faulty horn?

dark_knight

Member +
it's only recently that i noticed that when i rev my engine slightly (i'd presume around 2k revs since i'm not at the drivers' seat at the time) my horn seems to sound like it's trying to bleep - almost kinda like you are slightly touching the horn button but not fully pressing it in. i noticed this when i was bleeding my cooling system of air after a coolant flush as i was revving the engine from the intake mani. you would almost not notice it over the engine noise when you are standing a few inches from the car but interestingly enough, it does happen.

my question is; has anyone else experienced this and could it mean a wiring fault..? i highly doubt it's the horn itself since this is my 3rd horn to test. and anyway, the line should only be energized when the honk button is pressed on the steering wheel.. this is not the best pic but it shows a little peek of the horn and wiring going to it.
 

weeJohn

Lifer
The horn is wired with the positive through the horn and it is switched to earth at the steering wheel to complete the circuit. So if you have a short to earth from the wire from the horn to the steering wheel you will have current flow and the horn will sound.
 

dark_knight

Member +
@weeJohn: makes good sense - however - why only when revving..? i am certain there is not short anywhere along that line as i did a voltage drop test on the horn line when i was swapping out my steering wheel and had decided to check the whole circuit. it passed. i was just wondering whether it's possible to have a voltage leak, even if in minuscule quantities across the circuit when revving as i'd assume the alternator kicks in some extra juice thru the line before the in-built voltage stabilizer cuts it out.. this is at times visible if you have a sensitive multimeter or for instance a t/timer like apexi that has the in-line/inbuilt voltage reader.
 
Top