Glovebox fuses

I feel as if I ought to apologise before even asking this question, because you could quite rightly say, 'Why don't you get outside with a multitester and work it out for yourself, you lazy git?'

And if you are inclined to say that, then I'll take it squarely on the chin.

So I apologise in advance.

The question, if you feel able to lower yourselves to help such a feckless oik, is this:

Are there any fuses in the glovebox which become live only when the engine has started?

I don't mean ignition-switched fuses in the traditional sense, i.e. those which become live when the key is turned to the first position. The car is a 2017 2.0TFSI, FWIW.

Thanks

Pete
 

jrumball

Registered User
Lazy......

See this thread for installing an Audi UTR dashcam

https://www.audi-sport.net/xf/threads/how-to-install-an-audi-utr-dashcam.378844/#post-3351011

If that's too much effort

Top half of fuse box is Permanent Live, Bottom half is switched , Fuses circled are good to tap for a low draw device , F40 is the lighter socket and by moving the fuse you can change wether it is live the whole time or only when the ignition is on ......

Fuse Box copy.jpg
 
Lazy......
On this occasion, yes. Don't say I didn't fess up in advance.

If that's too much effort
Nothing is too much effort, old fruit. Nothing.

I know about the positioning of F40. However, in its ignition-switched position, it's live when the key is turned to the first detent.

I'm asking to see if there's a fuse which only becomes live with the engine running, i.e. no power at key position 1.

I suspect that F40 has its power temporarily cut by the electronics while the starter motor is engaged, i.e. key position 2, and that it isn't the only one.

Incidentally, I think your how-to write-ups are a work of genius, no matter how idle and lardy-ars*d you think I am.

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Top half of fuse box is Permanent Live, Bottom half is switched
Sorry, I should have put two and two together at this point...

I guess it's reasonable to infer, then, that all the fuses in the bottom half (the switched ones) will most likely have their power cut (or significantly reduced) momentarily when the starter is turning the engine over.

If that is the case then there is no such animal as the fuse I'm looking for and I'll have to tackle this from a different angle.

I apologise most 'umbly for wasting anyone's time, especially Mr Rumball :couple inlove:

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The switched fuses do not have their power cut during starting.
If there's no interruption - or reduction - of power during cranking, why would a dash camera correctly hardwired to fuse F40 (in the switched position) turn itself off when the starter is operated?

It turns on and begins recording at ignition switch position 1 (as you'd expect) , but then turns off at position 2 when the starter engages. Then it won't power up again without removing and reinserting the connector. That's obviously no use.

I'm not arguing with you, not in the slightest - I'm just trying to get to the bottom of why it's doing this.

If I transfer the camera to our other car (which has an identical hardwire set-up except that it's tapped to a fuse which is live only when the engine is running, it works faultlessly.

Given that the camera itself seems to be working properly (it's been back to Roadhawk for testing), the only reason I can think of for it doing this is that the power to fuse F40 is either momentarily suspended, triggering the shutdown, or drops below the camera's supply threshold, with the same result.

Whichever it is, it's a pain in the posterior.

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ZipZap01

Registered User
I've had same issue with dashcams (connected to f34 or 35).

From recollection, my 12v socket accessories (f40) don't cut out during start.

During engine start, the battery voltage drops below the camera threshold and it shuts down.

On a cold day, you could turn the key straight to start and the cam would work, but shut down as soon as the engine tried to restart after a stop-start event.
 
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I've had same issue with dashcams.

During engine start, the battery voltage drops below the camera threshold and it shuts down.

On a cold day, you could turn the key straight to start and the cam would work, but shut down as soon as the engine tried to restart after a stop-start event.
So did you resolve it or just live with it?

Sod's law says that the one time you need the camera to do its thing, it hasn't even had the decency to turn itself on.

You can see the appeal of having a fused supply which is only live when the engine is running because then none of this nonsense happens, but it seems we don't have one of those.

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AlS3BE

Registered User
Permanent live or switch live shouldn’t be interrupted when cranking generally. Interruptions while cranking can point to a low charge in the battery. Old batteries or faulty batteries can cause this. I suppose it could be a faulty starter taking too much current as well.
Had a similar problem in another car when stop start kicked in the headlights would turn off while cranking and stay on once running. New battery sorted this.
 

ZipZap01

Registered User
So did you resolve it or just live with it?

Sod's law says that the one time you need the camera to do its thing, it hasn't even had the decency to turn itself on.

You can see the appeal of having a fused supply which is only live when the engine is running because then none of this nonsense happens, but it seems we don't have one of those.

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Changed the camera for a modern one which handles power drop-outs correctly. The issue was I had originally used a very old (2011) dashcam which was on its last legs, and wasn't designed with start-stop in mind; and I had changed it for a cheap go-pro clone rather than a proper dash cam. This couldn't cope with the power supply cutting out while the starter motor ran, and would turn on/off every time the starter engaged. In this case, I'd just bought a dash cam hard wire kit, and connected it to the camera via USB. The camera was designed to switch on and off with USB power - but it couldn't cope with short (1-2 seconds) power drop outs, which made it very confused.

On the modern one, the camera has a built in capacitor which keeps the camera powered for 5 seconds. If the power drops out for less than that (e.g. during a start), then the camera just keeps doing exactly what it was doing before.

I don't see how having a live only when the engine is actually running would help. You would still get short power drops when start-stop kicks in, or is about to kick in, and you cancel it before the engine fully stops. These would still confuse the camera. Even if it doesn't and the camera powers down, it would then have to go through it's boot up sequence every time the engine restarted, so you'd miss loads of footage (especially in high risk areas like junctions).

I suppose it could be a weak battery and the battery dropping excessively during start, but these cars are very sensitive to battery problems and alert if the battery is discharged or weak. However, they can hide early degradation by turning things off electronically, so this might not be obvious if the battery is only slightly weak.

In all honesty, it sounds more like your dash cam/hard wire kit are faulty.
 
Changed the camera for a modern one which handles power drop-outs correctly. The issue was I had originally used a very old (2011) dashcam which was on its last legs, and wasn't designed with start-stop in mind; and I had changed it for a cheap go-pro clone rather than a proper dash cam. This couldn't cope with the power supply cutting out while the starter motor ran, and would turn on/off every time the starter engaged. In this case, I'd just bought a dash cam hard wire kit, and connected it to the camera via USB. The camera was designed to switch on and off with USB power - but it couldn't cope with short (1-2 seconds) power drop outs, which made it very confused.

On the modern one, the camera has a built in capacitor which keeps the camera powered for 5 seconds. If the power drops out for less than that (e.g. during a start), then the camera just keeps doing exactly what it was doing before.

I don't see how having a live only when the engine is actually running would help. You would still get short power drops when start-stop kicks in, or is about to kick in, and you cancel it before the engine fully stops. These would still confuse the camera. Even if it doesn't and the camera powers down, it would then have to go through it's boot up sequence every time the engine restarted, so you'd miss loads of footage (especially in high risk areas like junctions).

I suppose it could be a weak battery and the battery dropping excessively during start, but these cars are very sensitive to battery problems and alert if the battery is discharged or weak. However, they can hide early degradation by turning things off electronically, so this might not be obvious if the battery is only slightly weak.

In all honesty, it sounds more like your dash cam/hard wire kit are faulty.
Thanks. I'm getting the battery properly tested in a week or so.

For what it's worth, I do know it isn't either the camera or the hard wire, but we'll see what comes out in the wash. All I can do is eliminate things one at a time.

Stop/start isn't a factor here. I don't use it.

Out of curiosity, do you know at what voltage the low battery warning is triggered?

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