Fix horn and air bag light on

[JPB]

Hey all,
Z4 3.0si 2006 E85 here and my horn's stopped working and the airbag light has come on the dash. I've tried several fixes as listed on this forum but to no avail. Any other fixes / tests you'd recommend before I take it to the garage?

Symptoms: no horn, clicking behind fuse box in glove box when horn depressed on steering wheel. Air bag light on dash.

Things I've tried:
1. Tested fuses 14 and 37 in fuse board behind glovebox with multimeter (they were fine) and removed/reseated them.

2. Removed fuse board behind glovebox and removed/reseated all the connections at the back in case they were loose. Also inspected each wire and connector inside the plug heads for corrosion or breaks.

3. Tested every blade fuse in fuse box behind glovebox with multimeter.

4. Tested every blade fuse in the vertically mounted black fuse box inside the engine bay (passengers side) behind what I think is the shock absorber mount.

Things I haven't tested:
- Hooking the horn itself set up to a battery (I don't know where it/they is/are, or how to test it).

- Code checker on Carly or similar.

Many thanks in advance,
Jase

 

[enuff_zed]

There are two horns, fitted one each side behind the fog lights. Accessible through the wheel arch liner panels. Sounds like one of yours died a while back and now the other one has as well.
The horn is mounted on a bracket with a single nut holding it. Easiest answer is to unbolt the horn from the car and then rest the rear mounting on one terminal of a battery and use a jumper lead from the other terminal to the connector on the side of it.

Airbag light needs codes read before we can work out which of many issues it may be.

 

[colb]

Might be a good idea to update your user details to show your location, help may be close to you.
Airbag light needs a code reader to see what code has set to bring it on to pinpoint the problem.
Horns need checking to see if they are getting power when horn is pressed, if not trace wiring back to their relay and fuses.

 

[Umfaan]

Horns are a common problem on E85/86…they don’t have a long life expectancy…probably where you should have started first

 

[TriggerFish]

My guess would be steering wheel/slip ring wiring, as that's the commonality between the two parts... (Assuming both started around the same time. You'd obviously notice the airbag right away, even if you don't use the horn too often)

If you can jump the horn relay and it works, I'd be even more confident in my guess.

Edit - do you have steering wheel buttons? Do they work if so? There is an earth in the steering wheel which is just a push spade connector - maybe it's something simple like that having come off (although that might be for mfsw only, I'm not sure)

 

[enuff_zed]

My guess would be steering wheel/slip ring wiring, as that's the commonality between the two parts... (Assuming both started around the same time. You'd obviously notice the airbag right away, even if you don't use the horn too often)

If you can jump the horn relay and it works, I'd be even more confident in my guess.

Edit - do you have steering wheel buttons? Do they work if so? There is an earth in the steering wheel which is just a push spade connector - maybe it's something simple like that having come off (although that might be for mfsw only, I'm not sure)

But he does say he can hear the horn relay clicking?

 

[JPB]

Update: I've inspected behind the wheel arch liners behind the bonnet but I can't identify where the horns are. I've also inspected in that area under the bonnet but can only really see the back of the main headlight casings. I'll do some more looking later to see if I can find them. Horns seem to be £20 for the pair online so hoping it's a cheap and quick fix but I might have to jack up and take off the wheel to get a better look inside.

Going to order up an obd reader too, for the airbag light as suggested.

Thanks for the feedback so far!

 

[TriggerFish]

But he does say he can hear the horn relay clicking?

Good spot - I totally miss that line

 

[enuff_zed]

Update: I've inspected behind the wheel arch liners behind the bonnet but I can't identify where the horns are. I've also inspected in that area under the bonnet but can only really see the back of the main headlight casings. I'll do some more looking later to see if I can find them. Horns seem to be £20 for the pair online so hoping it's a cheap and quick fix but I might have to jack up and take off the wheel to get a better look inside.

Going to order up an obd reader too, for the airbag light as suggested.

Thanks for the feedback so far!

There are two access panels in the wheel arch liners. you need to be looking through the lower one.
Take a look at the photo in this wanted add and you'll see the left horn.
https://z4-forum.com/forum/viewtopic.php?t=150531

 

[JPB]

Update: I've inspected behind the wheel arch liners behind the bonnet but I can't identify where the horns are. I've also inspected in that area under the bonnet but can only really see the back of the main headlight casings. I'll do some more looking later to see if I can find them. Horns seem to be £20 for the pair online so hoping it's a cheap and quick fix but I might have to jack up and take off the wheel to get a better look inside.

Going to order up an obd reader too, for the airbag light as suggested.

Thanks for the feedback so far!

There are two access panels in the wheel arch liners. you need to be looking through the lower one.
Take a look at the photo in this wanted add and you'll see the left horn.
https://z4-forum.com/forum/viewtopic.php?t=150531

Thank you! I did look at that thread before but didn't quite see it until I studied it closer. I was expecting it to be mounted vertically but it seems to be horizontal. I looked through the bottom panel earlier so I'll take another look this evening.

 

[JPB]

Okay after some more looking it was the wire connection behind the steering wheel for both that was broken. All fine now and didn't need to replace any horns or fuses!

 

[Ratrace2222]

Wire connection behind the steering wheel .... can you elaborate? Mine has the exact same issue you are describing.

 

[Gebbly]

Looks like the car horn gremlins are on the rampage. Just had my Z4M serviced and they noticed the horn isnt working. As described above, when I press the horn on the steering wheel I can hear a click from the fuse panel behind the glove box.
I am a complete newbie at car mechanics but I would really like to learn. Could anyone offer advice to an absolute beginner on how I go about diagnosing this please?

I understand I need to trace the fault and if I had easy access to everything on a bench I would start at one end and work along but given the cramped confines I'm thinking I start at the easiest access point and work from there?

[ref]TriggerFish[/ref], suggests trying to "jump the horn relay". If that is near the fuse panel behind the glovebox then that is probably the easiest place to access isnt it? Could someone elaborate this "jumping" please? Would it mean removing the relay and replacing it with connections to a DC power supply to send power direct to the horn? Or perhaps I could remove fuse 37 and connect my power supply to it to send voltage to the horn?

Reading the above information it sounds like another thing I should do is get access to the actual horn and try connecting it up to my lab power supply and see if that works. Several people have mentioned the horns being behind the wheel arch linings. Should I be able to access without removing the wheel? Or am I looking at jacking the car, removing the wheel and actually removing the arch liner to get access? I have some spare connectors of the correct type (for another project) so perhaps I can plug one of those in to the horn with long wires and then use that to connect to the power supply without removing the horn?

 

[enuff_zed]

Looks like the car horn gremlins are on the rampage. Just had my Z4M serviced and they noticed the horn isnt working. As described above, when I press the horn on the steering wheel I can hear a click from the fuse panel behind the glove box.
I am a complete newbie at car mechanics but I would really like to learn. Could anyone offer advice to an absolute beginner on how I go about diagnosing this please?

I understand I need to trace the fault and if I had easy access to everything on a bench I would start at one end and work along but given the cramped confines I'm thinking I start at the easiest access point and work from there?

[ref]TriggerFish[/ref], suggests trying to "jump the horn relay". If that is near the fuse panel behind the glovebox then that is probably the easiest place to access isnt it? Could someone elaborate this "jumping" please? Would it mean removing the relay and replacing it with connections to a DC power supply to send power direct to the horn? Or perhaps I could remove fuse 37 and connect my power supply to it to send voltage to the horn?

Reading the above information it sounds like another thing I should do is get access to the actual horn and try connecting it up to my lab power supply and see if that works. Several people have mentioned the horns being behind the wheel arch linings. Should I be able to access without removing the wheel? Or am I looking at jacking the car, removing the wheel and actually removing the arch liner to get access? I have some spare connectors of the correct type (for another project) so perhaps I can plug one of those in to the horn with long wires and then use that to connect to the power supply without removing the horn?

Don't overthink it! 9 times out of 10 its the actual horn failed. You've probably only had one working for a while and now that has died too.
Speak to one of the lads who break zeds, get a High and a Low horn and swap them over.

 

[TriggerFish]

Here is the horn relative to the lower access panel. You could probably squeeze a hand on there to disconnect the plug and connect a multimeter to the pins and check for 12v, before buying anything



Although the pins are thin, so may be hard to probe...

 

[Gebbly]

Thanks [ref]enuff_zed[/ref] and [ref]TriggerFish[/ref], I guess first port of call is testing the actual horn then. I think I have a spare one of those connectors both male and female so I can plug them to either of the car connectors and with 2 exposed wires that will make it easier to test. Is access to that panel possible without removing the wheel and just putting it on hard lock? Guess I have a job for this weekend.

 

[TriggerFish]

I couldn't tell you about access - the front of mine is on ramps, so I can't turn the wheel to test I'm afraid. You might find lifting the car (but keeping the wheel on) helps if access is tight, as it'll move through curve of the wheel relative to the access panel.

Good luck though, sounds like you've got the right, methodical approach!