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ScarboroughSeadog

Member Since: 21 Jul 2022
Location: Scarborough
Posts: 110

2013 Defender 110 Puma 2.2 DCPU Keswick Green

Wiring into battery junction box

Looking to take an ignition live for switched (via relay) heated seat feed from the under seat fuse box.
FL2 looks the obvious choice as this would have supplied any factory fitted seat heaters.
The question is, how to actually connect in? Can I use a piggy back fuse connector at FL2?
Or better to lift out the whole box and splice in underneath to the wire supplying FL2?

Feeding negative connection either to chassis earth or batt negative.
Planning to have the relays in the under seat box and switches at cubby box

Alternative is to take positive straight from battery but with obvious risk of battery drain if accidentally left on.

Haven’t just found the info I need (ie best way to connect in) from existing threads.

Click image to enlarge

Thanks

12th Sep 2022 1:05pm

jpboost

Member Since: 13 Apr 2021
Location: Gatwick
Posts: 377

2014 Defender 110 Puma 2.2 SW Keswick Green

I was looking into this a while back (although for a small amplifier, not heated seats).

When I was looking at it, I got to the point where I thought:

Piggy back fuse connections should work fine, and be easy/quick, but I think they're a bit ugly and look like a bodge...

It should be easy to add the needed wires into the back of the fuseboard if needed, but I didn't get to the point where I worked out what connector I needed. In other cars they're typically just a female spade connector, but I didn't check.

I ended up taking a feed directly from the battery but that decision was due to current draw/cable size rather than being unable to use the existing fusebaord.

12th Sep 2022 2:28pm

macfrank

Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1111

2015 Defender 110 Puma 2.2 SW Keswick Green

Have you checked if F22 and F23 are in place under the steering wheel (the CJB)?
Those are two 10A fuses wired to the LH and RH seat heater switches.
May be easier to piggy bag those than a JCASE fuse or to do the splicing underneath the BJB?

Also, maybe food for thought, the wire coming off FL2 ends at the window lift relay in the CJB (a brown-red 4mm^2 wire). That relay is ignition-switched and provides the power coming off FL2
via F14 (10A) to rear washer and wiper
via F24, F25 (20A) to window lift switches
(in addition to F22 and F23).

12th Sep 2022 3:53pm

ScarboroughSeadog

Member Since: 21 Jul 2022
Location: Scarborough
Posts: 110

Thanks

Will check the CJB tonight but I have pauper spec, so may not have the seat heater fuses/wiring fitted. Also a bit of a pain to feed the wiring back from there (under a fitted acoustic mat)

Now talking my language though- a brown/red wire. F14, F24 &25 not present/used on my model (twin cab- don't have rear window). I can see that FL2 provides for those functions though (I do have elec windows).

What I really need to know is where to access and splice into that brown/red (or other suitable ignition +) wire......

12th Sep 2022 4:24pm

macfrank

Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1111

Didn't check for other suitable ones, but this should be it:

Click image to enlarge

Click image to enlarge

But PLEASE, "check twice, cut once" - don't blame me for anything

(actually the encircled one is C3768, the "other half" of the connector)

12th Sep 2022 4:37pm

ScarboroughSeadog

Member Since: 21 Jul 2022
Location: Scarborough
Posts: 110

Ok great- checked all this out on the vehicle and found the brown/red wire. Checked underneath and it routes from FL2.
Plan is to splice the two (fused) + heater connections into this wire at an accessible point ideally with heat shrink solder connectors.
Do I need to disconnect battery first (which hopefully won’t upset the alarm or radio) if no keys in ignition?
Will try and find a suitable earth connection in the same under seat box. Maybe the fuse box bolts (unless that’s a bad idea?).
That should do the job- thanks for your help.

Just FYI I do have the fuse slots for the factory fit heated seats in the other fuse box under the wheel- but couldn’t see if these were actually wired.

Just out of interest- where did you source your diagram/part nos etc?

12th Sep 2022 7:16pm

macfrank

Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1111

um, sorry, somehow I was absorbed with FL2 and totally overlooked your inital sentence
>Looking to take an ignition live...
FL2 is NOT ignition switched

It's permant live. Only after the window-lift relay it's ignition switched, as I wrote above.
I even think all FL fuses are permanent live.
I'll get back to you tomorrow.

For the wiring docs search for user dgardel, you'll find a link to MY2012ff. Defender pdfs.

12th Sep 2022 8:34pm

macfrank

Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1111

ok, again sorry for the confusion. The white wire in C3769/3768 is ignition switched.
FL1 provides power to the ignition switch, from where the white wire is coming back into the seat box (white also branching off under the dash to the fuses there).
In the seat box White routes to F9, F10, F11 and F12.

In theory it should be ok to take the power for your heated seats off that White. Original wires for the heated seats each are only 1mm^2, even 0.75mm^2. But. Personally I wouldn't feel too confident about it. Partly it may be just me, because I always think LR should have chosen all power wires to be at least one step larger. Second, if you cut White, you're interfering with the stuff behind F9..F12. It's front wiper, reverse lamp, speed sensor and an ignition sense signal for the ECM. It's my feeling, that I wouldn't want to interfere with ECU-related circuits.
Again in theory, I'd rather use an ignition signal (small current), say tapped off F10 (the reverse lamp switch) and use that to switch a relay to provide power to the seats. Power could come from the brown/red wire (this only 'interferes' with the relay which is used for window lift, rear washer and heated seats anyway; nothing related to ECM or speedo).

13th Sep 2022 6:44am

ScarboroughSeadog

Member Since: 21 Jul 2022
Location: Scarborough
Posts: 110

No problem- all part of the discovery process! Will have a look at this again. The ‘backstop’ option is wiring the seat heaters direct to battery, but the risk is they get left on accidentally and drain the battery- hence the need for a wire that is switched live by the ignition.

Will have another look at what you say, and perhaps try and find an ignition live which serves only a basic function to tap into. I also wonder if there are any spare/unused wires in the loom.

This is one of those little issues that is more of a hurdle than it appears!
(Things were more basic when I re-wired the series 3!)

13th Sep 2022 9:03am

mwestcrew

Member Since: 09 Dec 2019
Location: South Warwickshire
Posts: 287

2011 Defender 130 Puma 2.4 HCPU Baltic Blue

You could wire direct to the battery and use a timer relay like the one used for the heated screen. That way there is no risk of accidentally draining the battery.

Or use a low current ignition feed which are easily available to energise the relay with the load directly to the battery. 2011 130 Utility Body
2005 110 Van

13th Sep 2022 10:37am

rustandoil

Member Since: 08 Sep 2012
Location: Cotswolds
Posts: 819

2005 Defender 110 Td5 XS DCPU Bonatti Grey

"Or use a low current ignition feed which are easily available to energise the relay with the load directly to the battery."

I think this is what I would do

13th Sep 2022 10:55am

LandRoverAnorak

Member Since: 17 Jul 2011
Location: Surrey
Posts: 11324

Isn't a low current ignition feed what the OP is asking about? It's where to find one that's the trick. Darren

110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak

"You came in that thing? You're braver than I thought!" - Princess Leia

13th Sep 2022 11:00am

rustandoil

Member Since: 08 Sep 2012
Location: Cotswolds
Posts: 819

Ah Right, yes you are correct, he's looking for it under the seat....my bad

13th Sep 2022 11:03am

macfrank

Member Since: 05 Nov 2015
Location: somewhere in the north
Posts: 1111

ScarboroughSeadog wrote:
No problem- all part of the discovery process!
...
This is one of those little issues that is more of a hurdle than it appears!
(Things were more basic when I re-wired the series 3!)

Indeed.
fun fact: Why is there a front wiper relay in the seat box? Well, that wiper power relay will be cut off by the inertia switch in case of an accident. How thoughtful. So if you're hanging upside down behind a shattered windscreen the last thing you want is the wiper poking an eye out on top of it all

13th Sep 2022 11:41am

ScarboroughSeadog

Member Since: 21 Jul 2022
Location: Scarborough
Posts: 110

mwestcrew wrote:
You could wire direct to the battery and use a timer relay like the one used for the heated screen. That way there is no risk of accidentally draining the battery.

Or use a low current ignition feed which are easily available to energise the relay with the load directly to the battery.

Timer relay and direct to battery feed might work- what spec relay do I need. Do I fit that inline with the switch or the battery cable? Or do I replace the heater loom relay with a timer relay? Any chance you could spell out what’s required?

The supplied Exmoor trim heater loom only has the fused positive and a negative wire- there is no separate ignition feed wire (I was planning to connect the loom positive to the ignition feed)

Thanks.

13th Sep 2022 12:34pm

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