New Switched Live

[lemmingzappa 75 1 Cars]

Where's the best place on the fusebox to wire in a new switched live? I need to add a cig socket behind the dash on a switched live, as I'll be plugging in a device which has to use the connector which converts it to a 5.5v output. The existing cig socket is perm live and I wouldn't mind keeping that free for sat nav's etc..

 

I also don't really want to add a socket onto the end of the stereo loom as I run gauges there. The plan was to add new wiring from the fusebox somewhere, with 5A rated inline fuse.

[pugpete1108 62 1 Cars]

I'd just tap in the to large switched live from the ignition barrel? Can't remember what wire it is though? Big orange one?

[lemmingzappa 75 1 Cars]

Is that already fused? If so, do you know what rating?

[pug_ham 245 3 Cars]

Why isn't the original wiring there?

 

I'd find someone breaking a car & ask them to remove the complete piece of loom you need from the fusebox to the cig lighter & use that so it will be fused, the ignition feed isn't fused.

 

g

[lemmingzappa 75 1 Cars]

The cig lighter wiring is already there, but the device I want to wire in permanently needs to be used in a cig socket and I want to keep the original one free for sat navs or phones. I could use the stereo wiring but also want to keep that free for other things (assuming that adding additional draw on a single cable makes it more likely to melt or blow a fuse?).

 

Can I not piggyback off the unfused ignition switch wiring and just add an inline fuse before the cig socket?

Edited January 16, 2013 by lemmingzappa

[pug_ham 245 3 Cars]

Can I not piggyback off the unfused ignition switch wiring and just add an inline fuse before the cig socket?

 

You could but why not piggy back off the current cig lighter instead if it'll be unused most of the time?

 

IIRC its a good thickness of wire or you could run an additional length of wire to the fusebox plug for the lighter socket, although you might still need to change the fuse to prevent it blowing when using both.

 

There is an unused spare socket in the fusebox so studying the haynes could mean you can wire it in & make use of it.

 

g

[lemmingzappa 75 1 Cars]

My current socket is a perm live. Is the spare slot on the fuse box automatically a switched live?

[pug_ham 245 3 Cars]

Looking at the haynes fuseboard diagram, both spare fuses are permanent feed & then run through the fuse to a relay socket.

 

Easy enough to test if you have a multimeter & you could have two spare fuse positions, #4 & #6.

 

g

[pugpete1108 62 1 Cars]

Just piggyback off the ignition wire then add an inline fuse? Job jobbed

[lemmingzappa 75 1 Cars]

After looking at the ignition wiring, the large orange wire is a perm live so unable to use that. But there is a wire which I think is 32A (the writing has scrubbed off) and is a switched live:

 

 

It's the red wire closest to the camera. Would this be ok to use as the Haynes shows it going to the tachymetric relay?

Edited January 17, 2013 by lemmingzappa

[Anthony 1,003]

32A comes from the brown multiplug under the dash to the tachymetric relay, and is a thin yellow cable.

 

There are both switched accessory (1st click of the key, goes off when cranking) and switched ignition (2nd click of the key, stays on when cranking) on the ignition barrel wiring.

 

Personally, I hate people hacking into the wiring there, but it's your call. I'd personally much rather just use an unused feed on the fusebox, which there should be several - the electric window feed is switched for example (if you're using keep fit windows) and there's numerous other ones in there that a couple of minutes with a multimeter will identify.

 

There's also a dedicated accessory feed in the middle-ish of the fusebox, labelled AC+ IIRC, which probably has the stereo (thick blue) plugged in at the moment.

 

How much current is what you're wanting to leave plugged in drawing exactly?

Edited January 17, 2013 by Anthony

[lemmingzappa 75 1 Cars]

There's also a dedicated accessory feed in the middle-ish of the fusebox, labelled AC+ IIRC, which probably has the stereo (thick blue) plugged in at the moment.

 

How much current is what you're wanting to leave plugged in drawing exactly?

 

I did spot the AC+ on the fusebox, it had a single thin light blue wire going to it and the pin next to it was unused. If I can use that empty pin then that would be great.

 

Not sure on the device figures itself, all I know is that the adaptor it has to use is a standard cig socket which goes from 12v to a 5.5v output for USB.

[Anthony 1,003]

The empty pin next to AC+ it is a permenant live IIRC.

 

USB current limit is 5A for charging, which at 5v means 25W. Most USB devices use significantly less.

 

25W at 12v (nominal) is a touch over 2A which is comparitively insignificant, and you should be able to piggyback on most circuits that use a thickish cable fairly safely.

 

(I am of course assuming that the 12v to 5v step down is 100% efficient, which it won't be, but it shouldn't make much difference)

[lemmingzappa 75 1 Cars]

Cheers for the advice, will have a ganders around the loom later tonight.

[pug_ham 245 3 Cars]

Personally, I hate people hacking into the wiring there, but it's your call. I'd personally much rather just use an unused feed on the fusebox, which there should be several - the electric window feed is switched for example (if you're using keep fit windows) and there's numerous other ones in there that a couple of minutes with a multimeter will identify.

 

I'm with Anthony on this, why hack / chop or scotchblock into existing wiring when there is a suitable unused fusebox feed which is a much better way to do things.

 

In one version of Haynes manuals I have it lists a front & rear cigar lighter.

 

After looking at another version of Haynes, fuse #4 could used for the driving lights but fuse #6 is still unused along with #12.

 

If only I had my owners handbook to hand.

 

g

[lemmingzappa 75 1 Cars]

Works great, used a spare switched pin on the fusebox and a 5A inline fuse. Thanks for the help guys!