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Discussion Starter #1
I've checked & tried different fuse, relay, horns & steering wheel-all work fine until I turn on the ignition, engine running or not makes no difference!

The horn still won't work with the ignition turned off until I remove the key!!!!????

Put the key back in....horn works....turn ignition on....horn doesn't work.....turn ign off....horn doesn't work....remove key....horn works!!!!:mad:

The car is an 04 P3 Spider 3.2 but the electrics are basically the same as the P2's.

I've got an early wiring diagram which is pretty easy to understand...I think.....but I'm thinking perhaps the immobiliser circuit or main ecu might be affecting things but why should it do so with ign off but key still in?:confused:

Any knowledgeable auto electricians out there?

Clive
 

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Thats a strange one mate - I can't say I've ever heard of anything like that before. If you can't find a wiring diagram, you might just want to re-wire from the live, to the horn switch, to the horns, to the earth. Then it bypasses Alfa's strange wiring systems.
 

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Discussion Starter #3
ECU reset?

Thats a strange one mate - I can't say I've ever heard of anything like that before. If you can't find a wiring diagram, you might just want to re-wire from the live, to the horn switch, to the horns, to the earth. Then it bypasses Alfa's strange wiring systems.
How about doing an ECU reset?

Would it show up on a diagnostic?

Clive
 

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Clive
Email sent. The horn does indeed work from the battery.
 

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Discussion Starter #7
New uncoded key

Clive
Email sent. The horn does indeed work from the battery.
Thanks, I've already got the wiring diagram & it's still baffling me!

When testing the relay contacts in the fuse board contacts 85 & 86 are reversed, everything remains correct with or without the ign on but when I replace the relay it only works as before.

If the live feed is constant & the earth comes via the horn push consistantly with ign on or off why do the horns only work when the ign is off?

I can get a key cut tomorrow which I'll not have coded.This would help rule out the key code immobiliser circuit- I will be able to turn the key but not 'arm' the ignition so just physically inserting & turning the key.

I've also got a new fuse board which I can try.

Clive
 

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I had this on my 116 Alfetta GTV6 and it confused the hell out of me, just the same symptoms as you have.

What it was was the " Earthy " connection to Steering Column, this provides the Earth for the Horn Push. When the key was out the Steering Lock provided the Earth path, until you inserted the key and switched on, then the swearing was loud and the Horn very quiet, ie, silent !

On my '6 it turned out to be a broken wire link on the Hardy Spicer joint of the Steering Column, just inside the Engine Bay on the column.

To check if this could be your problem provide a temporary " Earth " to the Steering Column and run through the checks again.

If it does turn out to be a similar problem to mine you'll have to look for the wire link, no idea where or what it is on 916 cars.
 

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Discussion Starter #9 (Edited)
Earth

I had this on my 116 Alfetta GTV6 and it confused the hell out of me, just the same symptoms as you have.

What it was was the " Earthy " connection to Steering Column, this provides the Earth for the Horn Push. When the key was out the Steering Lock provided the Earth path, until you inserted the key and switched on, then the swearing was loud and the Horn very quiet, ie, silent !

On my '6 it turned out to be a broken wire link on the Hardy Spicer joint of the Steering Column, just inside the Engine Bay on the column.

To check if this could be your problem provide a temporary " Earth " to the Steering Column and run through the checks again.

If it does turn out to be a similar problem to mine you'll have to look for the wire link, no idea where or what it is on 916 cars.
Thanks Nige, after clamping a tempory earth to the column it works as it should.:thumbs:

Still puizzled as to how the meter reads properly when testing the relay's contact points in the fuse box though? Probably a good enough earth for the meter but not enough to operate the relay & therefore the horn.:confused:

Now to fix it properly.....?

Off to the mechanics as we speak.

Clive
 

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:thumbs: Glad the idea worked, be interesting to know where the link is on 916 cars.

A possible reason for the Meter readings is that a Meter takes very little current due to it's very high resistance whereas a Horn with its low resistance will draw about 6 Amps so a poor connection will " fail " when it tries to cope with this.

Good luck finding the problem Clive. :thumbs:

PS. Error in my original Post, should read " until you inserted the key and switched on ", and not " remove key. " Just edited so as to say what I meant to say and not to confuse any future visitors trying to fix a similar problem.
 

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Discussion Starter #11
Problem cured

Had an earthing wire fitted from the top of the gearbox to a clamp around the top power steering pipe, which runs along the bulkhead behind the engine. This is obviously connected to the steering rack which is in turn attached to the steering column & hey presto the column is now permanently earthed-problem solved:).

It could also be fitted from above rather than needing a ramp.

No one, & I asked some very knowledgeable Alfa people, could confirm where or how the steering column is originally earthed. I suspect it's from the steering lock/ignition housing which bolts to the main support bracket, somehow this has failed in this instance causing the wierd problem.

Clive
 

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I spoke to Chris about it and it wasn't something he'd heard of before, so thats a new one on us as well. Congrats on getting it sorted - hopefully it didn't cost you too much :thumbs:
 

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Discussion Starter #13
50p?

I spoke to Chris about it and it wasn't something he'd heard of before, so thats a new one on us as well. Congrats on getting it sorted - hopefully it didn't cost you too much :thumbs:
£10:)

Plus lots of my time.:(

Next time 5 minutes & approx 50p.:thumbs:

Clive
 

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:thumbs: Pleased that I was able to help.
 

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Thanks again Nige, you saved me at least another day of scratching my head!:)

Clive
:thumbs: No problem Clive.

I don't scratch my head any more, too much hair drops out !! :eek:
 
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