A 1996 XJ12. just as it says, on Low, the Pax side light stays stays dark but when you go to High or Bright (pick your term) all four lights come on. Need to go check to see if the parking lights work. If it was a fuse I would expect that the light would not come on at all? Stalk? Troubling shooting thoughts?
[quote=“Bimbi1, post:1, topic:350619, full:true”]
A 1996 XJ12. just as it says, on Low, the Pax side light stays stays dark but when you go to High or Bright (pick your term) all four lights come on. [/quote]
Might be as simple as the ‘low side’ filament of the Pax side bulb is burned out
Cheers
DD
Hmm, I had assumed with four headlight fixtures that they were all single filament bulbs. Been a while since I changed them and I can’t find the used bulbs right off that were good but I don’t recall one looking as if it had two filaments. I think the low beam housing has a second small bulb for the parking lights but I’d better take a another look.
[quote=“Doug_Dwyer4, post:2, topic:350619”]A 1996 XJ12. just as it says, on Low, the Pax side light stays stays dark but when you go to High or Bright (pick your term) all four lights come on.
[/quote]
I’m not sure what Pax means,both the RHS & LHS LCM’s have individual switched feeds for the 3 bulbs so the fault is non-logical but has to be either the LCM at fault or possibly a PO has frigged the wiring.
I don’t kow if the LCMs can be swopped over but if they can I would do so and check if the fault moves across too. But AFAIK the bulbs are all single filament.
Single filament? Yes, possibly. If I remembered incorrectly it won’t have been the first time! 
Cheers
DD
Oh come on Neil, everyone knows it’s Latin for passenger:-)
Gary,
Or in your case “Fares”? 
Unlike you Gary I didn’t attend a Public School being a Grammar boy so I had to study Welsh, French and German not Latin!
I thought X300/308 were a pair of single filament high beams and a pair of twin filament high/low lamps -the difference being positioning and which of tge lamps housed the small pilot bulb?
It has been a while but I’m sure there were twin filaments involved somewhere.
Peter, it is a little confusing as the some images DBC11313 appear to have two filaments, but the Electrical Guide Fig. 09.2 only shows a single switched feed to the Main, Dip & Pilot bulb on each Headlight unit.
Also as recorded on Jim Butterworth’s site: " Also the X300 has the sidelight in the outer dip beam lamp; the X308 moves it to the inner head beam lamp." I have fitted X308 units on my X300 and all the 4 bulbs are Osram Nightbreaker H1.
So Bimbi’s fault is a strange one, particularly as I don’t know the car’s history.
When I fitted V8 grille, bumpers and lamps to my 94 Daimler, I rewired/moved them so the pilot bulbs were on at the same time as the dip beam outers - giving four lit lamps on dip, which looked nicer than only two lamps lit around town.
That’s the configuration that is basically on both the X300 & X308 all lamps lit.
Actually it turned out to be my first guess…not the dipped beam on the passenger (North American) or right side but of course it was the parking light bulb. Had a spare bulb in the bulb kit in our older XJ40 so it turned out to be much easier than I thought.
Pretty sure all the larger bulbs are single filament and the outer housing has the dipped beam as well as the parking or sidelight.
Since I wouldn’t mind more light I am still giving thought to doing the X308 conversion or at least better bulbs. The last bulbs we put in are “okay” when new but they seem to dim with age at a not so good rate.
Years as a travel agent and spouse being a pilot had me thinking “pax” was a common term for “passenger”…better than the terms used at some airlines for the people that pay the bills.