[Fx82]

I installed hud into an E71. It works perfectly except for one thing and that is the most bus.
I use this 3 meter y adapter (random picure from google) :


I've installed this adapter on the back of the cic unit. I've removed the most cable on the quadlock and inserted into the y adapter. The plug of the y adapter now goes into the cic.
When I do this there isn't any sound from the amp.
When checking the car for error codes the most bus is in tact. I've saved the most configuration. The next day when I check the car again with ista it marks the combox and amp red. When I remove the y adapter amp and combox are working fine.
What is going on here?
How can this be solved?

It is always headache when working on the most bus

[SweetBMW]

Check for proper light direction and that you have power to Hud. (Light coming from Hud connectorcwith ifnition on)

[Fx82]

I double checked that and there is light coming from the most plug of the hud.

What direction do you mean or just that there is a light coming from it?

[SweetBMW]

The hud will always output light at the correct port. But check that “out” from headunit goes to in on the next unit. And out from that goes to in on the next and so on.

[Fx82]

You mean to check if there is red light coming from all the modules on the most bus?

[larshutten]

What sweetbmw means is that on the most connectors are arrows in and out make sure that is set right. Also I believe that HUD should be first in row on most bus. But I can be wrong with that.

[Fx82]

You mean that the arrow is on the small plug?

[SweetBMW]

Yes on the small piece

[Fx82]

Ok I'll have a look at that.

[Fx82]

I've checked it and the most hub has to be rearranged. I can'that find a good document on how this actually works and how the ring is closed.
The car already has a Y adapter now it will have 2.
I did noticed that the arrow on the most plug is on the out arrow.

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Fixed just add the 2nd y adapter where the first is and make sure it is on input.