Wiring in a new switched 12v circuit - what about neutral?

Gazzaman28

New Member
Hi all,

I've got a dashcam and a DAB radio (Pure Highway) both running from a cigarette lighter extension lead, and despite my best efforts in trying to remember to unplug it every time I switch off the car, I managed to forget recently and the battery went flat! So I then decided I needed to wire in a new switched 12v circuit. I've got all the bits, a fuse piggy back cable, some 12v cable, wire strippers/crimping tool, bullet connectors, etc. I've checked with a multimeter to ensure the piggy back fuse is connected to a circuit that's only live when the ignition is on, but I feel like I'm missing something really obvious - the piggy back cable only has a live connector, so other than sticking the neutral to somewhere on the car body (which isn't really practical), where can I tap into in the dashboard (I don't mind which side but it would be neater if it was near the glovebox) to connect up the neutral side of my circuit in a neat and tidy way?

Thanks in advance for your help.
 
Hi all,

I've got a dashcam and a DAB radio (Pure Highway) both running from a cigarette lighter extension lead, and despite my best efforts in trying to remember to unplug it every time I switch off the car, I managed to forget recently and the battery went flat! So I then decided I needed to wire in a new switched 12v circuit. I've got all the bits, a fuse piggy back cable, some 12v cable, wire strippers/crimping tool, bullet connectors, etc. I've checked with a multimeter to ensure the piggy back fuse is connected to a circuit that's only live when the ignition is on, but I feel like I'm missing something really obvious - the piggy back cable only has a live connector, so other than sticking the neutral to somewhere on the car body (which isn't really practical), where can I tap into in the dashboard (I don't mind which side but it would be neater if it was near the glovebox) to connect up the neutral side of my circuit in a neat and tidy way?

Thanks in advance for your help.
Near glovebox, take no prisoners and ring terminal (6mm) on the major earthing point at the base of the A-pillar, nice and simple.

image.jpeg


Must be lots be other options to piggy back near the glovebox, indeed glovebox light, climate hardware behind glovebox, radio & climate unit next door, no idea of cable sizes/amps/wattage you would have to investigate and do your sums, depending on what your kit is drawing, all a bit above my pay grade.

Andy
 
Near glovebox, take no prisoners and ring terminal (6mm) on the major earthing point at the base of the A-pillar, nice and simple.

View attachment 67976

Must be lots be other options to piggy back near the glovebox, indeed glovebox light, climate hardware behind glovebox, radio & climate unit next door, no idea of cable sizes/amps/wattage you would have to investigate and do your sums, depending on what your kit is drawing, all a bit above my pay grade.

Andy

Thanks Andy. I was playing around with fuses for various circuits to see what would work best and it looks like my glovebox light doesn't actually work at all (it shares a fuse with the number plate light and that light does work so it's definitely not a blown fuse) so I'll have to have a play with that light. Hopefully it's just a bulb, if so then i'm sure it won't be too hard to chop the neutral cable off that circuit and join on my neutral circuit to it as well.
 
Thanks Andy. I was playing around with fuses for various circuits to see what would work best and it looks like my glovebox light doesn't actually work at all (it shares a fuse with the number plate light and that light does work so it's definitely not a blown fuse) so I'll have to have a play with that light. Hopefully it's just a bulb, if so then i'm sure it won't be too hard to chop the neutral cable off that circuit and join on my neutral circuit to it as well.
The glovebox light often does not work due to poor/weak design of the switch that is inevitably broken. This switch completes the circuit when the glovebox is opened but being broken the glovebox light burns continuously and quickly uses up its lifespan, check the bulb. Remove glovebox to confirm breakage but no big deal, Paul(@depronman) prints a low cost tang to fix, no doubt he will be along soon.

Andy
 
The glovebox light often does not work due to poor/weak design of the switch that is inevitably broken. This switch completes the circuit when the glovebox is opened but being broken the glovebox light burns continuously and quickly uses up its lifespan, check the bulb. Remove glovebox to confirm breakage but no big deal, Paul(@depronman) prints a low cost tang to fix, no doubt he will be along soon.

Andy

Thanks Andrew, I've found https://www.a2oc.net/community/index.php?threads/general-a2-servicing-information.23606/#post-187937 so I'll remove the glovebox and have a play around with the cabling and mechanism. Getting the light working again isn't a top priority, I didn't realise it had a light until last night, but it'll be good to see if I can fix it anyway.
 
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