic thing about it that a horn that doesn't work causes people to push the horn button even harder.....which is what causes the horn contactor to fail.....thereby adding another issue causing the horn to not work - now, after seeing the tines, you see what I am talking about.

Once you get a little further into the contactor, you will see all that keeps the copper films apart and your horn OFF is a whole bunch of super thin, tiny plastic? "buttons" - they work fine until the copper gets stressed.
Attached Thumbnails
Sticking Horn Contact Fix - Don't Need New Airbag-2-opening.jpg   Sticking Horn Contact Fix - Don't Need New Airbag-4-horn-contactor.jpg   Sticking Horn Contact Fix - Don't Need New Airbag-5-tines.jpg  

Last edited by bob00stroke; 03-20-2010 at 10:50 AM.
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Old 12-11-2009, 03:01 PM
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Ok, this pic shows the fix.

1st: Use a razor blade to gently cut & pull the copper/plastic laminates apart from each other - BUT DON'T PULL THEM ALL THE WAY APART AT THE TOP OF THE OVAL, just far enough to do the silicone beads described in step 5 - leave the 2" or 3" (approx) length of adhesive at the top of the oval stuck together. Start at the little "foot" at the bottom and GENTLY peel the laminates apart.

You can now see all that keeps the two copper films apart and your horn OFF is a whole bunch of super thin, tiny plastic? "buttons" - they work fine until the copper gets stressed.

2nd: Be gentle now, but use some black tape to keep the laminates open from each other, again - don't pull them all the way apart, just far enough for step 5. I just taped the laminate shown peeled open in the pic to the "tongue" where the wires come in.

3rd: Mark where the tines touch with a marker (you are actually marking on the inside, opposite of where the tines actually touch). Put the marks on the copper film that has the tiny plastic buttons on it, these are the short marks in the pic. You have to look close, but you will be able to tell where the tines are pushing the laminates together; you can even see where the tines have caused the copper films to touch in this pic, but you have to look really hard at it.

4th: Get a tube of Permatex Silicone and cut the plastic nozzle end as close to the top as possible to get a very small application hole. As you can see, I used black.

5th: Lay very thin beads of silicone between your "tine contact marks". The silicone beads are going to be your extra "separation springs" for your horn contact. Practice a few beads somewhere else - as you can see, I didn't, and I got sloppy at the left end, but my contact problems seemed to be in the center, near the top.

6th: Let the silicone beads dry with the copper laminates spread apart for 24 hours minimum.

7th: After the silicone beads are dry, undo the tape holding the copper laminates apart - you are now ready to glue the laminates back together around the outside edges, similar to where it was originally glued.
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Sticking Horn Contact Fix - Don't Need New Airbag-6-beads.jpg  

Last edited by bob00stroke; 03-30-2010 at 07:11 PM.
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Old 12-11-2009, 03:06 PM
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This pic shows the copper laminates glued back together, glued around the outside edges only, similar to where it was originally glued - I used GOOP Sport & Outdoor contact cement, it seems to stay a little flexible. As you can see, the paperclips hold it back together. I let the glue dry 24 hours.

You have to be a little quick on this part, I only put glue on 1 laminate outside edge but you could put a thin film on each laminate outside edge if you want. If the GOOP partially drys on you, you can peel it back off and start over, but it gets messy.

The 2nd pic shows the horn contact reinstalled after pulling off the extra glue slop, ready for the horn cover to go back over it.

You can see how the little "feet" of the horn contact fit in at the top and bottom of the airbag.
Attached Thumbnails
Sticking Horn Contact Fix - Don't Need New Airbag-7-glued-clipped.jpg   Sticking Horn Contact Fix - Don't Need New Airbag-3-reinstalled.jpg  

Last edited by bob00stroke; 12-12-2009 at 09:58 AM.
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Old 12-11-2009, 03:13 PM
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Here is a pic of the wire clip - recrimp the U ends over the cover's screw area and check that the 2 hooks on each side of the horn cover are in place also, then put the 2 screws back in and snug up pretty good but don't over do it.

Reinstall the airbag on the steering wheel as you reconnect the 2 wiring plugs. Center the airbag on your steering wheel by looking at the gaps at the edge of the horn cover vs. the cruise switches then snug and tighten the two 8mm headed bolts and reinstall the plastic screw access caps.

Does the horn need more pressure to make it work? Yes, but not that much more. As you know, the horn button doesn't normally get a lot of use anyway.

At this point, I admit I don't have a lot of time on this fix, I guess the silicone could degrade over time or the glue could let go, but I didn't see a lot of choices short of buying an air bag. If it fails, I tend to think it will just stop the horn from working rather than making it stick ON. Edit 3-30-10, 10-27-10: Still working fine, but don't really go around honking my horn a lot either.

Main issue for me was the fact that the cruise wouldn't work when the horn button was stuck (before I replaced the horns, so no noise). The stuck horn button caused the horn relay to heat up and go bad and the cruise would not work with a bad horn relay in there.

That's all on the horn contactor (except for pic at bottom).

REPLACING THE HORNS
(Before replacing the horns, after taking them out, first make sure they are bad by checking with a separate power source....I used a battery charger, but you could connect them direct to the truck's battery too.)

1. The horns are up under the front of the passenger side wheel house. Take out the various front and center wheelhouse bolts, screws, and push in clip(s). Pull the front of the wheelhouse down and hold it with a strap or let a helper hold it. The wheel house will bind on the inside edge of the fender and probably bend this edge a little, you can tap it back into place with a hammer handle or plastic hammer when you get the wheel house back in place.

2. Take out the battery, then there is only one bolt holding the whole two-horn assembly - the bolt is about even with the front edge of the battery, but the battery is in the way enough that it is easier just to take it out.

3. The new horns come with a bunch of adapter type stuff you won't need, just reuse your old wire connectors and mounting bracket, but the contacts on the new horns may not be in the exact same place as your originals, but it all ends up pretty close to original, just make sure the wires don't end up in a position where they are going to get rubbed through. Also, note the horns are marked "H" and "L" for high and low tones, keep them in their original locations on the mounting bracket. I think the horns were around $75 for the pair, but the Ford parts guy gave me a deal, I think you are talking around $95 normally but can't remember for sure.

CRUISE CONTROL FIX
If you messing with your horn contactor, chances are you may have Cruise Control issues as well....so here is a link to a thread with my trials vs. the cruise control: Cruise Control
Attached Thumbnails
Sticking Horn Contact Fix - Don't Need New Airbag-8-wire-clip.jpg  

Last edited by bob00stroke; 01-26-2012 at 09:40 AM.
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Old 12-11-2009, 03:52 PM
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Thats some great info.
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Old 12-11-2009, 03:55 PM
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wheres the horn relay i couldnt find it??
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Old 12-11-2009, 04:06 PM
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If I remember right, it's the 2nd relay down on the left in your under dash fuse box.

In your manual, in the fuse section if you go to the very bottom of the chart they list the relay locations.
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Old 04-05-2010, 06:46 PM
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Thanks Bob00stroke. I will be attempting to fix my horn contact problem this weekend for inspection. Your writeup will help a bunch.
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Old 05-16-2010, 05:33 AM
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hope someone is out there, looking for my horn relay on 2004 f350, manual shows the fuse location but not the relay, it was blown, i hear the relay but i want to check power leaving the relay towards horns before go under the fender well. the horns are under the passenger wheel well, correct?
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