Rewiring passenger 12V socket to ignition

Hi there, I recently got gifted one of those replacement sockets to convert the cigarette lighter into a double USB port. I'm fairly sure it's this one: https://www.amazon.com/gp/product/B076D8CQYV/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1


Stupidly easy install on the driver's side, but that would leave me with 2-USB socket wired to the ignition (driver), and a 12V socket (passenger) which is constantly on. The only reason this is a problem is because my FM transmitter (and seemingly every FM transmitter ever produced) plugs into a regular socket and not a USB. I don't want to have to yank my FM transmitter out every time I turn the car off, and I don't want to have the transmitter or the new USB socket on always on, draining the battery or burning the car to the ground while I'm asleep.



I'm fairly inexperienced w/r/t electrical work, but it seems like it should only be a matter of swapping the source for the passenger socket from the battery to the ignition like the driver's side, so I could install the USB socket on the passenger side and have it turn off with the ignition as well. Trouble is I've got no idea how to go about achieving that, and I can't find anyone who's done the swap online. Any help or advice is much appreciated!

Given the way the 2 sockets are fitted in an XJ, swapping them over is not as simple as it would be on almost anything else (in fact, I'm quite impressed you've managed what you have).

Now I'm no sparks but pretty sure that a USB port with nothing plugged into it is not going to draw any current, so there's no reason why you couldn't just swap the +ive wires over between the 2 sockets.

Alternatively, as the USB ports are only 5v (& 6a max), you could disconnect the original power socket +ive (iirc, it has its own fuse, so you could simply pull that to make it safe) & run a wire from the lighter socket over to it.

XJI6191 said:

Now I'm no sparks but pretty sure that a USB port with nothing plugged into it is not going to draw any current, so there's no reason why you couldn't just swap the +ive wires over between the 2 sockets.

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From what I understand, it wouldn’t be the USB ports per se that would draw continuous power, but the blue LED(s) inside which light up when powered. Looking at the thing, it doesn’t seem to be feasible just to crack it open and remove the LED without destroying it, and i’ve had a very difficult time trying to find one that doesn’t have any kind of little light indicator.

As far as running a wire over to the non-ignition socket, is that just a matter of splicing in the same gauge of wire to make forks in both driver’s side wires and connecting the forked off ends to the new socket? Sorry if this is a doofus question, but the extent of my electrical work on the car has been reconnecting a split wire in the door boot lol

I woudn't worry too much about the draw of that blue LED. I would bet it draws less than the computer does when the vehicle is off.

This is my install: https://www.naxja.org/forum/showthread.php?t=1143807

I too did not care for the blue LED always being on. The biggest issue for me was how conspicuous it looked at night. I would pull the fuse for that socket when I didn't need it to be live. But I got tired of that, and at some point in the last year that LED burned out (whodathunk an LED would eventually die?) and it is no longer an issue.

If you are really concerned you could test the draw of the LED with a DVM. It is probably going to be ridiculously low. Running it on an automobile 12V battery I would expect the battery to die of old age long before the LED drained it.

Anak said:

I too did not care for the blue LED always being on. The biggest issue for me was how conspicuous it looked at night. I would pull the fuse for that socket when I didn't need it to be live. But I got tired of that, and at some point in the last year that LED burned out (whodathunk an LED would eventually die?) and it is no longer an issue.

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The one I've got comes with a little rubber stopper to cover it when not in use, so the light itself wouldn't be too much of an issue. The problem I'm trying to avoid is having something like a GPS or other USB powered device in there permanently later on, which I would just end up having to unplug when I turned the car off anyway, instead of having it go on and off with the car itself.

Anak said:

I woudn't worry too much about the draw of that blue LED. I would bet it draws less than the computer does when the vehicle is off. :thumbup:

This is my install: https://www.naxja.org/forum/showthread.php?t=1143807

I too did not care for the blue LED always being on. The biggest issue for me was how conspicuous it looked at night. I would pull the fuse for that socket when I didn't need it to be live. But I got tired of that, and at some point in the last year that LED burned out (whodathunk an LED would eventually die?) and it is no longer an issue.

I'd never leave anything plugged into any of those sockets (too tempting for the lightfingered brigade) - my issue is driving at night when those LED's seem very bright & a serious distraction (but you can turn an adaptor round in the socket).

If you are really concerned you could test the draw of the LED with a DVM. It is probably going to be ridiculously low. Running it on an automobile 12V battery I would expect the battery to die of old age long before the LED drained it.

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:thumbup:

As for wiring, it's a simple daisy chain job, just splice a wire into the ignition supply to lighter & connect the other end to where you removed the permanently hot wire from the power socket. How you make those connections is a matter of personal preference/skill level/what you've got lying around.

XJI6191 said:

As for wiring, it's a simple daisy chain job, just splice a wire into the ignition supply to lighter & connect the other end to where you removed the permanently hot wire from the power socket. How you make those connections is a matter of personal preference/skill level/what you've got lying around.

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Used all my artistic skills to draw up this before/after: https://ibb.co/2qWqGKz


Assuming that looks correct, I have two questions:

1. What should I do to the leftover wires running from the battery?

2. Can I splice the new wires in anywhere down the length of the ignition wires, or should they connect in wherever the ignition wires conclude? In other words, is "T" shaped fine, or does it need to be "V" shaped?

Yup, you've got it - but I'd leave the grounds as is.

It doesn't really matter where you make the splice, but I'd try to run the wire between the +ive terminals on each socket (long time since I had that switch panel out so having difficulty visualising what we're actually dealing with)

Just check that I was right about them being separately fused, in which case you can just pull the fuse for the OEM power socket & tie/tuck the wire up out of the way, otherwise you'll have to make sure there's no bare wire showing first.

XJI6191 said:

Just check that I was right about them being separately fused, in which case you can just pull the fuse for the OEM power socket & tie/tuck the wire up out of the way, otherwise you'll have to make sure there's no bare wire showing first.

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Yep, separate fuses, according to the diagram (https://knigaproavto.ru/shemy/en/jeep/cherokee/900-1997-2001-jeep-cherokee-xj-fuse-box-diagram.html) and my own test. I just pulled #1 on the diagram there. Thankfully, both 12V sockets are connected with plastic components on the end, so the live wire from the battery wouldn't be exposed anyway.


Specificity for the sake of anyone in the future: I spliced into the positive ignition wire, insulated it (https://www.youtube.com/watch?v=D4b_gSciGIg), and then hooked both that and the negative wire from the initial passenger connection into the spade connectors the USB socket came with. Then it was just a matter of filing away some of the old material so the new socket would fit and then plugging everything in.



It turned out looking great, and comes on and off with the car. Thanks a million!!!!

Great result - for me too: after all these years finally managed to post something useful.

DonQuiXJote said:

Specificity for the sake of anyone in the future: I spliced into the positive ignition wire, insulated it (https://www.youtube.com/watch?v=D4b_gSciGIg)

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There are easier/faster/safer ways to do it! https://www.delcity.net/store/Quick-Splice-&-Tap-Connectors/p_901562

XJI6191 said:

:thumbup:

As for wiring, it's a simple daisy chain job, just splice a wire into the ignition supply to lighter & connect the other end to where you removed the permanently hot wire from the power socket. How you make those connections is a matter of personal preference/skill level/what you've got lying around.

Click to expand...

Before simply connecting a 12v socket to just any hot wire, remember the cigarette lighter socket is designed for 20 or more amps, the switch is not, the normal wiring is not. If you want a switched 12v socket, use a relay on the 12v and a large gauge wire from the relay to the battery, otherwise, hook it with a large gauge wire directly to the battery. I use 10ga.

old_man said:

Before simply connecting a 12v socket to just any hot wire, remember the cigarette lighter socket is designed for 20 or more amps, the switch is not, the normal wiring is not. If you want a switched 12v socket, use a relay on the 12v and a large gauge wire from the relay to the battery, otherwise, hook it with a large gauge wire directly to the battery. I use 10ga.

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So is how I hooked it up going to cause problems or is what you explained just a better way of going about it? If it is an issue the way I've got it, could you go into more detail on how to rectify it from what I have now?

Sorry Old Man, you've lost me - & confused OP. A relay for 2 x 5v USB ports - really?

It's because the lighter has that rating AND is ignition controlled that there is no problem tapping in the much lower draw for the other socket. It may well take 20a to heat up the lighter element but not to run any/everything that might be plugged into both sockets.

RCP Phx said:

There are easier/faster/safer ways to do it! https://www.delcity.net/store/Quick-Splice-&-Tap-Connectors/p_901562

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Easier & faster? yup! But safer? no way: indeed, considered opinion is they are best not used at all (but can be forgiven in an emergency get-you-home situation.)

XJI6191 said:

Sorry Old Man, you've lost me - & confused OP. A relay for 2 x 5v USB ports - really?

It's because the lighter has that rating AND is ignition controlled that there is no problem tapping in the much lower draw for the other socket. It may well take 20a to heat up the lighter element but not to run any/everything that might be plugged into both sockets.

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If all you ever want to plug into that 12v port is a usb charger, then fine. Just remember, somebody will want to plug in something that pulls a lot more current sometime. If they do, you can easily burn up wires or blow fuses. For instance many jump start boxes can plug into the cigarette lighter socket to charge your main battery. Presto, burned up wires. Many older non LED hand held spotlights pull 20 or more amps. I recommend replacing the cigarette lighter socket with a dedicated dual USB charger outlet and be done with it.

Wouldn't argue with any of that but my suggestion was based on OP's quite specific requirements. As I recall he had replaced the power socket with a twin USB outlet but wanted it to be ignition controlled. I figured that even if the lighter socket was running at 20a there would be no risk (even to Jeep's infamous marginal wiring) in adding, say, a phone charger & GPS.

Coincidentally, I bought a new starter pack a couple of weeks ago, that has an alternative lighter socket plug (which I'd not seen before) - but I'd never use it, for no other reason than just doesn't seem right, so wouldn't feel comfortable with it.

XJI6191 said:

Wouldn't argue with any of that but my suggestion was based on OP's quite specific requirements. As I recall he had replaced the power socket with a twin USB outlet but wanted it to be ignition controlled. I figured that even if the lighter socket was running at 20a there would be no risk (even to Jeep's infamous marginal wiring) in adding, say, a phone charger & GPS.

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Yeah exactly, I wanted to avoid having my FM transmitter always on or having to unplug it every time I park the car. Swapping the twin USBs for the 12V as is would have caused the same problem, but I wouldn't be able to unplug it.



So from what I understand, my FM transmitter plugged into the cig lighter plus the phone charging cables in the 2 USB ports are fine, I should just avoid plugging into the cig lighter anything like a vacuum or lamp that would pull excessive amperage?

XJI6191 said:

Wouldn't argue with any of that but my suggestion was based on OP's quite specific requirements. As I recall he had replaced the power socket with a twin USB outlet but wanted it to be ignition controlled. I figured that even if the lighter socket was running at 20a there would be no risk (even to Jeep's infamous marginal wiring) in adding, say, a phone charger & GPS.

Coincidentally, I bought a new starter pack a couple of weeks ago, that has an alternative lighter socket plug (which I'd not seen before) - but I'd never use it, for no other reason than just doesn't seem right, so wouldn't feel comfortable with it.

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I have a dual USB adapter that has a voltmeter built in so you can monitor the battery. It also has a push button on/off switch. Might think of that, and wire it hot all the time and you have the option to turn it on when you want it.