DAB Aerial - Open Circuit

[Watson306]

Hi All,
I've just purchased an A4 B8.5 3.0tdi Avant Black Edition.
It's fully loaded and I'm loving it.
It has a few bodywork niggles that I'm going to work my way through and 2 faults.
One of which is a parking sensor which I'm on top of.
The other is this:

Fault Found:
02877 - Digital Radio Antenna (R183)
011 - Open Circuit
Freeze Frame:
Fault Status: 01101011
Fault Priority: 7
Fault Frequency: 1
Reset counter: 153
Mileage: 121626 km
Time Indication: 0
Date: 2019.10.20
Time: 15:08:59

It doesn't pick up any DAB stations, and initially I thought it was just a signal issue but after I had it scanned obviously I'm thinking I can get to the bottom of this.
Any ideas what maybe causing this?

Thanks in advance

 

[JohnS3]

If you clear the fault does it come back?
Check the connections on the radio module and the DAB antenna on the right hand D pillar

 

[Watson306]

I have cleared the error and it does come back.
Also no dab channels are picked up on searching.
I'll take a look at those connections.
Are they on the rear quarter window on the drivers side?

Many Thanks

If you clear the fault does it come back?
Check the connections on the radio module and the DAB antenna on the right hand D pillar

 

[rum4mo]

I'd try the end of this cable at the front end first, you need to remove the C pillar trim to get to the rear end of that cable .

 

[Watson306]

Thanks for your input.
Can anyone point me in the direction of any guides to access the end behind the head unit?
Also the other end - am I right in thinking it attaches to the os rear side window in the boot?

Many Thanks

I'd try the end of this cable at the front end first, you need to remove the C pillar trim to get to the rear end of that cable .

 

[JohnS3]

The DAB receiver is in the left hand side of the boot. The DAB antenna amplifier is mounted on the right hand D pillar

Just for your reference the am/fm radio uses 2 amplifiers. One on the left C pillar and a second unit mounted at the top of the rear screen.

If you have a factory TV tuner fitted, this uses 3 amplifiers, different modules on the C pillar and rear screen with additional outputs and a third amplifier on the right hand C pillar.

This information is for the facelift Avant, the pre facelift uses a different antenna system.

Hope this helps.

 

[Watson306]

Thanks JohnS3
I have only just got round to checking this - I have checked the cabling to what I believe is the DAB receiver (with PN 4G0 035 061 E ).
And the cabling is all secure. I even removed the aerial cabling and this stopped the FM radio receiving.
How do I get to the Antenna Amp on the D pillar? Is it easily accessible?
Is there then a connection to the aerial I can check?

The DAB receiver is in the left hand side of the boot. The DAB antenna amplifier is mounted on the right hand D pillar

Just for your reference the am/fm radio uses 2 amplifiers. One on the left C pillar and a second unit mounted at the top of the rear screen.

If you have a factory TV tuner fitted, this uses 3 amplifiers, different modules on the C pillar and rear screen with additional outputs and a third amplifier on the right hand C pillar.

This information is for the facelift Avant, the pre facelift uses a different antenna system.

Hope this helps.

 

[JohnS3]

You can get the trim off. Involves taking the boot side panel off so you can remove the d pillar trim.

Does your radio unit have 3 antenna wires? 2 will be in a double fakra plug (AM/FM) and a single fakra towards the middle of the unit which is the DAB antenna.

 

[Watson306]

I'll take a look in a bit at the trim, but I did take a pic of the unit the other day.
See attached.

You can get the trim off. Involves taking the boot side panel off so you can remove the d pillar trim.

Does your radio unit have 3 antenna wires? 2 will be in a double fakra plug (AM/FM) and a single fakra towards the middle of the unit which is the DAB antenna.

 

[JohnS3]

Attachment?? Can’t see any images.

 

[Watson306]

Apologies - here we are.

 

[rum4mo]

Did you check that the single Fakra connector below the twin Fakra was fully plugged in?

 

[Watson306]

Yes, I unplugged and plugged back in with no change.
I can't seem to find the amplifier, but I have to admit I've not seen one previously.

Did you check that the single Fakra connector below the twin Fakra was fully plugged in?

 

[rum4mo]

The amplifier is in the rear of the car, ie behind the trim in the C or D pillar, what did you find when you removed the trim panel from inside the car?

 

[JohnS3]

It looks a bit like this

 

[rum4mo]

So, as you can see, at the front end there is the SMB female coax connecter with a Fakr plastic retainer to keep the lead connected at all times, this is the power supply input and signal output, and at the rear end the input which is the aerial in the window.

 

[JohnS3]

When you get the interior trim off might be worth running a continuity test on the cable between the amplifier and the radio module.

 

[rum4mo]

Maybe sounds a bit wasteful, but if you are not someone that is happy with checking continuity, why not buy a cheap "screen mounting" DAB aerial from Halfords, and plug that into the back of the receiver, if you are in a reasonable DAB signal area if you then loop the aerial over the headrest you will get DAB reception without needing to connect in the +12V and 0V - that was what I did when retro fitting a DAB radio to a non DAB S4, really just to confirm that the used radio I bought was working and could get its CP sorted out.

If you did that then you would know that it was really some where along the aerial external path that the problem was, though if it was me, I'd get in there under the trim to make sure every thing was looking okay.

 

[Watson306]

Hi All,
I've just got the chance this evening to remove the trim again and the pic above helped no end as I found that the aerial plug was in fully on the amplifier.
I removed and then pushed in completely and I now have dab signal.
I guess I may need to tape it in if it comes out again but as I don't know how long it's been an issue I'll have to keep an eye on it.
Thanks everyone for there efforts and advice it really is much appreciated.
I have another question regarding the rear bumper diffuser but I'll create a new post.

Once again Thank you all so much.

 

[JohnS3]

Glad it’s sorted out. The fakra plugs should have a clip to stop them working loose. A bit of tape will certainly help if the clip has been damaged.

 

[rum4mo]

Yes that is the only purpose of that Fakra system, it is just a plastic retainer cage that converts the usual SMB co-axial to a standard that should stay connected under all conditions.

What I've found accidentally by experience is, when someone strips cars down for recycling, they seem to pick one of two ways when it comes to these VW Group aerials, option (1) - chop the leads before the connectors, this way is good as it protects the connectors from damage. option (2) - brutally get the Fakra lead and the I/P leads off, that way tends to end up with a working aerial amplifier without its complete Fakra matching and so latching plastic part. I know this I bought one of them, though it did make retrofitting a new 3rd party DAB lead in a lot easier, lead end Fakra removed SMB F-M elbow fitted, perfect job, hopefully some tape was then added, I've forgotten!

 

[JohnS3]

Agreed, unless handled badly the plugs should not work loose. When I fitted my TV tuner I bought a crimp tool and made my own cables with connectors from Co-Star. Cheaper than you might have thought too and their crimp tool can be bought elsewhere for far less.

https://www.co-star.co.uk/products/fakra-connectors/

 

[rum4mo]

Just as well that I did not bump into that website or I might have swopped the inline connector for an elbow one - and have an extra crimping tool to add to my collection, I don't mind buying tools, as the B8 saloon installation is neater if an elbow connector is used.

I think that I've got a set of tools for making up satellite leads as I wired all the downstairs rooms for 2 satellite+TV+FM years ago, even located, fixed and aligned the dish, better doing some of these things yourself as our house has no visible satellite cabling on the outside, we are in a hollow near our local fill-in mast so terrestrial TV was not good even when piped in from a local development mast. Similarly a box of tools for VW Group wiring, all good stuff!

Edit:- I've saved that website - just in case, ta!

 

[JohnS3]

I use RG174 cable! (just in case)