colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
  
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| Towing Electrics QUESTION |
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Hi I have recently bought a 2005 Disco 3 (diesel) with what appears to be factory fitted tow sockets (black and white).
I tried them on my trailer and the electrics had numerous problems. Using a cheap trailer electrics tester the Disco 3 reported faults on the green and yellow wires (R and L indicators). Using the same tester on my Disco 2 all lights on the tester were fine - no problems. The trailer has no known issues.
I was suspicious of the actual socket on the car itself so replaced the existing black socket. Exactly the same result - two lights on the tester didn't light up (green and yellow), shame that I wasted a good LR socket!
I tried my tester on a friend's Disco 3 and again - the same result as mine - two lights out , green and yellow. I suspect that they have been towing with no problems.
Are there any gotchas that I may be unaware of? Is my tester a POS? Any tips on where to look for problems? Looking under the car the wiring looks like Land Rover original stuff and seems in pretty good condition. I was concerned that the swinging weights under the rear bumper might have chaffed wires but I couldn't see any damage.
Any next steps or ideas most welcome. Thank you in advance.
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 27th Jan 2022 5:58 pm |
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SantaCruz
Member Since: 22 Jan 2012
Location: Salisbury, Wiltshire
Posts: 564
 
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There's a separate fuse box for the tow electrics in the boot, behind the LH removable panel. Also very worth checking the connectors there too. Si
2016 Disco 4 SE Tech
2019 Fiesta ST3
2021 GBS Zero
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| 27th Jan 2022 6:45 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10635
 
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Green yellow are indicators if that’s what you mean.
And are unfused!
The green yellow are on a separate connector behind the rear left light.
So I would first remove that and check it and for power present there.
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| 27th Jan 2022 7:20 pm |
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colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
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Thanks for the replies - I hadn't realised that the towing wiring all connects up behind the light and in the rear left compartment.
I shall take another look in better light tomorrow and when its a little warmer. The connectors look pretty dirty. I ma tempted to disconnect and remove the wiring - check for any damage, clean it and reconnect it.
RE green/yellow - yes I did mean R&L IND
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| 27th Jan 2022 8:26 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10635
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The tow loom is in 2 parts.
It joins by the light.
And are 3 connectors
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| 27th Jan 2022 8:34 pm |
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aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2463
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These vehicles will not tolerate LED bulbs without a ballast resistor fitted, the tester will have LED's and this is why its picking up faults Andrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
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| 27th Jan 2022 8:54 pm |
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colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
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Thank you all again - good point about the LEDs in the tester!
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| 27th Jan 2022 10:28 pm |
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colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
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Well I found the connectors and can see that the loom outside the car disconnects behind the bumper. The wiring all looks really neat and was probably factory fitted (all had Land Rover tags on). I cleaned all connectors (that feed white plug and black plug) , checked for any damaged cables and checked all relevant fuses (glove compartment and behind the nearside rear light) , earthing points - all seems good.
I got exactly the same result, RH indicator flashing with the right hand rear light on the trailer , LH indicator fine. No lights lighting up on the trailer other than that though. I did notice the trailer has an LED fog light could this upset things even if it was left off?
The trailer seems to work fine with my Disco 2 else I would be more suspicious of the trailer itself.
Is there anything on the car that needs setting? Software? I suspect the towing sockets have not been used recently and possibly ever at all.
If anybody has any more ideas please fire away.I am reluctant to start pulling the car electrics apart as my gut feel is they look so clean and neat I'd be surprised if they were at fault, well certainly behind the nearside rear light area. Thanks again.
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| 29th Jan 2022 7:33 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10635
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Led fog light won’t be an issue.
Explain what the problem is again ?
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| 29th Jan 2022 7:44 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10635
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Check inside behind the rear light.
There are more towbar connectors there
Use a test light or meter in the rear fuses with the lights on to check for power.
5A fuses do the tail/night lights
7.5A does brake and fog lights
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| 29th Jan 2022 7:48 pm |
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colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
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Thanks Pete K at least something else I can try.
It does look really neat wiring - there were two warning triangles stuffed in that compartment - I guess they could have moved something.
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| 29th Jan 2022 8:02 pm |
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colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
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Well I tested with a multi-meter at the loom plugs and the sockets. I tested continuity. All seems fine to me.
The trailer works perfectly with Disco 2 (manual with no white socket) but will not play ball with the Disco 3 (automatic with black and white sockets)
I am inclined to turn my attention to the trailer but still cannot understand why all is good with my D2 but not the D3. 
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| 30th Jan 2022 2:35 pm |
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aja4x4
Member Since: 14 Apr 2019
Location: Westbury
Posts: 2463
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By law you have to have an audible or visual indication that your indicators are working when the trailer is connected. The D2 and D3 use different methods of detecting that a trailer is connected the method used on the D3 will not tolerate LED bulbs in the indicators due to the low resistance.
You can get around this a number of ways the most common ways are to fit normal bulbs to the indicators or to fit ballast resistors to the trailer wiring Andrew
D3 2.7tdv6 2005
D4 3.0 SDV6 Commercial died and gone to LR heaven
D5 3.0 SDV6 HSE
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| 30th Jan 2022 2:56 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10635
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What I don’t understand from the poster is whether the red lights are working in the trailer with the D3 (brake tail etc)
The “problem “ is unclear to me. And therefore difficult to help
We hear the trailer has an led fog light. But what about the other lights ?
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| 30th Jan 2022 3:46 pm |
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colinp007
Member Since: 20 Jan 2022
Location: Bletsoe
Posts: 26
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Hi,
All trailer lights are bulbs bar the trailer fog light which is LED.
The trailer has small side lights front and back.
Disco 3 - no small sidelights at all , rear lamps RH Ind and RH lamp both at once now, LH Lamp better but then flashes a bit when LH Ind selected - didn't try the fog lamp as LED. Rear lamps in general may not be full brightness (maybe).
Disco 2 - all perfect.
I will be looking for an earth fault on the trailer next. Tried the Disco 3 with a bike rack lighting board - brakes, rear lamps and indicators all AOK.
Thanks for all replies sorry if I have wasted any body's time - I have certainly wasted a lot of my own!
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| 30th Jan 2022 5:18 pm |
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