Member Since: 29 Oct 2011
Location: Staffordshire
Posts: 511
Towing electrics puzzle
Hi, I bought an after market towing electrics kit for my D4. There are a pair of bridging harnesses that connector between the car wire harness and the lamp.
This little harness is fitted to both rear lamps and every connection is carried across except the red and yellow pin for the rear fog lamps. The car pin is just blanked off, consequently the rear fogs dont work.
You can see the little white blank pin in the plug.
On the new lamp side connector there is a single wire that comes out of both sides and these wires both connect to the fog lamp pin of the light then to the fog lamp pin of the trailer socket.
Its the wire to the right of the blanking plug in the photo.
So I am guessing that this means that the fog lamps on the car take their new feed from somewhere else. Seems odd. Any idea why this would be the case? The fogs dont work on the car at any time.
When I remove the bridging harness and connect the original plug the fogs now work. So I have left them disconnected.
When I connect the trailer board it gets very interesting.
Connect board then start engine and trailer fog comes on, car fogs dont work, turn off the engine, disconnect trailer restart car and car fogs now work. I think this is expected.
Connect board , start car trailer fog works and car fogs dont work, unplug board with engine running and car fogs will still not work.
Connect trailer with engine running, car and trailer fogs work, disconnect with engine running and car fogs still work.
The upshot of all of this is I have just left the link harness off now as not needed.
Does anyone else recognise the work not work pattern above?Discovery 4 3.0 HSE 2010 year. I like it a lot. Now with winch 😂
20th Oct 2019 5:04 pm
Kelvo
Member Since: 07 Aug 2015
Location: Perth WA
Posts: 264
Connect board then start engine and trailer fog comes on, car fogs dont work, turn off the engine, disconnect trailer restart car and car fogs now work. I think this is expected. This is correct.
Connect board , start car trailer fog works and car fogs dont work, unplug board with engine running and car fogs will still not work. This is correct. On a D4 the car pulses the trailer connection on startup only, this is when it detects if a trailer is attached. This is the reason why LED trailer lights do not flash like they do on a D3 that is always pulsing the trailer connection.
Connect trailer with engine running, car and trailer fogs work, disconnect with engine running and car fogs still work. This is correct. On a D4 the car pulses the trailer connection on startup only, this is when it detects if a trailer is attached. This is the reason why LED trailer lights do not flash like they do on a D3 that is always pulsing the trailer connection.MY14 TDV6
20th Oct 2019 10:44 pm
charlietortoise
Member Since: 29 Oct 2011
Location: Staffordshire
Posts: 511
Fog lights
So all is as it should be then. Thanks for confirming this. So whatever those little links are for is surplus to requirements.Discovery 4 3.0 HSE 2010 year. I like it a lot. Now with winch 😂
21st Oct 2019 4:48 am
riverblanche
Member Since: 31 Aug 2010
Location: retford'ish
Posts: 2227
Hi,
have you tried the parking sensors yet
you mention the trailer board not sure if you have put an actual trailer on and selected reverse, from memory they should be like the rear fogs when the electrics are connected it disables the rear pdc
Oh and the winch is not THAT big you need a trailer Transit! 2019
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21st Oct 2019 9:19 pm
JackNorris
Member Since: 06 Jul 2012
Location: Beds/Bucks Border
Posts: 1879
Mine was like this, its a quick and easy way of disabling the fog lights when you have a trailer connected.
It uses a ring in the socket with breaks the connection when a plug is pushed in.
Although this bit throws me - - > Connect board , start car trailer fog works and car fogs dont work, unplug board with engine running and car fogs will still not work.MY2023 Discovery 5 R-Dynamic 3.0
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22nd Oct 2019 6:37 am
charlietortoise
Member Since: 29 Oct 2011
Location: Staffordshire
Posts: 511
riverblanche wrote:
Hi,
have you tried the parking sensors yet
you mention the trailer board not sure if you have put an actual trailer on and selected reverse, from memory they should be like the rear fogs when the electrics are connected it disables the rear pdc
Oh and the winch is not THAT big you need a trailer
Discovery 4 3.0 HSE 2010 year. I like it a lot. Now with winch 😂
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