lukespalding said:

Ok yea I'll try that, but one question thought how the heck does the relay physically move and connect to complete the circuit because you dont actually push anything in the relay do you? so how does it actually activate when the horns pressed..?

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In simple terms, a relay is an electromagnet (a coil of wire with a steel core) and a pair of contacts. Passing current through the coil causes the core to magnetise and attract another bit of metal called the armature which has the contacts mounted on it. The contacts complete the circuit that you are controlling. The reason for using a relay is primarily so that a small control current (for the coil) can control a large current (through the contacts).

Bigger versions of relays are sometimes called solenoids (e.g. the one inside a starter motor). In industry, big relays are called contactors.

red.

lukespalding said:

Ok good point. So when I "earth" the wire I'm basically doing what the horn push would be doing.

Dude I'm actually starting to understand this bloody circuit......

Luke

Click to expand...

Spot on.

red said:

In simple terms, a relay is an electromagnet (a coil of wire with a steel core) and a pair of contacts. Passing current through the coil causes the core to magnetise and attract another bit of metal called the armature which has the contacts mounted on it. The contacts complete the circuit that you are controlling. The reason for using a relay is primarily so that a small control current (for the coil) can control a large current (through the contacts).

Bigger versions of relays are sometimes called solenoids (e.g. the one inside a starter motor). In industry, big relays are called contactors.

red.

Click to expand...

first attempt:
from the relay to the horn thats a live circuit(?) which hasn't got a completed earth so it doesnt work until there is one. so when you puch the horn the negative circuit is complete and then the relay fires up and connects which then gives the horn circuit a earth so then it sounds?
erm think that's right, hope so my brains melting lmao

second attempt:
ok been reading thru it all again so the horn push 1 side is earthed and 1 side goes to the relay. now the relay 1 side is live(12v) and the other is the earth wire but isnt earthed until the horn is pushed. then from the relay to the horn there is 1 live wire(?) and 1 earthed wire but isnt actually earthed until the horn is pushed.. yea? no?

so switched negative is a negative circuit which has a switch in it that needs to be activated to complete the negative circuit. yea?

Luke

lukespalding said:

So from the relay to the horn push thats a broken earth circuit(negative circuit) which is complete when the horn is pushed, correct?

then from the relay to the horn thats a live circuit(?) which hasn't got a completed earth so it doesnt work until there is one. so when you puch the horn the negative circuit is complete and then the relay fires up and connects which then gives the horn circuit a earth so then it sounds?
erm think that's right, hope so my brains melting lmao

Luke

Click to expand...

Luke,

You understand the primary "broken earth" circuit fine (though as I say, it is technically called a "switched negative" circuit).

For the secondary circuit (relay to horn) you are almost right. You correctly identified it as a "live circuit". Technically it is called a "switched positive" circuit, which means that the switch comes before the load (the horn). The relay contact switches the 12V positive supply on to the horn and the horn has a permanent earth.

So, to summarise:

"Switched Positive" means the circuit is Battery - Switch (applies 12V) - Load - Earth
"Switched Negative" means the circuit is Battery - Load - Switch (applies 0V) - Earth

Try to think of the complete horn circuit as two separate circuits, primary and secondary.

The primary circuit (relay/horn push) is switched negative, the load is the relay coil and the switch is the horn push.

The secondary circuit (relay/horn) is switched positive, the switch is the relay contact and the load is the horn.

red

ok i seriosuly think ive got it now

first circuit - switched negative:
earth point-earth wire-to one side of horn push-horn button- then the earth wire from horn push to the relay press the horn and it completes the switched negative circuit. creating and earth for the relay.

second circuit - switched positive:
the relay has a live feed but stays at the relay and when the horn is push the relay has a earth, the relay then sends the 12v down to the horn and cause the relay is now earthed the horn sounds.

Ok i honestly think I have got the switched negative circuit down, I get the switched positive one i think but hard to explain.

Luke

lukespalding said:

ok i seriosuly think ive got it now

first circuit - switched negative:
earth point-earth wire-to one side of horn push-horn button- then the earth wire from horn push to the relay press the horn and it completes the switched negative circuit. creating and earth for the relay.

second circuit - switched positive:
from relay to horn there is a live circuit which is incomplete and is completed when the relay gets a negative feed, which then allows the horn to sound.

Ok i honestly think I have got the switched negative circuit down, I get the switched positive one i think but hard to explain.

Luke

Click to expand...

Luke,

I think you've got it. On the secondary circuit, remember to think of the relay as having two parts - coil and contact. The negative from the horn push is energising the coil, which makes the contacts close. The contact is then switching the positive on for the horn. Inside the relay the contacts are insulated from the coil. The negative from the horn push does not go anywhere near the contacts.

I think that'll do for tonight! I'll try to catch up again tomorrow.

red.

OMG I think I've got it... I'll check it tomorrow and report back with my findings thankyou so much Red.

Cheers

Luke

Hi guys well sorry for not replying yesterday, was raining so didn't check the car out but have done so today and I've attached the pictures. I did try and upload into my gallery but it wouldn't find any pictures on my computer even though it takes JPEG's and they are JPEG's lol :/

Well anyway as you can see the horn wire isn't even attached to the plug that the airbag is attached too. It's totally snapped at the plug, now I dont know if the cable is tight in there and cause I got road rage a few times and hurt the horn(LOL) maybe that snapped it(?) Dont really now tbh but anyway any idea's how to fix it?
Get a new cable? or...? any ideas? How can you take the plug out anyway just so I dont break anything else

Cheers

Luke

You can buy crimp connectors from auto electric suppliers or even places like Maplins or Tandy. Google found these folks http://www.autoelectricsupplies.co.uk/?s=16389

Soldering also works but tracks down the wire strands so the copper eventually breaks where the solder ends. Don't over do it and the joint must be well supported with heat shrink sleeve.

Thanks for the pix. That yellow cable is the one that's missing from my steering wheel. I can only assume someone lost it amongst the steering column cables, but now I know what to search for. Yippee

WhiteSei said:

You can buy crimp connectors from auto electric suppliers or even places like Maplins or Tandy. Google found these folks http://www.autoelectricsupplies.co.uk/?s=16389

Soldering also works but tracks down the wire strands so the copper eventually breaks where the solder ends. Don't over do it and the joint must be well supported with heat shrink sleeve.

Thanks for the pix. That yellow cable is the one that's missing from my steering wheel. I can only assume someone lost it amongst the steering column cables, but now I know what to search for. Yippee

Click to expand...

That yellow cable goes to airbag... :O you driving with no airbag lol

cheers for the link and info. Have i got to take my steering wheel off to get to the that wiring?

Luke

You just need to reconnect the horn wire to the horn push that sits with the airbag.

Certainly the airbag needs sorting but its I'm not overly panicked about it. My previous day to day transport was a 900cc bike which has no air bag, no seatbelt, no ABS, goes like stink and falls over when I dont put my foot down.

WhiteSei said:

You just need to reconnect the horn wire to the horn push that sits with the airbag.

Certainly the airbag needs sorting but its I'm not overly panicked about it. My previous day to day transport was a 900cc bike which has no air bag, no seatbelt, no ABS, goes like stink and falls over when I dont put my foot down.

Click to expand...

yea but I cant really get to the wire inside the steering wheel and not sure how i'd get the plug(?) out to fix it.

good point and LOL ye that tends to happend when u try foot-less stopping.

Luke,

Looks like you'll need to take the wheel off. Just be careful not to turn the clockspring while the wheel isn't there. I think the point where the wires are broken off is the plug that goes into the clockspring (4-way). Unless you can somehow join the wires on again, you might have to get a replacement part. Is the other end of the black wire permanently attached to the horn push or is it on a plug? Just wondering whether you can replace just the cable. If you need cable plus other parts it would be much cheaper to go to a scrapyard than to buy new from a main dealer.

red

red said:

Luke,

Looks like you'll need to take the wheel off. Just be careful not to turn the clockspring while the wheel isn't there. I think the point where the wires are broken off is the plug that goes into the clockspring (4-way). Unless you can somehow join the wires on again, you might have to get a replacement part. Is the other end of the black wire permanently attached to the horn push or is it on a plug? Just wondering whether you can replace just the cable. If you need cable plus other parts it would be much cheaper to go to a scrapyard than to buy new from a main dealer.

red

Click to expand...

The horn wire that's broke does come out of the horn push plug but I wasn't sure on how to get the other plug out that's connected to the clockspring.. read my haynes and it seems I do infact have to take steering wheel off. So if I do manage to get the plug out I'll either give it ago at fixing or just nip to a scrappy and whip a wheel off Haynes said to use tape to secure the clockspring so it doesn't move while the wheel is off..reckon that's a good idea Red?

Edit: That's if there is a plug connected to the clockspring or if its perm connect to the clockspring which means I'll need a new clockspring -.-

Luke