[Dutchsea]

For a while now, my radio on my 2006 320d has only been receiving a limited number (3) of radio stations.
After some research it turns out that the cause of the e9x is often a defective diversity antenna amplifier.

I measured my module and found that pin 1 (lower black/red wire) of the power cable does not produce any voltage, while apparently there should be 12 volts there (photo 1).



I also checked fuses 5 and 19 and they are both fine and I measure 12 volts. I may need to check other fuses, but based on the overview of fuses (photo 2) I think I measured the right ones.



Where could the problem be?

Does pin 1 receive voltage from the diversity module? If so, that module probably is no longer good.
Or does the module receive voltage via pin 1 from the battery? If this is the case, there may be a broken wire somewhere.

I don't have a diagram to check where I can measure this wire.

Who can advise my next step?

[sabino56]

Well, "advise" would be too strong of a word. I tried and failed to fix similar problems on mine but can share what I know/think I know. Assume some of below is wrong/mis-directed. I'm not an expert on this. It was also many years ago so I don't remember all.

Here is post where I asked questions on similar w/o a response.
https://www.e90post.com/forums/showthread.php?t=1888027

I have a 2006 E90. Similarly, at some point my radio reception became poor. There is a signal strength test you can run on the radio and it showed I had poor signal strength. I don't recall how to do it but it some combination of button push or holds or menu item.

There are a set of "BMW Training" pdfs floating around. One of them is "#8 Entertainment Systems" which has some helpful info. I think ctuna may have posted them? not sure.

TIS has some schematics if you can get access to it. I found it helpful but also sometimes apparently contradictory, at least the online one. I've not installed or have access to ISTA.

On my car, the power comes from Fuse 2 to pin 4 on connector X1143. The diversity antenna is apparently enabled with a RAD_ON signal from the radio.
What I found for the X1143 connector on the diversity antenna is
1 - Comfort access BL/YEL
2 - GND
3 - RAD_ON Blk
4 - PWR Red/Brn
5
6 - CAS BLu/Rd

In my case, I was getting a code ABCC - short circuit to diversity aerial. It didn't show up as dash light but I could read it with DIS. I would never see it with INPA. So, unless you had DIS or access to someone who was knowledgable on this, newer diags - you may not see the ABCC code. Or perhaps that was false code on DIS and they fixed that with later version - don't know.

In any event, even if I reset the error the radio didn't work better so not sure it was a real error or not. I also could not find info on what was be tested with that ABCC code - was it the RAD_ON line or some diversity antenna internal check? I could confirm power to the antenna but just had voltmeter and could not tell if RAD_ON was working.

I got to point where I decided I needed either/or/all
- access to ISTA with hopefully better diagnostics and troubleshooting
- an oscilloscope to probe the RAD_ON in an attempt to understand if it was working
- pull the radio and check continuity between connectors of the RAD_ON

I did try a eBay salvage yard diversity antenna with same PN as mine - it looked in good shape, no obvious water, etc. It did not improve the reception.

At that point, time to work on it further got short and I got used to no morning radio so... it's been on the "want to do list" for a long time but haven't work it for years. If you have specific questions on PNs/circuits - I collected some pdfs and notes and perhaps I can help or misdirect.
Good Luck. I'd be interested in what you find.

[Dutchsea]

Thank you for your elaborate reply. Based on your message I learned some interesting new stuff. Suggest you check the message on the uk bimmer forum too:

https://www.bimmerforums.co.uk/threa...-cable.587564/

Shame bye the way that the website www.newtis.info has been shutdown…

I don’t get any error messages from DIS 57 nor from Bimmerlink

Seems in my case pin 1 of the x1143 connector doesn’t get power when the radio is turned on. Could be a broken wire. Most likely in the rubber sleeve connecting the chassis to the tailgate. I am going to check this.

My pins are most likely connected like this (from bottom to top of connector x1143):

1 - Power supply 11-12v (RAD_ON)
2 - NC
3 - Signals from remote control receiver to CAS 5v
4 - NC
5 - signal from CA (Comfort Access) control unit to remote control receiver 5v
6 - Power supply for remote control receiver 12v - terminal 30 - probably fuse 63 in junction box

Other reasons for bad reception may be broken grounding straps / bonding straps in the tailgate. Most of mine are broken. But I still have grounding one my diversity antenna amplifier module so I guess at least one is still good.

Bye the way, the grounding of the diversity antenna amplifier module goes through the 2 bolts that connects the module to the tailgate, not through the x1143 connector. At least on my model.

Another option that I have read about is that the antenna in the rear window and or in the spoiler has gone bad. Especially the one in the window can deteriorate.

Anyway, more to investigate. I will report back when I did some more checking.

[gbalthrop]

Originally Posted by Dutchsea

... my radio on my 2006 320d has only been receiving a limited number (3) of radio stations... I measured my module
and found that pin 1 (lower black/red wire) of the power cable does not produce any voltage, while apparently there
should be 12 volts there (photo 1).

Attached are ISTA ScreenPrints of the Aerial diversity circuit for Radio Reception and Remote Control (Locking signal).
If your Remote Control Locks/Unlocks doors, likely the Aerial diversity unit is OK and you have wiring issue re Antenna.
As suggested, E91 models have reported issues with broken wires between Chassis & Tailgate at Hinge Plane.

NOTE: the Aerial Diversity Module gets its power via Fuse F2 on your 2006 model, via Red/Green wire at X1143/6.
That Red/Green wire at socket #6 is slightly smaller than the Red/Black wire at 1143/1 (opposite end of connector)
that carries the "Radio ON" signal. See the Connector views showing Socket numbering on the connector.

I would FIRST look for a broken Red/Black wire in loom at hinge plane, if NO voltage at X1143/1 with Radio ON.
Please let us know what you find, as there are OTHER possibilities. Also, please let us know if you have INPA, as
that has a Screen for testing Antenna signal strength (without taking ANYTHING apart ;-)
George

[Dutchsea]

So it’s sorted. The black/red wire is indeed broken in the loom between the chassis and the tailgate. So I am very happy the I found the root cause.

I made a temporary connection between the broken wire and pin 1 on the diversity antenna amplifier and straight away the radio receives all stations again.

So the black/red wire indeed brings power to the part of the diversity antenna amplifier that amplifies signal of the radio fm/am antennas. (When the radio is turned on)

Next thing is to repair the wire permanently. Probably this weekend.

Thanks for the great advise and ISTA schedules.