horn problems, Diagnosis needed

[cooa99]

Hi all,

My Horn stopped working recently on my E53 3.0d sports

Here are the fault testing that I have done so far.

1) The 2 horns work when powered from the battery
2) While my daughter pressed the horn I connected a circuit tester in the bonnet to the wires going to the horn but tester does not light up
3) I checked the fuse box in the glove box to confirm presence of 12v supply. Also tested the 2 top ends of the 15A fuse and can confirm 12v presence
4) Took the glove box out to get to the back of the fuse box where the horn & fuel pump relays are situated. swapped the fuel pump relay with the horn relay and the horn still does not sound at all.

So this leaves me with the sports steering wheel as the only place left to check. Are there any precautions that i need to take since this is where the airbag is situated? Not sure what exactly I will be testing here....?

Also does the horn work only with the engine tuning or also with the keys in the accessory & On position? ...never paid attention to this

help really appreciated

Thanks

[Qsilver7]

The horn only works when the ignition is on...but I can't remember if it is KL R (iggy position 1) or KL 15 (iggy position 2). I do know that the engine does NOT have to be running in order for the horn to work...but it does have to at least be in either the 1st or 2nd iggy position.

[cooa99]

thanks regarding the position. I was turning to position 2 for tests ..

I bought a new relay today so will be putting that in. If that does not work then issue has to be somewhere on the steering wheel?

[Qsilver7]

Originally Posted by cooa99

thanks regarding the position. I was turning to position 2 for tests ..

I bought a new relay today so will be putting that in. If that does not work then issue has to be somewhere on the steering wheel?

The steering wheel would be the next place I'd check if I were in your situation...that is if the new relay doesn't work.

The horn has its own connection on your side of the steering wheel (behind the air bag) that then runs to the slip ring. From there, the wiring goes through the slip ring...then from the backside of the steering wheel/slip ring to the wiring connections below the dash.

Unfortunately, I only have images of the single stage airbag and steering wheel/slip ring set-up...but the wiring should be similar for your dual stage set-up:

{in pic below, the horn's wire is the single blue one...with the orange colored protective cover where it connects to the horn (on the back side of the air bag)...and runs to the slip ring}


{the pic below is the back side of the steering wheel/slip ring and you can see the horn's blue wire in the wiring harness bundle as it exits the slip ring}


{the pic below shows the horn's blue wire (on the far left) plugged into the connector below the steering column/dash}

[wpoll]

I'd agree that the it's time to take off the steering wheel. Disconnect the battery first, unless you have the tools to reset SRS errors.

Great pics, Qsilver7 - shows the likely fault areas well.

I hope you not are looking at a failure in the clockspring/slip rings. I recently helped a friend diagnose and fix that failure - quite a journey. About two years ago he got an SRS warning light. Got a local auto-electrician (that claims to specialise in SRS repairs) to read the codes - drivers airbag impedance high. Seesm like a straight forward fault description, but oh no, he claims its a dead SRS module. So over $1200 later in parts and labour, it's "fixed". No SRS light. For a week. Then it came back. He takes the car back and a day later claims it is again, "fixed". He has put the original SRS module back in, mutters something about it being a different issue. So my friend now has a spare SRS module. Car is fine for nearly two years then bing! - SRS warning is back. At the same time, the cruise control packs up. He calls me and I say "clockspring". He orders a new one, installs it, gets SRS error cleared and everything is working well. Out of curiosity, we pulled the old clockspring apart... and are greeted by a very shonky attempt at repairing the clock spring - what is likely to be the original fault site.

[cooa99]

Thank you Qsilver7 and wpoll !.

I took the airbag off the steering wheel and gave the other plugs a good shake and also blew some dust away. Then Put everything back together again feeling defeated

Connected the battery and pressed the horn. Beautiful music to my ears, IT WORKED!

Not sure what i did there ..... may be a loose connection afterral?

I am over the moon

[wpoll]

Great result! And thanks for updating the thread.

[Qsilver7]

GREAT!!! Glad the issue was resolved...and thanks for posting back the results.

[zzzzkev]

Anybody know where the actual horns are located? There are two. One of mine has decided to be intermittent. Sounds like a sorry little car when it does not sound with the other one. I'm thinking it's probably corrosion on the connection to the horn versus any of the diagnostics done here. I honestly don't know where to look for them! I tried my Bentley's manual. The only mention describes somewhat the diagnosis described by Qsilver7 and WPoll in their thread with cooa99.

[wpoll]

Originally Posted by zzzzkev

Anybody know where the actual horns are located? There are two. One of mine has decided to be intermittent. Sounds like a sorry little car when it does not sound with the other one. I'm thinking it's probably corrosion on the connection to the horn versus any of the diagnostics done here. I honestly don't know where to look for them! I tried my Bentley's manual. The only mention describes somewhat the diagnosis described by Qsilver7 and WPoll in their thread with cooa99.

Both horns (left/H2 and right/H3) are in the left wheelhouse...



You can see them if you look way down in behind the left side headlight...