HORN WON'T SHUT OFF on 2004 AVEO

[rocky49]

Our 2004 base Aveo horn started blasting away on its own while driving last week. Various things have been tried trying to regain control of this noisy beast. 1. First we replaced the horn with another known good one with no difference. 2. Second we changed the plug the horn connects to with no difference. Third I peeled the plastic wrap from around the cables from the horn back as far as the next junction however all insulation seemed intact. Fourth I tried pulling the fuse marked horn rear fog lights on the side of the instrument panel with no difference. Fifth I replace the relay under the interior side kick panel with no difference. Operating the horn from the steering wheel only changes the horn tone. At this point I have only been able to pull the fuse on the under hood fuse box to turn the horn off (aside from disconnecting it, or cutting horn wires.) So the next question where do I check for shorts? Are they under the hood? in the door interior area? Where do I look? or do I peel all of the spiral wrap insulation from the cable back from the horn until I find bare wire? Please provide suggestions I have considered running new wires but I don't really know where to from. Rocky

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[2010AveoLT]

does the horn stop sounding when you pull the Relay? if not, a short is completely bypassing the control side of the horn circuit. (quite Possibly in the UBEC)

[rocky49]

Ok I went out today, put the under the hood fuse back and the horn is blaring. I removed the horn relay under the drivers side kick panel and the horn continues to blare. It is now obvious to me the horn switch in the steering wheel is not the problem. So where is the short? 2010AveoT says it may be in UBEC, What is UBEC and where do I look? Rocky 49

[2010AveoLT]

Ok I went out today, put the under the hood fuse back and the horn is blaring. I removed the horn relay under the drivers side kick panel and the horn continues to blare. It is now obvious to me the horn switch in the steering wheel is not the problem. So where is the short? 2010AveoT says it may be in UBEC, What is UBEC and where do I look? Rocky 49

the UBEC is the Underhood Bussed Electical Center; or in other words, the Underhood Fuse Box.

[rocky49]

After hearing from others the issue must be in the underhood fuse box, I went to pick your part for some training. I found a broken up fuse box and took it apart. The one off a 2005 aveo looks quite a bit different from later models. It became obvious to me that I could not take this box apart on my car in any non destructive manner. So I went back to basics and decided to check for shorts in the wiring harness. Pick your part was again helpful because I could trace the harness back from the horn to junction box. No such luck as any easy spice. I played a bit with their shredded harness and decided to go home and work on mine some morel At home I found that I stopped tracing the horn circuit at the passenger headlight connection. I started peeling crinkle wrap off the harness and found that I had a melted section of wrap, peeled it off and found 3 wires with insulation burned off and bare wires. I peeled the crinkle plastic off for another 6 inches and looked for more bare wires touching. None found. I put the fuse in and the horn blasted. I then separated the wires from each other and the horn stopped. I applied shrink wrap to the three wires separately and then bundled them up with electrical tape. Checked all circuits and everything works properly. For those curious about where the overheated stretch of wires were, it was along the stretch on the lower rad support just past the connection the goes to an engine sensor. This stretch of wire is well supported so the failure was not due to fatigue but overheating. Speaking of heat today in frigid northern Canada it was 40 F degrees in the sun, so it was a good day to work on the Zombie and solve this final problem. Thanks to those who commented and helped with ideas along the way. ROCKY

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