Horn and wipe screen problem

+ on F14 in BSI and - on metal?

I will try and take a picture

When I get to a suspected BSM fault (note BSM not BSI as they are very different) I just swap out the BSM.

It is quite easy to do and if you were going to open it up, you need to remove it anyway.

Swapping it out also means you don't add any extra faults to the board and they BSM is not designed to be user serviced.

Save a lot of time with a BSM swap out part (eBay) - scroll to find your version and one at the right price

I will replace BSI but I have to be 100% sure that it is a problem

Shomysss wrote: ↑Mon Jan 31, 2022 12:24 pm I will replace BSI but I have to be 100% sure that it is a problem

You can't do that easily.

You can only swap the BSM easily, the BSI is something more complicated to swap.

You should get 12V when the car is "awake" but I bet you get the same voltages as you did at the BSM.

Voltage is 1.5 (red pin on fuse F14 (on BSI) black on metal

Here is the circuit diagram for the horn. As you can see it shows an internal relay in the BSI powering the BSM.
My guess is that the relay contacts are bad.
Unfortunately this diagram does not show where the relay is getting it's power from, but I would assume that power is good otherwise more circuits would be affected.
If you have the skills the best way to go is to replace the relay.
The BSI has 2 circuit boards. one for the brains and the other for the relays. It is possible to remove the relay board from a "good" BSI and put it in your BSI.
When you pull the BSI apart, inspect the fuse F14 fuse holder, the solder joints and the PCB tracks.

I guess this one?????

Yes, that looks like the relay. It supplies power to F14, F15 and F7. It gets its power from F1.
F15 supplies power to the center display/clock. Is the center display playing up at all?

Is the center display playing up at all?

Display work properly

Have you checked the F14 fuse holder and solder joints?
Did you check both sides of fuse F14?
Do fuses F15 and F7 have good power when the car is "awake".
If the center display is good, it might not be the relay.