Hardwiring USB to Fuse Box

[Bunnyboileravoider]

Ladies & Gents,

I'm stuck, and would really appreciate help in identifying what I'm doing wrong. Hopefully this offers enough context.

Vehicle: 2006 2.0i facelift E85 (absolute entry level vehicle i.e. cloth seats, no extras, not even interior footwell lights (let alone USB ports)
Objective: 2 x independent USB ports, active only when ignition is on, but permanently fixed (for interior LED footwell lights)
Intention: tap inline using 3A fuse into one of the spares, or piggy back fuse with one of the existing 'ignition on' 5A fuses, connect that to voltage reducer with 2 x USB ports

Equipment:
- piggy back connector (https://www.halfords.com/tools/fuse...p_IO1LaPfoh3tQzAcqSqwy_yFakihc2UaArcrEALw_wcB),
- 12V to 5V/3A connector (https://www.amazon.co.uk/gp/product/B06XSCCLCD/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1)
- multiple fuses
- multimeter

Ideas already tried & discarded:
- use cigarette lighter socket? Always on, looks ghastly, ashtray cover always open etc. etc. Even if I hid it under the trim, it's still 'always on'.

- use USB port on stereo? Despite stereo being 'ignition only', it retains some power for clock etc. and testing revealed the USBs are always live. Even if they weren't, it would require rerouting cable through fascia, all holes I'd rather not create.


Story so far...

As these pictures show, I've opened it all up (thanks to the absolute HEROS in this forum who've been there and got the t-shirt many years ago and since)

identified the screw recommended by predecessors as a perfect chasis point,

changed that screw for a stainless steel one and added a washer for good measure, bared the black wire for Earth and screwed it in tight. I've crimped the red Live ends together tightly (it's not going anywhere), and felt very pleased with myself...

...except that it still doesn't work, neither with the ignition off, nor on. I've tried various 5A fuses (believe it or not there are fuses in the ports where I don't have those accessories, such as heated seats, parking sensors etc., so that really didn't help either). I've referred to the ste-by-step guide in this thread (https://z4-forum.com/forum/viewtopic.php?f=2&t=104224&hilit=iphone&start=15), and about 3 others (the fuse diagrams showing 'always on' and 'ignition only' were brilliant in theory, by the way, so thank you).

I'm just not sure what the hell else to try :headbang: :headbang: :headbang:

Thanks in advance for any help

 

[Zulu4]

I see that you've only got one fuse in your piggy back connector photo. Did you try putting both fuses in it when testing ? i.e. the fuse for the USB and the fuse for the circuit you're connecting to.

Also, did you double check that ground bolt really does connect to the rest of the chasis ?

 

[Bunnyboileravoider]

Thanks Zulu4 - yes, I had both fuses in when I was trying to piggy back, and then just the one when I tried the supposedly 'spare' slots.

 

[TheDan]

It sounds to me like your ground isn't properly grounded. When I did mine I actually ended up upside down in the footwell and used a different ground further inside.

I would grab a multimeter and work your way out from the source (working fuse location):

• Multimeter between fuse terminal and ground. If 12v move to next point:

• Plug in piggy back and multimeter between live wire and ground. If 12v move to next:

• Plug in 12v to 5v connector and multimeter between live and ground again. If 5v move to next:

• Attach USB and multimeter between USB and ground.

Hopefully that will identify the issue somewhere along the chain. If you've already tried all of that then I am sorry!

 

[Bunnyboileravoider]

Ok - that makes sense. I hadn't thought of doing all of that (despite realising it's a fault detection challenge), and frankly didn't know how to do all of the above.

This is great, TheDan, so thank you. It's dusk now and I fear if I try doing it in the dark, I'll give myself a different problem. Plus I just want to smash it all up with a hammer right now :rofl:

I'll update one way or another tomorrow morning. Seriously - thanks.

 

[Bunnyboileravoider]

Well...if you guys are anything like me (and I suspect many are), leaving it alone would have been the smart thing to do, but it was never gonna happen... :rofl:

@TheDan - you're a bloody legend, mate. Thank you. Followed your advice, used the cigarette lighter to give me voltage, tested the Earth point - nada. Then I played around and found the chassis was doing it's thing, but for some reason the screw wasn't. Didn't I feel a berk when I discovered it's sitting in a plastic retainer behind that black trim :x

I got a bit medieval - undid half a dozen phillips screws retaining the glovebox frame, found a chassis screw, tested using the multimeter as you suggested, found it worked and then tried the black cable itself. Bingo! Once again, thank you TheDan :ilz4f:

(And no - they won't be disco lights like the pic )

 

[TheDan]

You're very welcome. I too wouldn't have been able to leave it alone! I expect a disco ball to be plugged in to the USBs ok? :rofl:

Glad you got it sorted!

 

[inkey$]

Can you photograph the screw you used to earth it all? Im about to do the same for phone charge, and it would be great to get direction on something tried and tested. Was going to piggyback the horn or heated seats fuse (AUX - ignition point 1).

 

[Bunnyboileravoider]

inkey$ - I'm sorry, but after my euphoria last night, I couldn't bring myself to facing the carnage I'd created first thing the next morning, so it's all back in place.

But I can tell you exactly where it is if you refer to the 4th and 5th picture (of the fuse box), above. Those pictures show the duff one - others have used it successfully, but I think they were in the US, so I suggest you ignore it.

Instead, when you get to the point I was at i.e. glove box hanging vertically, fuse box fully exposed, I suggest you take a phillips screwdriver to the 6 retaining screws holding the black, shiny plastic frame against the main trim itself (including my previously anticipated screw). It will loosen to the point where it feels as though a couple of plastic trim tabs are all that's holding it in place, but it will stay there reducing your chaos (at least, mine did).

At that point though, it dropped enough to let me see a strip of chassis about 40cm wide (into which my duff screw had been fitted), but more importantly exposing 2 more screws that are metal-on-metal. I used the one about 5cm to the left of my original target.

Per my new sparky mentor, TheDan, I'd suggest testing it first before replacing all the frame screws etc., but for me it was absolutely perfect. The added bonus of course, is it's proximity to the fuse box - meaning you don't have miles of wires to tidy up. After that it was a simple case of running my cables where I wanted them.

As an extra tip in case it helps, there's a semi-circle cut out by the right hinge on the glove box. That meant I could run one of my USB female cables behind the glove box hinge (I had to pull quite forcefully against the trim to get it through the back), and then straight up into the vacant blank about 10cm forwards. In that way I've retained easy service access to the USB connection point, but not had to drill holes or have anything unsightly. Shout if you want a pic of where that is.

 

[inkey$]

inkey$ - I'm sorry, but after my euphoria last night, I couldn't bring myself to facing the carnage I'd created first thing the next morning, so it's all back in place.

But I can tell you exactly where it is if you refer to the 4th and 5th picture (of the fuse box), above. Those pictures show the duff one - others have used it successfully, but I think they were in the US, so I suggest you ignore it.

Instead, when you get to the point I was at i.e. glove box hanging vertically, fuse box fully exposed, I suggest you take a phillips screwdriver to the 6 retaining screws holding the black, shiny plastic frame against the main trim itself (including my previously anticipated screw). It will loosen to the point where it feels as though a couple of plastic trim tabs are all that's holding it in place, but it will stay there reducing your chaos (at least, mine did).

At that point though, it dropped enough to let me see a strip of chassis about 40cm wide (into which my duff screw had been fitted), but more importantly exposing 2 more screws that are metal-on-metal. I used the one about 5cm to the left of my original target.

Per my new sparky mentor, TheDan, I'd suggest testing it first before replacing all the frame screws etc., but for me it was absolutely perfect. The added bonus of course, is it's proximity to the fuse box - meaning you don't have miles of wires to tidy up. After that it was a simple case of running my cables where I wanted them.

As an extra tip in case it helps, there's a semi-circle cut out by the right hinge on the glove box. That meant I could run one of my USB female cables behind the glove box hinge (I had to pull quite forcefully against the trim to get it through the back), and then straight up into the vacant blank about 10cm forwards. In that way I've retained easy service access to the USB connection point, but not had to drill holes or have anything unsightly. Shout if you want a pic of where that is.

Thanks for all of this. I'll let you know how I get on!