Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
  
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| D4 Brake Lights Not Working |
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Hi all. First post ! New owner having just bought a 2012 HSE on Sunday and it's displaying "character" already.
After I got it home, reversing into the drive and seeing the car's reflection in the lounge window, I noticed the driver's side brake light was not working. Passenger side & high level OK.
On Monday, both sides not working, but high level OK.
Monday evening, after using it, passenger side not working. Driver's side & high level OK.
On Tuesday, we're back to both sides not working. High level still OK.
And to clarify - all other lights are working fine.
Checking voltage at the connectors showed a curious result - brake & indicator both show a constant ~7 Volts regardless of whether they're "on". The indicator somehow still works though ??? Other sections get 12V and work fine. The tail/brake/indicators are the LED type, btw.
Where do I go next ???
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 25th Sep 2024 8:29 am |
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Gary_P
Member Since: 03 May 2016
Location: Kent
Posts: 1664
 
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Having just purchased it, I would have thought your first recourse is to the seller?
Hope you get it sorted. Gary
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Discovery 4 HSE 2016MY
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| 25th Sep 2024 9:24 am |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 13018
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Brake switch is known to produce odd behaviour but I'm pretty sure it's not involved here.
Have a look in left-hand cubby hole in the boot (not the one with the jack in it * ) and see if a trailer-lighting modification has been done/removed would be my first guess.
* whilst you're in the boot, find the jack and bin it. buy something that can actually jack the car up safely instead. .
Dean
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2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer  ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
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| 25th Sep 2024 10:48 am |
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Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
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Gary_P wrote:Having just purchased it, I would have thought your first recourse is to the seller?
Hope you get it sorted.
Private sale, so no. I checked all the other lights while I was there but not the brake lights. D'oh.
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| 25th Sep 2024 11:30 am |
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Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
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Hardware wrote:Brake switch is known to produce odd behaviour but I'm pretty sure it's not involved here.
Have a look in left-hand cubby hole in the boot (not the one with the jack in it * ) and see if a trailer-lighting modification has been done/removed would be my first guess.
* whilst you're in the boot, find the jack and bin it. buy something that can actually jack the car up safely instead.
Good suggestion.
Also, I've seen Sprinter bottle jacks recommended. Is that the go-to choice ? I already have a trolley jack for use at home.
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| 25th Sep 2024 11:31 am |
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Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
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Possible dumb question - but do the brake / indicator LEDs expect +12V to illuminate ? I can bench test the lamps but obvs. don't want to blow them up.
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| 25th Sep 2024 11:32 am |
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darrind
Member Since: 04 Jul 2008
Location: In A World of My Own!
Posts: 2889
 
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Just a thought, does the car have tow electrics fitted? If so disconnect them (inside the rear Near Side - search on the forum for tow electrics to see where) as it could be some kind of issue with the towing electrics. Must stop buying shiny toys....
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| 25th Sep 2024 1:17 pm |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 13018
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Hardware wrote:BHave a look in left-hand cubby hole in the boot (not the one with the jack in it * ) and see if a trailer-lighting modification has been done/removed would be my first guess.
beat you to it, methinks !
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| 25th Sep 2024 8:00 pm |
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darrind
Member Since: 04 Jul 2008
Location: In A World of My Own!
Posts: 2889
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 Must stop buying shiny toys....
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| 26th Sep 2024 12:34 pm |
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Martin
Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18561
 
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Sundayjumper wrote:Possible dumb question - but do the brake / indicator LEDs expect +12V to illuminate ? I can bench test the lamps but obvs. don't want to blow them up.
Yes the lamps are 12V input 06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
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| 26th Sep 2024 12:47 pm |
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Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
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Excellent, thank you.
Last night I unplugged the connectors to the tow bar wiring (factory 12N + 12S, FWIW) and it made no difference.
Still not working this morning.
After a ~1hr drive today we're back to the driver's side working again !
I'll bench test the passenger lamp but I suspect it's fine. This is looking to me like a problem with the wiring and/or BCM.
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| 26th Sep 2024 12:58 pm |
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Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
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Update. We have all of the lights working but I'm not sure why
I tested both lamps off the car and they worked 100%.
Had a rummage in the wiring & reconnected the trailer sockets, next day the driver's side is out and the passenger side is working.
Yesterday I had a deeper rummage, still could not see any damage or anything suspicious, then yesterday evening they were all working ! So I think this narrows it down to the wiring in the nsr corner but the error code was for a short to ground and I really can't see any sign of that. Maybe I'll have to split the loom right out and re-wrap it.
Anyway, for now, I'm counting this as a win 
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| 30th Sep 2024 8:55 am |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 13018
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water getting in a joint ?
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| 30th Sep 2024 10:29 am |
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Sundayjumper
Member Since: 23 Sep 2024
Location: Berkshire
Posts: 104
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Maybe. There was no sign of anything but the car's hardly been used since the last MOT in December so I guess some damp might have crept in somewhere and it's gradually drying out now the car's getting used regularly.
I'm going to put it in for an MOT tomorrow while I'm on a roll  If it's damp related I don't want to be MOT-less and frantically trying to fix it at Christmas !
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| 30th Sep 2024 1:46 pm |
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Gary_P
Member Since: 03 May 2016
Location: Kent
Posts: 1664
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Can’t remember what those plugs are like that go into the back of the lights, but thought I’d share this. I had a problem with my indicators after my headlamps were replaced on my D4 (don’t ask). They blinked at double speed. I also had problems with a car’s brake lights a long time ago. Both issues were down to bad/corroded or slightly loose/not properly terminated connections of the wires going into the plugs (the ones that fit into the lights). An issue like that can make lights do funny things. So in a roundabout way, I’m saying it would be worth checking the wires into the plugs and possibly the connections on the back of the lights.
Good luck. Keep us updated. Gary
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Discovery 4 HSE 2016MY
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| 30th Sep 2024 3:47 pm |
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