Hi all. I had the issue where the horn would constantly blare. Troubleshooting led me to determine my horn switch was always closed. I designed and printed a 1mm spacer to add some more separation between the two contact pads and now it functions properly again! To give credit where it's due, this video by GEARBOX GARAGE: Jeep TJ horn diagnostic and repair, was my starting point.
To start, I recommend reading the manual on the horn switch description and operation (in the '98 manual it's 8G "Horn Systems"), get to the last sentence that says "If the horn switch should fail, or if the airbag is deployed, the airbag module trim cover and horn switch must be replaced as a unit," and laugh maniacally because we're better than them and I'm not paying $100+ for a used airbag unit with a horn switch that may or may not work. All jokes aside, it's good to know how it works and reading all of 8G "Horn Systems" helped me troubleshoot my problem.
I'm going to skip past removing the Driver's Side Airbag Module and Driver Side Airbag Trim Cover and Horn Switch. Those instructions are in the manual in section 8M "Passive Restraint Systems" and have all the nice warnings and graphics to gain access to the horn switch. I will parrot the manual though and say to please be safe and disconnect the battery several minutes before starting.
There she is in all her constantly closed, blaring the horn and making my wife and neighbors angry, glory. In order to remove the plastic cover, unfortunately you'll have to cut through all 10 rubber tabs because they are holding cover in place.
I believe I read on another thread the rubber tabs were melted on to secure the plastic cover. It's not enough to cut off the excess rubber skirts around the tabs, you have to cut through all of the tab to reveal a bridge encapulated by the melted rubber. Once the tabs are all cut, the cover can be removed and the horn switch can be pulled out. I guess if you want to keep the rubber tabs, you can try to sever the bridges from the rest of the cover.
In the video, the presenter said all he had to do was cut some of the blue perimeter to gain access to the switch and shove a stick in there to separate or peel off the two pads from each other. I tried that and when I connected my horn back up to the steering wheel, the switch was still constantly closed.
Since I had already cut some of the perimeter, it was easy for me to disbond the rest of the perimeter and fully separate the two pads. If you want to skip the cutting and fully commit to regluing everything together, try starting the separation at the tab that is inbetween the positive and ground wires. I think you should be able to more easily peel the two pads apart there. With the two pads apart, you can appreciate how the switch operates and how it's supposed to create separation between the pads. On the positive side pad, there are a bunch of tiny bumps that act as a very tiny spacer. When you press on the airbag trim cover, the ground pad is pressed into the positive pad and completes the circuit for the horn relay to switch closed and provide battery power to the horns. For my issue, I think the root cause is either some of those bumps are worn down enough to no longer provide separation between the two pads. You can also see in the photo that my ground pad is wavy so it's possible the deformation is enough to overcome the bumps and bridge the gap without need for human intervention (aka whenever I'm angry at the guy in front of me sitting at the stop light when it turned green and he's on his phone so he hasn't noticed and it's now been 7.9 seconds why haven't you moved yet I'm trying to get home to snuggle my dog).
Solution time! Honestly it's pretty straightforward from here on out. I designed and 3d printed a 1mm thick spacer to go around the perimeter. I tested it to make sure it was thick enough to provide enough separation but thin enough so that you don't have to ram your palm into the steering wheel to bridge the gap. 1mm worked for me but YMMV. I've provided the .STL as an attachment. For those who use Onshape as their CAD program of choice, you can search for it in Public using "98 Jeep TJ Horn Switch Spacer" and make a copy to edit it as you see fit. For 3d printing, I used PLA as I like to prototype with that filament and then I usually switch to PETG for final installation. I didn't do that this time because I was lazy so my final PLA prototype is what is installed. Even though I'm in FL, I'm not too worried about it warping/deforming due to the heat. It is only 1mm thick so it's already going to deform from pressing the horn and I've never had PLA prints + heat manipulate thickness of a piece. If after this summer my horn decides to sing to the gods, I'll print it again with PETG.
From here I was too excited to finally make noise again with my jeep whenever I COMMANDED AND NOT SOME THIN PIECE OF COPPER so there are no more photos. I glued the positive and ground pads to either side of the spacer. I used super glue because that's all I have. Ideally, you should use some adhesive that is non-conductive and can glue plastic to metal. Rubber cement is what I'd use if I had any and like in the last paragraph, I've already established I'm lazy. Put the horn switch back in the slot on the trim cover. I placed it how I originally found it which is the ground pad is adjacent to the cover and the positive pad is facing up/us/the airbag. You can also refer to the first photo for orientation. Glue the plastic cover back on and the rest of reinstallation should be followed using the manual (section 8M "Passive Restraint Systems").
Thank you for reading. You can now go and tell the world you're the best driver and the other guy did something wrong.
To start, I recommend reading the manual on the horn switch description and operation (in the '98 manual it's 8G "Horn Systems"), get to the last sentence that says "If the horn switch should fail, or if the airbag is deployed, the airbag module trim cover and horn switch must be replaced as a unit," and laugh maniacally because we're better than them and I'm not paying $100+ for a used airbag unit with a horn switch that may or may not work. All jokes aside, it's good to know how it works and reading all of 8G "Horn Systems" helped me troubleshoot my problem.
I'm going to skip past removing the Driver's Side Airbag Module and Driver Side Airbag Trim Cover and Horn Switch. Those instructions are in the manual in section 8M "Passive Restraint Systems" and have all the nice warnings and graphics to gain access to the horn switch. I will parrot the manual though and say to please be safe and disconnect the battery several minutes before starting.
There she is in all her constantly closed, blaring the horn and making my wife and neighbors angry, glory. In order to remove the plastic cover, unfortunately you'll have to cut through all 10 rubber tabs because they are holding cover in place.
I believe I read on another thread the rubber tabs were melted on to secure the plastic cover. It's not enough to cut off the excess rubber skirts around the tabs, you have to cut through all of the tab to reveal a bridge encapulated by the melted rubber. Once the tabs are all cut, the cover can be removed and the horn switch can be pulled out. I guess if you want to keep the rubber tabs, you can try to sever the bridges from the rest of the cover.
In the video, the presenter said all he had to do was cut some of the blue perimeter to gain access to the switch and shove a stick in there to separate or peel off the two pads from each other. I tried that and when I connected my horn back up to the steering wheel, the switch was still constantly closed.
Since I had already cut some of the perimeter, it was easy for me to disbond the rest of the perimeter and fully separate the two pads. If you want to skip the cutting and fully commit to regluing everything together, try starting the separation at the tab that is inbetween the positive and ground wires. I think you should be able to more easily peel the two pads apart there. With the two pads apart, you can appreciate how the switch operates and how it's supposed to create separation between the pads. On the positive side pad, there are a bunch of tiny bumps that act as a very tiny spacer. When you press on the airbag trim cover, the ground pad is pressed into the positive pad and completes the circuit for the horn relay to switch closed and provide battery power to the horns. For my issue, I think the root cause is either some of those bumps are worn down enough to no longer provide separation between the two pads. You can also see in the photo that my ground pad is wavy so it's possible the deformation is enough to overcome the bumps and bridge the gap without need for human intervention (aka whenever I'm angry at the guy in front of me sitting at the stop light when it turned green and he's on his phone so he hasn't noticed and it's now been 7.9 seconds why haven't you moved yet I'm trying to get home to snuggle my dog).
Solution time! Honestly it's pretty straightforward from here on out. I designed and 3d printed a 1mm thick spacer to go around the perimeter. I tested it to make sure it was thick enough to provide enough separation but thin enough so that you don't have to ram your palm into the steering wheel to bridge the gap. 1mm worked for me but YMMV. I've provided the .STL as an attachment. For those who use Onshape as their CAD program of choice, you can search for it in Public using "98 Jeep TJ Horn Switch Spacer" and make a copy to edit it as you see fit. For 3d printing, I used PLA as I like to prototype with that filament and then I usually switch to PETG for final installation. I didn't do that this time because I was lazy so my final PLA prototype is what is installed. Even though I'm in FL, I'm not too worried about it warping/deforming due to the heat. It is only 1mm thick so it's already going to deform from pressing the horn and I've never had PLA prints + heat manipulate thickness of a piece. If after this summer my horn decides to sing to the gods, I'll print it again with PETG.
From here I was too excited to finally make noise again with my jeep whenever I COMMANDED AND NOT SOME THIN PIECE OF COPPER so there are no more photos. I glued the positive and ground pads to either side of the spacer. I used super glue because that's all I have. Ideally, you should use some adhesive that is non-conductive and can glue plastic to metal. Rubber cement is what I'd use if I had any and like in the last paragraph, I've already established I'm lazy. Put the horn switch back in the slot on the trim cover. I placed it how I originally found it which is the ground pad is adjacent to the cover and the positive pad is facing up/us/the airbag. You can also refer to the first photo for orientation. Glue the plastic cover back on and the rest of reinstallation should be followed using the manual (section 8M "Passive Restraint Systems").
Thank you for reading. You can now go and tell the world you're the best driver and the other guy did something wrong.
