Horn got weak and AirBag light illuminated

[Aa892]

Hello guys,
I have been searching for almost 2 days for problems same as mine but couldn't find I hope I get help.
My cars is 2012 Mercedes SLK 200 1.8 Turbo R172
So I was driving and I pushed the horn hardly ( kinda punched it ) and after a few mins I pushed the horn again and it was sounding very weird and weak ( like hearing horn sound from a far ), I turned the car off and on again then I saw Airbag light came on with message (SYS malfunction please drive to workshop) and then I checked it with a scanner and the code ( B273513 ) code came with a message ( The squib for pyrofuse "onboard network line" has a malfunction, there is an open circuit ), please note that the same code came for SRS Airbag page and the Weight sensing system page on the Scanner ( shown in the attached pictures ), im no expert but I removed the steering wheel airbag and check to check the wires, and they were intact to their places, but I didnt check the clockspring as im no expert, i have also noticed that the seatbelt not bukled doesnt beep, if Im not wearing seatbelt it shows im not wearing but doesnt beeps to tell me wear the seatbelt my local mechanic is out of town so cant go to him until after 2 weeks when he returns, can anyone help me out? I suspect its the clock spring or maybe some fuse on the battery, any help will be appreciated.
Note: The steering wheel up and down lever was sometimes not working from before, sometimes it works and sometimes it doesnt, and its attached with the clock spring I think.

 

[LostKiwi]

Steering wheel up/down has nothing to do with clock spring unless the controls are on the wheel itself.
The clock spring is only used for any button on the steering wheel, the airbag and the steering angle sensor.
I would suggest you've damaged the airbag itself by hitting it hard. Not sure on the SLK but in most cars the clock spring is integrated into the steering angle sensor unit.

 

[Aa892]

Steering wheel up/down has nothing to do with clock spring unless the controls are on the wheel itself.
The clock spring is only used for any button on the steering wheel, the airbag and the steering angle sensor.
I would suggest you've damaged the airbag itself by hitting it hard. Not sure on the SLK but in most cars the clock spring is integrated into the steering angle sensor unit.

I removed the airbag and pushed the horn but it was still sound weird and weak, and the wheel up/down is integrated with the clock spring I think as I saw it in a diagram but not sure

 

[LostKiwi]

I removed the airbag and pushed the horn but it was still sound weird and weak, and the wheel up/down is integrated with the clock spring I think as I saw it in a diagram but not sure

Is the wheel up/down control mounted on the column or the steering wheel? Both cars I have with electrically adjustable steering wheel position it's mounted on the column.

 

[Aa892]

Is the wheel up/down control mounted on the column or the steering wheel? Both cars I have with electrically adjustable steering wheel position it's mounted on the column.

Its on the column as shown in the picture

 

[LostKiwi]

Its on the column as shown in the picture

In which case it won't use the clock spring.

 

[Flyinspanner]

Check the Earth in your horn?

 

[Aa892]

Check the Earth in your horn?

How to check?

 

[Flyinspanner]

Two wires go to your horn, one is the positive supply, one is the Earth. Use a multimeter to check the Earth isn’t high resistance. If it is, trace the earthing point and clean it up.

You could make up fly leads and try the horn directly off the battery to check that it isn’t faulty.