Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Strange headlight operation - xenons
Evening all,
I am having very strange problem with one of my headlights which I had put down to a failing ballast. On replacing the ballast this evening, the problem persists, I have even swapped the two headlight ballasts and the problem persists in the original light, hence ruling out the ballast.
I have also changed bulbs in recent weeks, so that too is ruled out.
The problem is that one headlight beam (passenger side) shuts off after between 36 and 38 seconds of operation. It will operate again straight away if I turn on and off the light, again only for 26 odd seconds. As above, I swapped ballasts from one side to the other and the problem remained in the passenger side. I checked the length of time set for Follow Me Homes lights and that is 30 seconds.
It is hardly a relay as that would send power to both surely? Anything else, could it be a rogue programming error - to note I have not updated anything or changed anything (except updating software on AC system, but that predates the problem).
Any thoughts or suggestions as to what I should try next to identify problem?
Thanks and regards
Dave
14th Aug 2014 9:46 pm
DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Anyone have any thoughts? Where would I start, I have read that there is some central junction box that sends power out to the 4 main lights (2 dip, 2 high beams). What controls this? Could it be at fault?
Kinda getting worried now that I may end up at the dealer . . .
15th Aug 2014 5:19 pm
DSL Keeper of the wheelie bin
Member Since: 11 May 2006
Location: Off again! :-)
Posts: 72986
Anybody close to you so that you could bung their lights in to rule in or out the light units?
15th Aug 2014 5:27 pm
Allan_T
Member Since: 10 Sep 2012
Location: Northampton
Posts: 1034
... or swap your lamp units to the opposite side, obviously they won't physically fit but the connectors will. See if the problem still exists on the passenger side using the drivers side lamp unit.GAP IID Pro Multi Vehicle Defender L316 2007-2015 - Discovery 3 - Discovery 4 - Discovery Sport L550 - Freelander 2 - Range Rover Evoque L538 - Range Rover L322 - Range Rover L405 - Range Rover Sport L320 - Range Rover Sport L494 Electrical Fault Diagnostics
tried moving the connector around to see if there are loose wires or bad connectors ?
but be very careful of the internal ones as high voltages !BREXIT - done properly.
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15th Aug 2014 8:08 pm
DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Hi guys thanks for suggestions, I will try swapping headlights into other connectors but worried that it is not that simple . . . I have swapped the ballasts and bulbs and still they cut out at the 'magical' 36 seconds.
As I say, I will try swapping the headlight units, but I fear it is the supply to headlight that is the problem - but only the xenon. . . the high beam, indicator, side light all function correctly. Also, when on high beam, after the 36 seconds cutting out of the beam, it does not cancel the high beam on the other light.
Can anyone point me at the wiring diagram for the headlight operation please and thanks
Regards
Dave
15th Aug 2014 11:12 pm
Allan_T
Member Since: 10 Sep 2012
Location: Northampton
Posts: 1034
GAP IID Pro Multi Vehicle Defender L316 2007-2015 - Discovery 3 - Discovery 4 - Discovery Sport L550 - Freelander 2 - Range Rover Evoque L538 - Range Rover L322 - Range Rover L405 - Range Rover Sport L320 - Range Rover Sport L494 Electrical Fault Diagnostics
16th Aug 2014 9:18 am
DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Thanks for that
Had a look at the main and engine bay fuseboxes and cannot find the Relays for the headlights, according to the wiring diagram here should be two of them. I want to swap them with each other to see if that is the root of my problem.
Can anyone confirm where they are?
16th Aug 2014 12:58 pm
AN
Member Since: 26 Jul 2005
Location: Hungary
Posts: 327
I just looked the wiring, bad news they are not a relays, they are FETs:
"Low Beam
When the lighting control switch is turned to the headlamp position, current flows across the switch (C0041) to the CJB (C0580) on a Y wire. With the steering column multi -function switch in the low beam position, the CJB provides a signal feed to the LH low beam FET, and the RH low beam FET. Both are located in the CJB and are provided a ground (C0585) on a B wire. The LH low beam FET (C0583) provides a feed to the LH low beam bulb (C0009) on a UK wire. The RH low beam FET (C0583) provides a feed to the RH low beam bulb (C0011) on a UO wire. Both are provided grounds on B wires.
Main Beam
When the lighting control switch is turned to the headlamp position, current flows across the switch(C0041) to the CJB (C0580) on a Y wire. With the steering column multi -function switch in the main beam position, the CJB provides a signal feed to the LH main beam FET, and the RH main beam FET. Both are located in the CJB and are provided a ground (C0585) on a B wire. The LH main beam FET (C0583) provides a feed to the LH main beam bulb (C0009) on a US wire. The RH main beam FET (C0583) provides a feed to the RH main beam bulb (C0011) on a UB wire. Both are provided grounds on B wires."
FET is build in in CJB, cannot be replaced. Maybe there is a small short circuit on the wire thus the FET will overheat and switch off (this is how it should work, like a fuse/switch). When it cools down after you switched off the car. It works a while and overheats again. I would investigate the wiring from CJB to the light.LR D3 S Black, Auto TDV6
16th Aug 2014 4:16 pm
albal
Member Since: 31 Jul 2011
Location: Southampton
Posts: 592
The design uses excess heat in the FET to shutdown the circuit. At 45 or so seconds it's only a little extra load. If you swap the bulbs and it moves to the other side then it's the bulb. If it remains then you have a weak short somewhere - possibly debris in the connector.
edit: ooops AN said all of that...
16th Aug 2014 4:37 pm
DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Thanks for the above guys,
Pity it cannot be something simple like swapping a relay or fuse.
I suppose first thing is to swap the headlights and see if there is an issue at that end. After that, I am fairly blind as I would have no idea where to follow the cabling back from the light.
Apologies for ignorance, but is the CJB some sort of black box that is visible or is it part of the fuse board behind the glove box. I do not even know what I am looking for!
Do you reckon that this is something a dealer could trace and sort easily or not. Even worse, could it be a failure of the CJB and if so, is that a huge bill looming?
16th Aug 2014 9:06 pm
DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Oops double post
16th Aug 2014 9:50 pm
albal
Member Since: 31 Jul 2011
Location: Southampton
Posts: 592
Central Junction Box (CJB), Central Fuse Board or Body Control Module (BCM) - all one and the same.
Can be replaced but it has to be ordered for the car (it's by VIN) and you'll need to re-program all your keys again.
FET's are generally hardy so I would go over your wiring down to the bulbs very carefully.
If it was the FET in theory you could solder another item in it's place but practically the BCM is probably built in such a way that getting to it would destroy the BCM or it won't go back together again.
As you are running Xenon you can't just put relays in but one other option would be to slave a secondary FET off the first one (as in a whole extra board design - I'm not saying you could do that with one FET component).
I'd use a decent DVM and resistance check your loom at various points. Personally I'd think that is easier than removing the lights and then swapping them back.
17th Aug 2014 12:18 am
DaveJLBI
Member Since: 07 Mar 2014
Location: Clare
Posts: 678
Head hung in shame. . . . .
There may be a simpler answer to this problem.
I swapped the headlights from each side and lo and behold, the problem swapped sides, thus proving the problem is in the headlight. From above, I had swapped the ballasts as I initially was sure that was the problem but never thought to swap the bulbs (as the ones in it were new and I never thought to question new Osram CBIs).
Anyways, swapped out the bulb on the side that was failing with the old bulb (kept in the vehicle just in case) and it worked without failing. Gonna swap the bulbs to the other side to confirm that this is point of failure and then contact the supplier.
Hopefully this may turn into an easy solution . . . .
I've been having a similar issue with my headlights, although at a much longer interval, 1/2 hr or so before the light will go out.
I swapped the bulbs (just the bulbs, not the whole headlight assembly) from one side to the other and a few days later, the other side went out. So, off to see about new bulbs tomorrow.
Or I may just order some Night Breaker Unlimiteds and wait for them to arrive..
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