Replaced battery, horn won't stop blowing

mkluk

Member
Joined
Jun 10, 2007
Location
Bethlehem, PA
TDI
2000 Jetta GL
Hey folks,

This problem is different from the "alarm horn" problem that I've read about. It is just one long solid honk. Not just one small little honk (which is supposed to happen when you reconnect) but a long assed BLOW HONNNNNNK which never stops. Scared the hell out of me b/c it never happened before and I got spark when there was connection... thought I electrocuted myself! Would have been really funny for anybody watching.

This is weird, and I've done some research with no luck finding an answer. I replaced my battery today, disconnected negative then positive, put new battery in, connected positive then negative. Battery was from NAPA.

I have a 2000 Jetta TDI. It is parked on a slope if that matters.

Since I'm in a neighborhood with no garage, I disconnected immediately. Is there any way to disable the horn while connecting the battery, then starting the car, then enabling the horn again? Or, is there a way to stop the horn immediately after connecting? I thought maybe starting the car would stop it, which is suggested for the alarm going off when reconnecting the battery. Haven't tried that yet though because it is officially night time where I am.

Thanks...
-J
 

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
Don't know if this applies, but on my A3, when reconnecting the battery, I had to lock the car and then lock the car with the key to turn off the alarm.
 

Corsair

Veteran Member
Joined
Aug 17, 2003
Location
Weedsport, New York
TDI
2002 Jetta GLS TDI 5M
I work in the electrical / electronics trade, but didn't reply to this because frankly I'm stumped. I'm going to assume the car was fine, driveable etc. and for whatever reason the battery failed or was decided to replace, and on installing the new battery, the horn blows constantly....
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I agree with Ol'Rattler- try cycling the lock etc.
Does the car have any aftermarket alarm we're not aware of ?
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My next move would be to consult the Bentley manual, look at the schematic, see what operates the horn. Maybe there's a "horn" fuse that could be pulled, but that's probably not a good long term solution. Reasons are because there might be other equipment you'd like to have use of... on that same circuit. Also, the horn is typically operated by a relay, and that relay itself draws some electrical current just to turn the horn on. Point is- even if you disconnect the horn or pull the horn fuse, the relay might still be triggered on, and that could drain the battery over the course of a day or two or three. Someone will need to trace the wiring diagram and use a Volt meter to figure out what is causing the horn to blow. If it's the car alarm, I'm not sure whether it would allow the engine to run or not.
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You appear to have one of those "interesting" electrical problems, in the same way that a root canal is "interesting". Wish you all the best, and please do report back what is the outcome.
 

neljoshua

Well-known member
Joined
Oct 9, 2008
Location
CO
TDI
2002 VW Golf GLS
Corsair, you might be on to something.

I have seen relay springs in VWs that have broken such that something is always on.

I do not recall right now where the horn relay is, but that is where I would start. It is possible there is something in the relay that is broken (corrosion, broken spring, etc) that is causing the contacts to stay closed.

mkluk, since you say it is parked on a slope, this may actually have something to do with it as well.

Does anyone know if the 2000 Jetta has a tilt sensor on the alarm system? Is it possible this is triggering since it is on a slope?

Since it is a long blast of the horn rather than the alarm, I would think it is a relay problem rather than an alarm problem. I have seen a number of relays (turn signals, horns, starters, etc) go out for different reasons. Usually, they can actually be fixed, if you know a little bit about relays.

Josh
 

Corsair

Veteran Member
Joined
Aug 17, 2003
Location
Weedsport, New York
TDI
2002 Jetta GLS TDI 5M
Again I learn something good from another poster here- I never thought about that...
If it was an alarm activating, the sound would likely be pulsing BLAH- BLAH- BLAH-
But since it's constant, that may point AWAY from the alarm as a cause.
Good thinking!
 

kenmaira

Veteran Member
Joined
Jan 6, 2011
Location
Austin
TDI
Golf Mk4 2001 1.9 ALH
just replaced my glow plug harness (will post pics soon) and now I have the same problem, ideas?
 

kenmaira

Veteran Member
Joined
Jan 6, 2011
Location
Austin
TDI
Golf Mk4 2001 1.9 ALH
OK, for those who are looking, the way to turn it off is to just turn the key over after you re-attach the battery
 
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