No Power to cigarette lighter... where to start?

[HoTWire]

Car electrics are wizardly art to me so I'll need some step by step help.

I have a cigarette lighter, I need it to charge my phone so I can use my phone as a speedo. Only problem is it doesn't work. The single cable in the back hasn't been fiddled with apparently, when the engine swap was done.

I've got a multi meter, no idea what I'm doing and two weeks to fix it. Hit me with your best step by step instructions.



Will also accept alternative ways to power the phone or laptop.

[goldnrust]

Ok, lets this is my best attempt at step by step (apologies if too patronising!)...

Set the multimeter to measure voltage at an appropriate voltage range. Check the voltage across the terminals of your battery to make sure the multi meter is set up correctly and reading as you'd expect it to.

Now we know the meter is correctly measuring voltage, use it to make sure that you're not getting 12v to the cigarette lighter. The positive will be in the back/base of the lighter, and the negative/earth the tubular section. I've had a number of cigarette lighters that have power going to them, but are too corroded transfer that power to a phone charger or whatever.

Presuming you haven't got 12v across the 2 contacts in the cigarette lighter, then there's 2 potential failures, either 12v is not being fed to the lighter, or it's not getting a good earth connection back to the battery to complete the circuit.

Test the earth first. Set the multi meter to continuity tester mode, this normally is near the resistance settings and has a speaker symbol. Test this mode by touching the two electrodes together, the meter will make a sound to tell you that you have a continuous circuit. Next up find a good earth point elsewhere in the cabin, and place one of the electrodes on it, check the other against the earth contact on your cigarette lighter (the inside tubular section). If the meter makes a buzz then you know its got a good earth, and therefore the problem likely lies in the 12v supply. If the meter wont buzz then you've likely found an earthing problem.

The second half of the same test is to put the meter back to the original voltage measuring mode, and so you check the 12v connection to the cigarette lighter. Now check the 12v connect in the bad of the lighter against your known good earth point. If the meter reads 12v then that suggests that power is getting to the lighter and the problem is an earthing problem. If you've not got 12v then it suggests it's a power supply issue

Hopefully the two halts of the above test match up, both suggesting the same problem! Let us know your findings and we'll go from there.

[820]

Have you checked the fuse?

[baggabones]

What they both said ^^ or for a simple fix ...a new live feed from a suitable terminal on the fuse box and a new earth wire to a common earthing point under the dash somewhere

[ChasR]

You could put in a new live feed and bypass the problem but as someone who has bought his share of bodged cars it would be nice to see if it was a simple fix in the first place .

[93fxdl]

A way of making things a bit easier, get an accessory lighter plug, wire a 12v buzzer to it and plug in, then you have both hands free fiddle with connections and you don't need to keep looking at a meter
Ttfn Glenn

[colnerov]

Hi, As a further complication some cars have a live battery feed and some have ignition feed so be aware, so do this testing with ignition both on and off.

Colin

[taurus]

Great advice above, but if all else fails or you don't want to mess about with the original wiring, you could always fit a motorcycle 12v accessory socket.

www.ebay.co.uk/itm/Motorcycle-12V-USB-Waterproof-Cigarette-Lighter-Power-Port-Outlet-Socket-Useful-/301497398663?pt=LH_DefaultDomain_3&hash=item4632a53587

Pretty much a foolproof way of adding 12v accessory socket and USB charging point.

[bortaf]

First place i'd look is the earth, there should be 2 wires at the rear, live and earth ? otherwise as above (all good advice there )

[HoTWire]

Thanks folks, I'm back in civilisation tomorrow, so I'll have a go at lunch time and get back to you. May do one of those 12v bike things anyway as it is mainly needed for usb

[Deleted]

Jun 28, 2015 7:34:46 GMT HoTWire said:

Car electrics are wizardly art to me so I'll need some step by step help.

I have a cigarette lighter, I need it to charge my phone so I can use my phone as a speedo. Only problem is it doesn't work. The single cable in the back hasn't been fiddled with apparently, when the engine swap was done.

.

And there is you problem, you need two wires one an earth and one is the live feed so look for a stray wire that has come loose.

[taurus]

Depends if the single cable is twin core - if it is then the fed & earth will be in the one cable.

[colnerov]

Hi,If the socket is in a metal dash panel it may not need a separate earth.

I wonder if the OP is confused enough yet?

Colin

[eg2]

Silly question but did you check the fuse?

[HoTWire]

Apologies for no update with this, I went to follow the instructions on Saturday afternoon and found that my multimeter had decided to stop working (possibly battery), because this is the sort of thing that happens. Will attempt to get it sorted mid week.

[hkr91]

Some of the cigarette lighters have earth connected via the cigarette lighter socket body and hence only need one live wire.

What car is the socket in?

[DarrenW]

Quite literally a HoTWire problem.

Sorry

[jamesd1972]

First double check there are no stray bits of metal in there that caused the problem - its really common for bits of accessories / screws etc. to short ciggy lighters out.
I'd be surprised if its not the fuse but finding these can be a PITA. I've come across cars with two fuse boards and still a separate one for the lighter !
James

[barty]

the ciggy lighter sometimes shares a fuse with another item ie the horn or something like that ( the handbook will say) or it should say on the fuse box lid.
Before you mess around too much , have you tried an accesory in the socket like a sat nav or phone charger ?