Member Since: 24 Oct 2017
Location: Aberdeenshire
Posts: 48
Trailer Detection - Trailer with LED lights. MY2016 L319
Hi guys,
I've exhausted the search function looking for guidance on this, lots of historical issues with LED's on the Disco 3 and early 4's, but more to do with strobing on the lamps rather than trailer detection.
Anyway, we've just taken delivery of anew IWT trailer with the LED light package. Twin Axle, 3500Kg.
The car (MY2016 L319) can operate the LED lights fine but it does not detect the trailer is connected
So amongst other thing this mean that there is: -
1. No automatic disabling of rear PDC when reversing with trailer.
2. No disabling of Blind Spot monitoring (constantly flashing in sides mirror - presumably thinking trailer is trying to overtake the car!)
3. No automatic disabling of car fog light.
4. No trailer steering/Tow assist when reversing (bit of a gimmick anyway, probably won’t even stick on a target on this trailer.)
5. No additional trailer indication symbol in cluster whin when indicating
But most importantly: -
6. No trailer stability control. I’ve read a couple of posts that state that the trailer stability control is always enabled but I don’t believe this to be the case. I am certain that the vehicle stability control is different with a tailer connected vs without.
In any case I've got round this in the past by bridging PIN 3 and PIN 12 in the trailer plug however not sure if Disco supports this now.
Has anyone tried bridging the pins in their MY2016 Discovery 4? The car can detect trailers with incandescent bulbs fine, obviously detecting the circuit correctly through the filaments.
Member Since: 24 Oct 2017
Location: Aberdeenshire
Posts: 48
Thanks swansty,
Yes, the car has had a towbar from factory and has the towbar functions enabled.
Additionally, everything works well as expected with a filament bulb trailer, but not with the LED version.
When I say as expected - the normal trailer specific functions work when connected, inc the trailer detection (i.e. the car displays (Has a trailer been connected? etc) And also the addition indicator flashes on the dash with the regular lamp.
You can also program the dimensions of 3 or 4 trailers for the tow/reverse assist (using the surround cameras etc).
if you're using LED bulbs, you'll need to put a load resistor across the positive feed for the bulb and the ground wire (negative side).
Its because LED's draw so little current compared to a cobverntional bulb, the systems on the Disco "cannot see it"Si
2016 Disco 4 SE Tech
2019 Fiesta ST3
2021 GBS Zero
5th Jul 2021 7:12 pm
Peter H
Member Since: 07 Apr 2021
Location: Worcestershire
Posts: 5
Easiest option is to replace with conventional bulbs.
5th Jul 2021 8:20 pm
Farmer Chalk
Member Since: 07 Mar 2013
Location: Independent Republic of Kentishshire.
Posts: 4156
As Santa Cruz says…. You can either wire some load resistors between the bulbs to simulate the higher load required for the car to recognise the expected current draw or purchase a unit similar to this …
Member Since: 11 Sep 2016
Location: Marnoch
Posts: 4142
Or alternatively sell the trailer with led lights cheap to someelse living in Aberdeenshire I want to see the sweets before I get into your windowless van... I'm not stupid!
Corris Grey D4 Commercial SE 2016
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Indus Silver D4 HSE 2015 (gone)
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White D3 S (LHD) 2007 (gone)
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5th Jul 2021 10:18 pm
Russellg
Member Since: 24 Oct 2017
Location: Aberdeenshire
Posts: 48
Thank for the feedback guys,
I know there are work arounds with load resistor or bulbs etc, but I’m specifically wondering if the Disco supports bridging the pins.
We move the trailer with more than one vehicle so not really keen on swapping bubs etc, the benefit of having the LEDS is that they are dual voltage working both with 12v and 24v.
On my D3 I had all manner of issues with an LED equipped bike rack, easiest thing was to change the bulbs to stop the hyper flash. Actually, had the same issue with a Shogun on the same bike rack but just changing the reversed, number plate and fog to a build sorted that, not so on the D3 though.
The D4 powers the trailer okay, no strobing or hyper flashing but it would be great if knew it was there to disable all the other stuff. In fact, tonight its quite foggy in the NE and the reflection off the ladder rack from the D4’s fog light is distracting to say the least!
In any case I’ll have a go at bridging the pins this week and feedback (if they’re not already bridged by IWT of course). If they are I’ll add in some bulbs into one circuit and report back my findings.
5th Jul 2021 10:40 pm
Russellg
Member Since: 24 Oct 2017
Location: Aberdeenshire
Posts: 48
nigethecat wrote:
Or alternatively sell the trailer with led lights cheap to someelse living in Aberdeenshire
As you know, almost NOTHING is cheap in Aberdeenshire!
Except maybe banter of course.
5th Jul 2021 10:41 pm
Kelvo
Member Since: 07 Aug 2015
Location: Perth WA
Posts: 264
Russellg wrote:
Thank for the feedback guys,
I know there are work arounds with load resistor or bulbs etc, but I’m specifically wondering if the Disco supports bridging the pins.
Bridging pins will only blow fuses.
Two load resistors, and a double pole switch mounted to the boot side panel is all you need. Not towing switch stays off, towing a trailer with incandescent lights switch stays off, towing a trailer with LED lights switch is turn on.
Member Since: 23 Jun 2009
Location: High Wycombe
Posts: 570
I have MY16 D4 from new and supplied with a fixed tow bar.
When a trailer is connected it does not disconnect the PDC regardless of the type of light bulbs in the trailer.
The other quirk it has is to engage the PDC as soon as you put it into neutral.
6th Jul 2021 7:18 am
Russellg
Member Since: 24 Oct 2017
Location: Aberdeenshire
Posts: 48
Thanks guys.
Looking at the JLR wiring diagram of the 13-pin socket there is not connection from the car to socket on PIN-12
That suggests no point attempting it.
6th Jul 2021 8:52 am
Russellg
Member Since: 24 Oct 2017
Location: Aberdeenshire
Posts: 48
Hanechdene wrote:
I have MY16 D4 from new and supplied with a fixed tow bar.
When a trailer is connected it does not disconnect the PDC regardless of the type of light bulbs in the trailer.
The other quirk it has is to engage the PDC as soon as you put it into neutral.
Mine also engages PDC in neutral. It’s not hardship of course to hit the PDC off button, I always engage low box for towing something heavy slowly up a slope.
Does your car ask if you to select a trailer when you hook up? If I ignore that prompt the PDC does not get disabled in reverse.
6th Jul 2021 8:56 am
nigel207
Member Since: 26 Mar 2009
Location: Nottinghamshire
Posts: 1344
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