Member Since: 16 Sep 2019
Location: Newcastle Under Lyme, Staffs
Posts: 171
Strange Trailer lighting issue
Hi
Connected my trailer to my 2005 D3 SE for the first time yesterday. The trailer has LED lighting.
I noticed yesterday that as soon as I connect the trailer plug to the car, the rear indicators on the trailer flash dimly together at about a 1 second rate. Everything still works OK, all the lights on the trailer work, including the indicators that flash bright and correctly when you indicate on the car.
I'm sure it didn't do this before on my Disco 2, but I can't be 100% sure.
Any ideas ??
Thanks
Mat2005 TDV6 SE Auto
Cairns Blue
25th Apr 2020 8:49 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10676
It’s normal for D3 and this generation of cars.
They don’t like LED indicators as they use the bulbs to detect a presence of a trailer.
Which then stops you messing with suspension height and should in theory disable park sensors.
Lots of posts about this.
With leds it won’t do that and you get annoying flash
25th Apr 2020 9:07 am
Farmer Chalk
Member Since: 06 Mar 2013
Location: Independent Republic of Kentishshire.
Posts: 4195
It’s all to do with the resistance between normal bulbs and the led bulbs...your D3 has sensitive electrics which measure the resistance around the vehicle...it detects that it has a trailer plugged in but is confused because it’s reading values that it does not equate...because LEDS run minimal resistance...hence your problems...there are devices available that can plug in between your towing electrics which will solve this...
25th Apr 2020 9:22 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10676
If the car has detected a trailer fitted it will flash a green light at the bottom of the dash when indicators used
25th Apr 2020 9:30 am
matgriff
Member Since: 16 Sep 2019
Location: Newcastle Under Lyme, Staffs
Posts: 171
OK thanks.. I should have searched the forum first.... oops
Yes I wondered why it didn't light the trailer light on the dashboard, which my disco 2 did.
I'll just add some resistors to increase the current draw and fool the car into thinking it's got normal bulbs connected.
Thanks
Mat2005 TDV6 SE Auto
Cairns Blue
25th Apr 2020 5:06 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10676
You would think load resistors would work.
But ppl have reported it doesn’t. So good luck.
25th Apr 2020 5:37 pm
Farmer Chalk
Member Since: 06 Mar 2013
Location: Independent Republic of Kentishshire.
Posts: 4195
It’s worth a go.....but the plug in device between the two plugs is probably easier..
I had this problem with my horsebox build when I converted to rear LED lights....played havoc with the original truck wiring... I did solve it by placing resistors across the feeds to each led unit...
25th Apr 2020 7:54 pm
matgriff
Member Since: 16 Sep 2019
Location: Newcastle Under Lyme, Staffs
Posts: 171
Yeah, the trailer fitted indicator lamp on the dash must be able to be made to work with some resistors.... electrically speaking the only difference between a resistor and a bulb is that a resistor doesn't give out any light.
I'll take a good look at the wiring diagrams this week.
The pulsing of the LED indicators must be some kind of circuit continuity pulse check, that you wouldn't normally see in a standard bulb as it's so short it wouldn't light, but an LED is triggered by it ?
A D3 needs relays and resistors to stop the flicker. A D4 will not cause LED trailer lights to flicker, you only need resistors if you want the D4 to know a trailer is connected.MY14 TDV6
26th Apr 2020 2:24 pm
mnotting
Member Since: 26 Mar 2020
Location: Carina Heights
Posts: 4
Flickering LED trailer lights fix Disco3
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Click image to enlarge
Mat
Quicker to buy an adapter cable between the car and trailer ($231) or if you are handy with tools and can follow a wiring diagram you can make one yourself. Some people put it in the car for use on all trailers but need to switch it off when not in use. I bought a new trailer so fitted a box to the trailer instead which has the wiring and plug coming out of it. My setup is attached. 2 X 6 ohm 50w resistors and 2 X 12V relays from Repco and an aluminium box and cable glands from Jaycar. Wiring diagram same as in previous posts. Note the Stop and brake light wiring is straight through the box so not shown in the diagram.
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Click image to enlarge
11th May 2020 4:50 am
FidoNick
Member Since: 18 Jan 2021
Location: Purton, Wiltshire
Posts: 131
Kelvo wrote:
A D3 needs a ‘pulse buster’ to stop the LED flicker. It is basically two resistors and two relays.
Click image to enlarge
Wiring diagram taken from AULRO
Wiring diagram worked a treat (thank you! ) and has 'fixed' the blinking indicators etc. One thing to note is the resistors will get rather warm when in prolonged use - for example with the hazards flashing. The image below was taken after probably ten minutes of hazards on the go and continued to rise a further 5 degrees:
In normal use, the temperature shouldn't be a problem, but if you're stranded with the hazards on the go you might want a way to bypass the mod - or ensure the resistors have a suitable heatsink. Mine were simply held in place with hot glue while it was under test. The term 'chocolate teapot' seems apt here . I'll be getting a heatsink before it's put into real use.
28th Dec 2021 9:29 pm
Kelvo
Member Since: 07 Aug 2015
Location: Perth WA
Posts: 264
Instead of the plastic box use an aluminium one and screw the resistors to that on opposite sides of the box. Just fixing the resistors to a heat sink in your plastic box isn’t going to allow the heat to escape the box.MY14 TDV6
28th Dec 2021 10:44 pm
FidoNick
Member Since: 18 Jan 2021
Location: Purton, Wiltshire
Posts: 131
You're absolutely right - I have thought of fixing it to a heatsink which is externally exposed. I might see if I can find a suitable aluminium box instead.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
) and has 'fixed' the blinking indicators etc. One thing to note is the resistors will get rather warm when in prolonged use - for example with the hazards flashing. The image below was taken after probably ten minutes of hazards on the go and continued to rise a further 5 degrees:
. I'll be getting a heatsink before it's put into real use.
