Help! Horn killing engine or dropping idle!

[f1rchifi]

This is really weird and is baffling all auto electricians here even in the dealerships. They say they have never experienced this problem. I have a 1996 Galant 4G63 SOHC. (2 units actually with the same problem).

Problem is when I blow the horn, idle drops and often the engine dies. The horns I have used are Bosch Supertone (black), Fiamm and Bosch Fanfare horns, and now installed Stebel Magnum Fanfare horns. All are wired properly with the use of a relay etc. Wiring has been double checked. Battery is new and strong, alternator charges very well. One guy from the speedshop even tried isolating the horn button from the car's electrical system just in case it affects the ECU voltage etc. Still the problem exists.

My headlights use 80/100W H4, and 80W H1, no problem when the lights are on or flashed and I expected the load to be even more than a pair of horns. I feel the load on the alternator, when the horn is activated, is causing the idle to drop or kill the engine. But why should it when the load is much less than the lights or AC.

Getting helpless with this problem! Short of opening the window and shouting instead of using the horns.

Thanks for any help.

 

[moliver]

Have your replaced any of the wiring for the horn?

 

[funniegus]

Dont know if its the same but I think I read a thread somewhere that some evo's would die when a car with loud exhaust would pass by. They said that their mafs were very sensitive for some reason. This might be what youre experiencing when you press youre horn.

 

[TotalEclipse112]

It could be the MAF since they do create a frequency which is hoe the ECU reads the air flow. But what you are experincing sounds like a massive short to ground. It only happens when the horn is activated, could be a massive amount of voltage being drawn through the short causing the load on the altinator. But since you have chencked the wiring try the horn windings on the behind the steering wheel that could be the culprit

 

[f1rchifi]

Thanks guys! Wiring is okay. Will have MAF checked and see if I can isolate the horn mounting to lessen the vibration and noise within. Maybe it's better to put the horn in the trunk! !

 

[luv2rallye]

I agree it almost sounds like a massive short in the horn circuit. Try disconnecting the horns and pressing the horn button to see effect. If nothing happens (no idle drop or extra load on alt.), try connecting each horn 1 at a time to the battery thru progressively smaller fuses (30A, 20, 15, 10, 5, 3, 1) till fuse blows to see approximately how much current is actually there. You can then do the same with a stock horn to compare.

 

[ChrisFlo]

Do you honk at a lot of people?