Horn woes

[boxcorsair]

Hi all

So fitted 2 new horns. Thing is that each time I hit the horn push the bottom fuse is blowing. I have the earth across the steering coupling, I have an earth from the steering rack to chassis. I notice a spark from the horn pencil as it touched the inside if the column as I removed and replaced it ensuring it was seated correctly. Also the relay clicks as I connect the battery.

Everything looks to be wired correctly but obviously something is adrift. I have also noticed the main beam light is always on regards of the dash switch... I haven't investigated this yet but they are on the same fuse.... linked to the horn prob?

Any ideas?

[rotoflex]

boxcorsair wrote:

Hi all

So fitted 2 new horns. Thing is that each time I hit the horn push the bottom fuse is blowing. I have the earth across the steering coupling, I have an earth from the steering rack to chassis. I notice a spark from the horn pencil as it touched the inside if the column as I removed and replaced it ensuring it was seated correctly. Also the relay clicks as I connect the battery.

Everything looks to be wired correctly but obviously something is adrift. I have also noticed the main beam light is always on regards of the dash switch... I haven't investigated this yet but they are on the same fuse.... linked to the horn prob?

Any ideas?

The fuse blows because more current goes through it than it is rated for.
Are you using the correct fuse?  The manual says it is 35 amp UK/20 amp US.
Did you have the fuse problem before fitting the new horns?
Or did your previous horns not work at all?
Are these new horns original-type horns, or some high-power modern type?
Are the new horns used items, which may have an internal short?

The wiring diagram show the only things going through the bottom fuse are the horns, horn button, & horn relay.
Has the wiring been changed on the side after the fuse?
Is the wiring correct at the horn relay?
If the horns did not work before, is it possible that the horn relay is bad?

[boxcorsair]

Hi Roto.... thanks for all the queries. The are new lucas horns... the cheap plastic versions. I only had one previously and it's dead (hopefully drill out the rivets and see if I can get it going another time)... however, I am nearly positive it was a 15 or 17 amp fuse in holder 3... will check tomorrow. If that is the prob then all is well and I'll be suitably red faced...


Cheers

[rotoflex]

If when connecting the battery you heard the relay click, it would seem to indicate something else wrong.
The relay should not click until the horn button is pushed.

Two possibilities causing the relay to click when the battery is connected:
1. The horn button is stuck "on"
2.  Something wrong at the relay:  either wired wrong, or the relay has somehow internally shorted.

Even if the horn button is stuck "on", the horns should blow continuously, not blow the fuse (assuming the correct amperage fuse is in place).

I think first that I'd trace every inch of the wiring feeding from the third fuse (it's not much), & confirm absolutely that it is correct.
Then install the correct amperage fuse, & if it blows, try another relay.
Do you have a multimeter?

[boxcorsair]

Yes, I've got a multimeter. The relay definitely clicks on the minute the battery is connected. The horn doesn't sound at all.
However I have found other relay wiring threads on here so will double check that as I wired the relay back as it was prior to strip down as the post markings are not visible on the relay front. Hence all a bit of guesswork really.
I'm not really au fait with the inner workings of the relay but I would presume that incorrect wiring on that side would cause these symtoms!!
I will follow the advice of checking everything wired to the 3rd fuse though. Hopefully solve the full beam lamp issue as well :)
Prob not get back down to the car until Wed, but I will report back

[boxcorsair]

Hi all

Just an update to close this one... if the horns isn't working, slow down and check everything again... relay top and bottom connection were the wrong way round. Must have checked the relay a dozen times :$ All good though and now working (albeit only one horn fitted just now).