Member Since: 28 Jan 2022
Location: Cambridge
Posts: 7
Installing trailer wire harness
Hi all,
I am so sick of trying to get this information from LR that I have reverted to you guys. I want to fit my Discovery 4 with trailer lighting sockets (probably just a 7 pin). I can easily buy a harness and fit it, but various sources suggest the following and I would like to know your experience/thoughts please:
- That when fitting the harness you must disconnect the earth terminal before fitting- is this true?
- Could removing the earth terminal create issues with the electronics? It says you may need to recalibrate the electric windows and other bits after disconnection
- Do LED trailer lights work correctly with the genuine LR harness? I gather not.
- I can buy a non genuine LED compatible harness elsewhere- but does this affect the LR warranty?
- After fitting the harness, many talk of a re-code of the ECU/BCM- but I gather this is not essential as is only for parking sensors, is this correct?
Sorry of this info is elsewhere, but I couldnt find it and surely many people have faced these same questions.
Any help gratefully received.
Jonny
8th Apr 2022 1:36 pm
Famousfive
Member Since: 12 Aug 2014
Location: Southampton
Posts: 1832
Hi Jonny,
you've come to right place answers in red below
That when fitting the harness you must disconnect the earth terminal before fitting- is this true?
For safety yes but not crucial
- Could removing the earth terminal create issues with the electronics? It says you may need to recalibrate the electric windows and other bits after disconnection
Windows and clocks might the only thing - but window reset is a 5 sec per window job so i'd say go for it
- Do LED trailer lights work correctly with the genuine LR harness? I gather not.
hmm not sure on this one - I think on a D4 you'd be ok
- I can buy a non genuine LED compatible harness elsewhere- but does this affect the LR warranty?
They would do anything to get out of a warranty claim so I would buy genuine but not sure warranty would be invalidated by fitting this?
- After fitting the harness, many talk of a re-code of the ECU/BCM- but I gather this is not essential as is only for parking sensors, is this correct?
Ideally you'd get the CCF (Car Config File) updated to tell it has a trailer - otherwise sensors will go off when parking is activated - more annoying than essential
Member Since: 06 Dec 2010
Location: Canberra
Posts: 1130
Like the D3, LED trailer lights will work OK BUT the low load will not trigger the car to do its thing eg trailer indicator on the dash, reversing sensors will still go off etc.
So you will need a pulse buster of some sort but unlike the D3 that requires one with both relays and resistors, the D4 only requires resistors.
8th Apr 2022 1:55 pm
jonny28
Member Since: 28 Jan 2022
Location: Cambridge
Posts: 7
Wow that was fast, thanks so much. Knew I should have come here earlier!
8th Apr 2022 1:55 pm
jonny28
Member Since: 28 Jan 2022
Location: Cambridge
Posts: 7
So is this not true, or is there risk of damage if you dont disconnect?
Click image to enlarge
8th Apr 2022 2:52 pm
al cope
Member Since: 08 Nov 2005
Location: Oldbury, WM
Posts: 10355
Never disconnected It on My 2 D3’s or 2 D4’s when connecting trailer loom. Never had any issues.
AlVolvo XC90 B5 Plus Dark
Gone - MY18 D5 HSE - Corris on 22's with Black Pack
Now gone - MY16 D4 SE Tech, Loire Blue, Almond Leather, Privacy, plus some other goodies.
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You will probably have issues with LED Lights, I did on a 2016 I did. Trailer indicator light will probably not work (legal requirement) reversing sensors will sound off.
And go for a 13-pin connector. It is a much better connector and adapters to 7-pin are cheap. You will not regret going 13-pin.
Regards,
Steve
9th Apr 2022 8:32 am
nigethecat
Member Since: 11 Sep 2016
Location: Marnoch
Posts: 4244
As above, 13 pin gives you the option to charge the car through the towing socket (adapter available from the forum shop), and will future proof the car as all trailers from 2013 (I think) were fitted with 13 pin sockets (caravans even earlier).
I've fitted three or four harnesses and never disconnected the battery and not had an issue. Also no issues with windows not working after(think it's a case of CYA by LR). Genuine wiring will mean everything works straight off, aftermarket may need a config update..
The D3 and D4 don't like led trailer lights, either a box on the trailer or in the car solves this issue. There are some "how to's" if you search...I want to see the sweets before I get into your windowless van... I'm not stupid!
Corris Grey D4 Commercial SE 2016
Zermatt Sliver 2007 D3 SE manual (gone)
Indus Silver D4 HSE 2015 (gone)
Bonatti Grey D3 HSE 2006 (gone)
White D3 S (LHD) 2007 (gone)
Firenze Red D4 HSE 2014 (gone)
Black RRS 3.6TDV8 2008 (gone)
Rusty Green Defender 110 1997 (gone)
Black FL2 HSE 2013 (gone)
9th Apr 2022 9:33 am
Grinder75
Member Since: 24 Apr 2018
Location: Colchester
Posts: 14
Hi, I have a disco 4 - 2016. it did not come with the tow pack, so i had the LR dealer fit the 13 pin socket.
i have had a disco before and when indicating with a trailer connected, got an indicator on the dash of a trailer.
not on this one. I have looked at the manual and it says that the trailer lamp should light up as a bulb check on ignition, but nothing.
I cannot see I have a trailer indicator. if I do perhaps its a dead dash bulb - where on the dash should i look - what position on the rev counter or speedometer
i have an IIdtool - and all of the trailer options are now enabled
28th May 2022 6:18 pm
nigethecat
Member Since: 11 Sep 2016
Location: Marnoch
Posts: 4244
Does your trailer have LED lights? If so the voltage draw won’t be enough to trigger the dash light. Check the answer above as well.I want to see the sweets before I get into your windowless van... I'm not stupid!
Corris Grey D4 Commercial SE 2016
Zermatt Sliver 2007 D3 SE manual (gone)
Indus Silver D4 HSE 2015 (gone)
Bonatti Grey D3 HSE 2006 (gone)
White D3 S (LHD) 2007 (gone)
Firenze Red D4 HSE 2014 (gone)
Black RRS 3.6TDV8 2008 (gone)
Rusty Green Defender 110 1997 (gone)
Black FL2 HSE 2013 (gone)
28th May 2022 6:31 pm
Gastón did castelnuovo
Member Since: 15 Apr 2022
Location: Argentina
Posts: 15
Hello mates! Have anyone tried PF Jones trailer wiring kit? It comes either in 12 and 7 pin. It's about £80.
Thank you!
9th Jun 2022 10:57 am
nigethecat
Member Since: 11 Sep 2016
Location: Marnoch
Posts: 4244
PF Jones are well respected and their kit is of good quality, I'd personally go for the 13 pin kit
but that very much depends on the standard trailer connections in Argentina (could be mostly 7, mostly 12 (n&s), or 13...) 13 allows you the option to charge the trailer you are towing while driving or to use a plug in charger (adapter available in the forum shop) to charge the car through the socket...
All kits should be plug and play with the connections already in the car in the rear (drivers side for you) cubby.. a very simple install I want to see the sweets before I get into your windowless van... I'm not stupid!
Corris Grey D4 Commercial SE 2016
Zermatt Sliver 2007 D3 SE manual (gone)
Indus Silver D4 HSE 2015 (gone)
Bonatti Grey D3 HSE 2006 (gone)
White D3 S (LHD) 2007 (gone)
Firenze Red D4 HSE 2014 (gone)
Black RRS 3.6TDV8 2008 (gone)
Rusty Green Defender 110 1997 (gone)
Black FL2 HSE 2013 (gone)
9th Jun 2022 12:01 pm
Gastón did castelnuovo
Member Since: 15 Apr 2022
Location: Argentina
Posts: 15
Both 12N and 7 pin are the most common type of connectors here. My concern was the quality and compatibility with D3 factory connections, I don't want to touch or modify anything due to the "sensitivity" of our beloved mechanical member of the family!
Hope to start enjoying the car after changing both LPFP and HPFP last week.
Thank you very much I Niget!
Ps. I'm getting PF wiring from maltings4x4 as it is about £56!
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answers in red below
