Should be simple! But isn't! Need help with E61 horn. Aarrgh!

Not sure where to post this, but some help from the hive is needed, because this is driving me crazy.

2006 E61 – BMW 530Xi Wagon (The Mrs cruiser, aka "The Mother Ship")

• Horn isn’t working.

• No warning lights, no messages, all the buttons in the steering wheel works, as well as heat in steering wheel.

• No blown fuses. The car has 2 fuse boxes (one in trunk and one in glove box) and the internet isn’t completely unanimous on which fuse is for the horn. I’ve checked every 5A fuse in the car – all good.

• BMW connectors makes measuring power at horns tricky, but I managed to get a 8V (??) reading while having the horn button taped down. Could be measuring wrong (confused…)

• Spent $35 on a used ebay horn. Hooked it up – no go.

• To my best knowledge, the car doesn’t have a horn relay.

• Had the steering wheel apart to check all connectors. All looks good, nothing loose. Connection points for horn button (which is the airbag casing) are clean.

What. Am. I. Missing?!

Old German Car disease.  Take a 5 amp fuse from another spot in the fusebox and swap it with the 5 amp fuse that the horn works.  See if the horn works now.

Sounds crazy, works all the time. I can't explain it, as the fuse is fine but my old M3 would do this all the time and swapping the fuses around fixed it every single time.

soy-based wiring insulation.   suck it, Klaus!

In reply to docwyte :

That sounds absolutely insane. Don't get me wrong, I'm grateful for the advice and will certainly try it... but it sounds insane.

I'll report back this evening.

Unplug at steering column switch cluster.  Check for power in on red/blue wire, pin 2.  Use a larger bulb that will load the circuit more heavily than a multimeter, and ground it to wire 1. That will confirm ground integrity too.  Jump wire 2 to wire 3, left horn blows.  Jump wire 2 to wire 4, right horn blows.   No toot, either fuse, wire or horns are boogered.   If you have toots, plug stuff back in, and cross wires 5 and 6.  Toots?  You need a clockspring or switch.  No toots?   Order a new steering column switch cluster, whatever the hell that is.

In reply to Streetwiseguy :

Thank you for the diagram! Perfect! 

Now, my car is a 2006. Not sure how to read the diagram: Is there no "Electric Steering wheel module" in my car or is it just that the wires have different colors? 

Also, my car doesn't have a "left and right" horn. They are both in the right/passenger wheel well, behind the bumper. 

Left and right is probably just the mounting - it's not important. As to the module, you may just have to trace some wires - look at the steering column switch cluster as shown and see what's coming into it.

Progress! 

OK, when I hotwire the horn in the steering wheel, it toots.

When I push the little soft buttons on the back of the airbag module, it toots. 

When I snap the airbag module back into place, it doesn't toot. *sad face*

I have a mechanical issue in the movement of the airbag module in my steering wheel!

FIXED! WIN! 

Big thank you!