2017 Polo GTI problems with DAB radio

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Djf94
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Drives: 2017 Polo GTI
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2017 Polo GTI problems with DAB radio

Post by Djf94 »

I've had my polo for coming up on 8 months now with no issues, all of a sudden in the last month I've started to lose signal on my DAB radio upon start-up. For the first 5 minutes when the engine is cold I get little or no signal on DAB stations, the radio will then override and find an FM station instead. I have had the car in at my local Volkswagen garage 7 times but with no results, have had a software update, new Aeriel base, new media unit and end less checks. Now I have been told that it may be due to weather however I checked with an employer who has the same car and they have no problems.
Wondering if anyone has the same problem or even better a solution??
Thanks, David
veteran
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Re: 2017 Polo GTI problems with DAB radio

Post by veteran »

I'm not sure whether DAB radio reception, as opposed to FM say, depends much on the receiver's power supply, but could it be that the battery in your Polo has got into a low-charge state and consequently the VW onboard battery management system (BBS) has decided to switch away from DAB to something else that possibly draws less power (as well as possibly also turning off other current-hungry devices)? It'd do that if it gauged that maximum reserve current was needed in order to operate stop/start. It just seems rather coincidental that your problem has started to occur during a particularly cold spell in Scotand, and therefore when the voltage of your battery will be at minimum. If the battery's gradually run down as well (reached a low state of charge) over some months, then that might trigger the BBS into doing something like that. I don't know if you make use of stop/start but, if you do, have you, by any chance, noticed that it's been turning itself off from time to time?

The first obvious thing to check out therefore is the battery. Measure the voltage across its terminals, both before and after you start the car on a cold morning. Put the battery on a suitable charger for at least half a day; that can't do any harm. That'll at least then rule out, or not as the case may be, the battery as the cause. (Incidentally, you should charge between chassis and the positive post, not between the positive post and negative post, as otherwise you'll bypass the battery 'sensor' (monitoring device) and the BBS will gradually lose track of how much charge is left in the battery).

I wouldn't put any faith in the VW workshop to sort it out.
joe6
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Re: 2017 Polo GTI problems with DAB radio

Post by joe6 »

The weather will have only a marginal effect - vey wet foliage for example can affect reception but since you are on the move will not be permanent so that explanation is just rubbish. The voltage seem a possibility as said above. Do other electrical devices cut out as well (eg aircon)? Not sure if the antenna base which you have changed contains the signal amplifier? If not then it is worth getting that checked out. There are different parts of the amplifier for the different frequencies FM and DAB and two output cables and connections. Could be an intermittent fault in either.
Djf94
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Re: 2017 Polo GTI problems with DAB radio

Post by Djf94 »

Appreciate both the replies. I don't use stop start much however have noticed it hasn't worked as much during the cold weather, I'm not the only one experiencing this though as my partners car has had the same problem with her stop start. The battery could well be worth investigating, the car is booked back in for Monday and I plan on this being the last time(most definitely won't be) will pass on the info on the battery and see what is said. Just want to make sure it's not a common problem and there is actually a fault before I keep chasing it up.
Only time it has worked in the past month is when the glove box was removed (to replace media unit) not sure if something else was removed that could be interfering, seems a coincidence if not
veteran
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Re: 2017 Polo GTI problems with DAB radio

Post by veteran »

Djf94,

I was about to make a second suggestion, concerning the cables associated with the aerial, but joe6 has beaten me to it. However, the following idea might help in tracking down the cause of the issue if it is indeed aerial-related.

I don't know exactly what the aerial on the 2017 GTI is like, and its cables too, but I did once retrofit a Bosch stub aerial on my old Golf. I think the GTI's aerial cabling will probably consist of a thin coax cable (carrying the signal to the radio, etc) and one, or possibly two, wires carrying the 12v feed to a tiny amplifier built into the base of the aerial. These two lengths of cables will each almost certainly be in two sections - a 'tail' sticking out from the aerial's base, and a long length going from there to the back of the entertainment system via the vehicle's B and A pillars on the nearside. The tail and the long length usually plug together, therefore, in the roof headliner gap. It could be that, although the VW workshop completely replaced the aerial itself, they may not have replaced that long stretch of signal/power cable. As joe6 has strongly hinted, you'd get the symptoms you're describing if there was a break in either the signal wire or in the 12v feed that comprise that long stretch (as well as the tail, but according to the workshop they've replaced the aerial); it'd be worth checking out all fuses associated with the aerial and its power feed, just in case one has blown or isn't fully pushed home.

If it's a wire break - for instance, the centre conductor of the coax - that break could be temporarily re-making as the temperature fluctuates; the wire being made of copper, it would readily expand and contract; the gap produced by the break could be just a tiny fraction of a millimetre and that'd be enough for the break to manifest itself and the signal become very small or lost altogether. The sensitivities of the DAB and FM inputs on the radio may be such that FM can still deal with a very weak signal as a result, but not so DAB, as a digital station will require a certain minimum signal level and if it doesn't get it, the reception will 'fall off the cliff edge'. If the entertainment unit was removed and replaced at some prior time, then the DAB/FM signal/power cable, which would run around the back of the glovebox and thence to the back of the radio, might have got trapped/damaged and a wire broken in this fashion, therefore.

BTW, when you originally set up your preferred DAB and FM stations in the infotainment display, did you remember to store each station? On my own more-basic Infotainment system (Polo 1.2 TSI Match Edition), I have to press a button at the side of the display for a minimum few seconds for that to happen. If you don't do that, the radio tends to randomly pick a waveband/station whenever you have the radio on.
Djf94
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Re: 2017 Polo GTI problems with DAB radio

Post by Djf94 »

Sorry for lack of updates, but 2 months since the original problem and still no fix. I have now been told Volkswagen Germany are now involved and tech reports are getting sent back and forth, not looking promising for a fix anytime soon
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