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Lightweight lighting problems

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Hi there all,


I'm new to this forum, so just a quick hi, and a couple of questions-


I am currently helping to 'do-up' my friends 3 series Lightweight. Yesterday, I have managed to get the lights working, all of them except the fog lights, and the front headlights. The headlights work on the flasher on the indicator stalk, but will not stay on by selection.


Any ideas? I've checked all the fuses in the steering coloumn, but still cannot get the fog lights working.


Also, would anyone be able to show me a pic of the convoy light- I have the white diff pan, but there is no light.


Thanks very much,



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Tom as far as the fog lights go, trace back from:


Both fog lights & warning light are Red/Brown


where they join they are fed by Red


go to fog switch


which is fed by Blue/Red


going to C2 on fog relay


C1 is Blue/Red & joins with Blue/Red of LH & RH Dip headlight filaments


W1 Blue/Orange goes to IR switch


W2 is Earth (Obviously W=Windings C=Contacts)

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ISTR (and forget at MOT time) for FOG GUARD to work you need your headlamps on.


You need to sort your headlamps out first.


It would be better if you were able to state the VRN of your Lightweight , fog lamps appeared about HG (1980) and at first there was still a Infra-Red switch with Aux. (FV) relay. IIRC by KA the Infra-Red circuit was deleted.


If post KA then I would suspect the headlamp switch (copy ones are hopeless).


If prior to KA - then I would first suspect failure of the Infra-Red switch (famous for leaving you in the dark with only sidelights - another story).


You may best off to sign up for the ExMLRA Forum.


A gent (Disco 2000) there is doing many Lightweight versions with full trace colours, this is going to be a boon for future fault finding. I have been providing him with info. the drawing you specifically need may be the one I am having difficulty with - there may be a Fog relay as well.


This is where Disco 2000 (Dave) may have a for relay disconected :-









The above two diagrams and notes will explain how you can loose your headlamp lighting.




Something makes me think I have found such a relay laid amongs the wiring behind the dash on a Lightweight, don't know why they did not mount it above the service brake automatic check relay that was introduced.







Also :-




A few not so handy diagrams (late) with fog guard , non colour but key can be viewed on another page.

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I see what you mean about the switch, but its in the far left position (all lights) so I see no reason it will not work. I have ruled the Aux. Relay out, as the horn and hazzards work. Personally, I think it may be one of the snap connecters, that apparently are noutorious for collecting dirt. I am going to look into this at the weekend :)


Thanks for the help,




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That and Land Rover employing plumbers to do the job. The 101 wiring is a nightmare. I'd start by checking the six way switch, notorious **** for going wrong. You have my full and total sympathy. :coffee:

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Over 30 years ago I worked out a truth table for continuity check across the numbered terminals of these 6- way switches.


Just follow this with your AVO.


Swith @ 12 o'clock - OFF , always feed from terminal 1 to 6 (fuse in steering column fusebox)


Switch positions :-


Conv. - feed 1 to 2 (Convoy lamp)


S. Conv. - feed 1 to 2 and 4

(4 is front side lamps + panel instruments light switch)


T - feed 1 to 5 and 6 (5 is tail & 6 is feed to Aux. relay)


H.S.T. - feed 1 to 3 (3 is Headlamp) + 4 + 5 + 6


The above should also work good with all / most Military Land Rovers.







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Found out that in the end it was the IR lighting switch that had broken, and by simpily bypassing that the headlights are now working. I am now contemplating removing the switch and reparing it, but i am told not only is it useless, but it can blow the headlights.


Therefore the only reason i would want to repair it is becuase i'm picky like that and I like things to be original :nut:





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I have indeed taken the IR switch apart after I was left in the dark the night before when I was in the middle of Snowdonia. It was perfect inside , I had filed off the alloy rivet heads and re-secured with blobs of Araldite.


The problem on the IR switch is next to nothing because it has always been the same problem I have subsequently found.

The contact rivet heads on the rear have small flat washers & they would originally be coated with tin or silver , dampness causes a bit of corrosion and it gives a very high resistance. To restore a good electrical contact - all you do is give the washers a light tap with a small hammer & terminal screwdriver - this restores good electrical contact again for several years.


Somewhere I have a link showing the internal circuit of the switch with contact numbers - it is then easy to do a resistance or bell check to confirm it is OK before re-fitting.

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