Stock Grand Cherokee Tech. All ZJ/WJ/WK Non-modified/stock questions go here! ZJ (93-98), WJ (99-04), WK (05+)
All ZJ/WJ/WK specific tech questions asked here!

horn keeps blowing when parked unattended

Thread Tools
 
Search this Thread
 
Old 02-13-2017, 10:04 PM
  #1  
Newbie
Thread Starter
 
Pe Pop's Avatar
 
Join Date: Feb 2017
Location: Limerick, PA
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 1999
Model: Grand Cherokee
Engine: 4.6
Default horn keeps blowing when parked unattended

Have a 1999 Grand Cherokee Limited 4.6 V-8 engine 200,000 miles.

My current problem is horn keeps blowing when parked unattended at will for unknown reason.

This past Saturday early morning had to disconnect battery terminals, when horn blasted me out of bed. After removing battery cable, decided to clean terminals with wire brush when reinstalled, horn did not blow, great! Problem fixed itself wahoo!

Next day used wife's car as we needed to run errands, when returning home late Sunday night, my neighbor met me at my door stating my jeep's horn was blowing for ten minutes, he was kind enough to disconnect my battery saving my jeep from being destroyed by irate neighbors holding pitchforks & brooms.... scary!

Anyone ever had this happen to them? What can I do for a quick repair?

Appreciate it,
Pe Pop

Last edited by Pe Pop; 02-13-2017 at 10:12 PM.
Old 02-13-2017, 10:43 PM
  #2  
Member
 
Hatsuwr's Avatar
 
Join Date: Aug 2016
Location: Maryland
Posts: 228
Received 2 Likes on 2 Posts
Year: 1996
Model: Grand Cherokee
Engine: 4.0 I6
Default

Don't have a WJ, but I think this is your horn circuit diagram.

Is it a constant/sporadic tone, or a regular on and off honking?

If the latter, I'd look into the alarm system.

If the former,
Just saw your other post. Since it is a constant tone, I'd troubleshoot the components on the diagram below. Relays are easy to test, so I'd start there. If not that, maybe check the horn switch and clockspring.

That's not to ruse out the alarm system completely, but it seems less likely.


Last edited by Hatsuwr; 02-13-2017 at 10:51 PM.
Old 02-14-2017, 05:53 AM
  #3  
Old fart with a wrench
 
dave1123's Avatar
 
Join Date: Nov 2010
Location: Manlius, east of Syracuse, NY
Posts: 14,398
Received 723 Likes on 628 Posts
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
Default

Has it been extremely cold lately? The plastic shrinks around the horn switch under the airbag and sets it off. You could just pull the fuse for now. OR the relay so you'll still have your power outlet.

Last edited by dave1123; 02-14-2017 at 05:55 AM.
Old 02-14-2017, 08:27 AM
  #4  
Newbie
Thread Starter
 
Pe Pop's Avatar
 
Join Date: Feb 2017
Location: Limerick, PA
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 1999
Model: Grand Cherokee
Engine: 4.6
Default

Originally Posted by Hatsuwr
Don't have a WJ, but I think this is your horn circuit diagram.

Is it a constant/sporadic tone, or a regular on and off honking?

If the latter, I'd look into the alarm system.

If the former,
Just saw your other post. Since it is a constant tone, I'd troubleshoot the components on the diagram below. Relays are easy to test, so I'd start there. If not that, maybe check the horn switch and clockspring.

That's not to ruse out the alarm system completely, but it seems less likely.

Thanks for the useful insight & wire diagram!

Pe Pop
Old 02-14-2017, 08:29 AM
  #5  
Newbie
Thread Starter
 
Pe Pop's Avatar
 
Join Date: Feb 2017
Location: Limerick, PA
Posts: 7
Likes: 0
Received 0 Likes on 0 Posts
Year: 1999
Model: Grand Cherokee
Engine: 4.6
Default

Originally Posted by dave1123
Has it been extremely cold lately? The plastic shrinks around the horn switch under the airbag and sets it off. You could just pull the fuse for now. OR the relay so you'll still have your power outlet.
Another sound solution, thanks!

Pe Pop
Old 02-14-2017, 10:16 AM
  #6  
Old fart with a wrench
 
dave1123's Avatar
 
Join Date: Nov 2010
Location: Manlius, east of Syracuse, NY
Posts: 14,398
Received 723 Likes on 628 Posts
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
Default

I see what you did there!
Old 02-14-2017, 08:36 PM
  #7  
Member
 
Cleman Simpson's Avatar
 
Join Date: Sep 2016
Posts: 137
Likes: 0
Received 0 Likes on 0 Posts
Model: Cherokee
Default

Originally Posted by dave1123
Has it been extremely cold lately? The plastic shrinks around the horn switch under the airbag and sets it off. You could just pull the fuse for now. OR the relay so you'll still have your power outlet.
LOL, You don't need to be teaching high school auto mechanics, you need to be teaching at MIT or oxford.
Old 02-14-2017, 09:41 PM
  #8  
Old fart with a wrench
 
dave1123's Avatar
 
Join Date: Nov 2010
Location: Manlius, east of Syracuse, NY
Posts: 14,398
Received 723 Likes on 628 Posts
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
Default

Actually, this goes back to a problem I encountered with my boss's new Oldsmobile in the 70s. It had a squeeze-ring for the horn. The horn went off in the hot sun because the plastic swelled. I told him to just leave the windows cracked open an inch or so, and that cured the problem.

I worked in plastic molding most of my adult life. You can change the finished product's size by controlling the molding process; ie cooling time and injection pressure.

Last edited by dave1123; 02-14-2017 at 09:45 PM.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 



All times are GMT -5. The time now is 05:27 PM.