How to fix your horn problem - Alfa Romeo Forum
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(Post Link) post #1 of 2 Old 09-07-12 Thread Starter
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How to fix your horn problem

Hi, i bought a selespeed 2 weeks ago and put on a tow bar and fixed a lot of problems with it.

I'm not a mechanic but used this forum for help and managed to do it all myself saving a lot of money so thanks to everyone that posts on here.

Although i had some difficult problems one that eluded me for some time was the horn not working. It seemed a common problem and there was a lot of information on here but in the end i got lucky as everthing that was suggested on the forum didnt work.

To make life easier for anyone else with a horn problem i thought i'd list the easiest procedure for fixing your horn. Please note this is for a TS selespeed 1999 auto. The proceedure should be the same for most but some things may be located in different places for different models so if in doubt check your owners manual.

1. Replace the fuse (less than 1)
Remove the cover to the main fuse box located to the right of the steering wheel. The horn fuse is the bottom left fuse and should be yellow (20 amp). Pull it out and replace it with a new one (there are spare fuses running down the right side of the fuse box so you can use one of these but please remember to replace them as you may need for a future emergency).

Try the horn.... still not working?

2. Replace the relay (less than 3)
Yes you have a horn relay and this is what was wrong with my horn. If you hear a clicking sound coming from the fuse box as you press the horn - then you know one thing for sure -the horn on the steering wheel and the wires to and from the steering wheel and the fuse box work fine. Even if you do hear the clicking sound this DOES NOT mean the relay works - it only means ONE CONNECTION of the relay works - so sound or no sound i strongly recommend replacing the horn relay..... here's how it is done.

The horn relay is a small black box with 4 pins that slide into the back of the fuse box. Its not easy to access but i managed it ok - for some it might be easier to unbolt the fuse box.

Here's how to do it without removing the fuse box. If you can get you head in above the pedals looking up you will see the back of the fuse box. Top left there are 2 yellow relays - next to them is the small black relay (top right).

If you are unable to get your head in then try this - look at the fuse box from the front put your hand behind the fuse box to the top left (not top right as you are looking from the front not the back). If you here a clicking noise when pressing the horn the keep pressing it as the relay with vibrate and make it easier to find. When you have your finger on the relay trace your finger around the corners - there should only be a relay to the right of it (none on the left).

IMPORTANT: If you are not unbolting the fuse box and are removing the relay by sight or feeling around behind the fuse box REMEMBER THE POSITION OF THE PINS AS YOU REMOVE THE RELAY or you will be mucking around forever trying to put in the new one.

Once you have located the relay you need to pull it out. It can be a bit stiff and a wriggle as you pull will do the trick. Once removed put the new one in.

Try the horn.... still not working?

3. Check the horn under the hood of the car

This is easy. Get a wire long enough to go from the positive on the battery to the horn (there are 2 horns located around the front right wheel arch). Both horns have purple and black wires connecting them. The purple wires come from the relay and are live when the horn is pressed. The black wires are earth / negative.

To test if the horns work connect one end of your long wire to the positive on the car battery. Then briefly touch the horn connectors with the purple wires with the other end of the wire you attached to the battery. If the horn sounds then you know they work ok and they are not the problem.

If the horns dont sound then try running another wire from the connector with the black lead to a suitable earth on the car before testing again as it may be the horns are poorly earthed. If the horns are still not sounding then replace the horns - they dont work.

Try the horn.... still not working?

4. Check and replacing the horn on the steering wheel (15 second hand)

You have a few options here depending on how good you are with electrics. I recommend getting a spare steering wheel from a brakers yard (confirm with the yard the curcuit board hasnt already been removed from the wheel as you may need it. confirm it is the exact steering wheel for your car).

OK. Before you begin press the horn - if there is NO CLICKING noise from the horn relay behind the fuse box then continue on.

If you hear a clicking noise then nothing is wrong with the steering wheel or horn on the steering wheel so no need to continue - you need to check the wiring from the horn under the hood to the relay (its purple and will probably need replacing or fiixing somewhere along the line).

OK so now you can either replace the steering wheel with the one that doesnt work or if you want to keep your steering wheel you can replace the broken parts with the ones from the steering wheel you got from the brakers yard. To do this please be very careful as the horn has an air bag with EXPLOSIVES so please work with extreme caution.

There are 2 areas you need to look at if you are keeping your steering wheel as one of these will probably be your problem. One is the springs between the horn and the curcuit board with in the steering wheel -one or more might be broken. The other area to look at is a broken connection on the curcuit board itself. The best thing to do is to replace the curcuit board and put the steering wheel together again ensuring all the springs are ok (if they arent just replace them with the ones from the brakers yard.)

I suggest dismantling the steering wheel from the brakers yard first as you will need the parts and its good practice for when you are working on your steering wheel.

First you need to remove the air bag - there are 2 holes at the back of the wheel - you need an allen key to do this. Then simply disconnect the wires going to the air bag by pulling them off.

You now have a plate held on by 4 screws with springs behind them. Remove the screws and the plate will come off after you have either cut or disconnected the wire to it. The metal plate is the connector for the horn. The springs keep it off the curcuit board. As you press the horn the metal plate goes down on the springs and creates a connection on the curcuit board that sounds the horn. If the springs are broken or the metal plate wasnt able to touch the curcuit board then all you need to do is replace the plate, screws and springs. If this all looks good you will need to remove the curcuit board too and replace that as well.

Once, these parts are replaced you can test your horn before putting on the air bag by pressing down on the metal plate - remember to attach the wire to it first or it wont work.


Last edited by globetrotta; 09-07-12 at 12:24.
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