XJ40 headlights/sidelights - totally confused HELP PLEASE!
Discussion
Right - now I'm very confused and need advice.
I had a problem with my headlights & sidelights - XJ40 square headlamp model.
On sidelight setting, the sidelights in bumper come on OK and the driver's side headlamp glows dimly also - can anyone confirm that that is supposed to happen? The passenger sidelight however does not glow at all. On normal headlight and full beam settings both headlights work OK.
So, I have bought 2 2nd hand dim/dip control modules off Ebay and have just changed the passenger side one 1/2 hour ago.
Now the confusing bit - when I fitted the replacement passenger side module and turned ligths on to sidelight setting NEITHR the passenger or driver's side headlamp came on at all, just the actual sidelights in the bumper. How could changing the module on one side affect the other?
Next - I replaced the complete driver's side headlamp assembly, because the glass was cracked anyway - and now we are back to they way it was at the start i.e. driver's side glows dimly along with the sidelights but still nothing from the passenger side?
What's going on?
I had a problem with my headlights & sidelights - XJ40 square headlamp model.
On sidelight setting, the sidelights in bumper come on OK and the driver's side headlamp glows dimly also - can anyone confirm that that is supposed to happen? The passenger sidelight however does not glow at all. On normal headlight and full beam settings both headlights work OK.
So, I have bought 2 2nd hand dim/dip control modules off Ebay and have just changed the passenger side one 1/2 hour ago.
Now the confusing bit - when I fitted the replacement passenger side module and turned ligths on to sidelight setting NEITHR the passenger or driver's side headlamp came on at all, just the actual sidelights in the bumper. How could changing the module on one side affect the other?
Next - I replaced the complete driver's side headlamp assembly, because the glass was cracked anyway - and now we are back to they way it was at the start i.e. driver's side glows dimly along with the sidelights but still nothing from the passenger side?
What's going on?
An update:
I have now replaced the whole passenger side headlight as well - AND tried 3 different control modules, in addition to the original one - and also tried swapping the old & new headlamp with each 'new' module - and I'm still no further on. The passenger side headlamp still does not glow when sidelights are on but the driver's side one does.
Presumably then the problem must be soemthing else? Or could I have got 4 faulty control modules? Surely not?
I have now replaced the whole passenger side headlight as well - AND tried 3 different control modules, in addition to the original one - and also tried swapping the old & new headlamp with each 'new' module - and I'm still no further on. The passenger side headlamp still does not glow when sidelights are on but the driver's side one does.
Presumably then the problem must be soemthing else? Or could I have got 4 faulty control modules? Surely not?
Edited by mccrackenj on Monday 14th January 12:51
My XJ40 has the 4 headlight set-up and on that, when sidelights are switched on, I have both LH & RH sidelights in the bumper on and both outer headlights showing a dull glow - the so-called Dim-Dip arrangement.
It does seem odd that in swopping the LH module, the RH side is affected. Assuming that the control boxes are the same part number each side, I suggest doing a swop to see if the fault moves with it. It is possible that you have some iffy earth points or plug connectors with dirty connections!
I personally have had no problems with the control boxes on my XJ40 but I know they can be troublesome. They suffer from dry joints on the circuit boards. It is possible then to have them all faulty - and displaying different symptoms! The other point is if they are exactly the correct ones for your particular car. They do differ and not just for 2 or 4 headlights!
Unless anyone else can help, I think you will have to get replacement part that has either been tested and warrented as functional, a re-conditioned unit or a new one. Try Eurojag first, SNG Barratt second. I'm afraid that I would not try to source these notoriously troublesome units from dubious sources.
Hope this helps. Good luck
It does seem odd that in swopping the LH module, the RH side is affected. Assuming that the control boxes are the same part number each side, I suggest doing a swop to see if the fault moves with it. It is possible that you have some iffy earth points or plug connectors with dirty connections!
I personally have had no problems with the control boxes on my XJ40 but I know they can be troublesome. They suffer from dry joints on the circuit boards. It is possible then to have them all faulty - and displaying different symptoms! The other point is if they are exactly the correct ones for your particular car. They do differ and not just for 2 or 4 headlights!
Unless anyone else can help, I think you will have to get replacement part that has either been tested and warrented as functional, a re-conditioned unit or a new one. Try Eurojag first, SNG Barratt second. I'm afraid that I would not try to source these notoriously troublesome units from dubious sources.
Hope this helps. Good luck
Thanks Jaguarnut.
At least you've confirmed that the main headlight is supposed to glow slightly. What is the point of that I wonder? Why not a proper sidelight and a conventional headlight arrangement, instead of all this stupid faffing around with control modules! AAGGHH!
All 3 2nd-hand modules are def. the same part no. as the 2 already on the car, DBC 3271. I didn't want to get a new unit as the only new ones I've found were £125+ and even 2nd hand reconditioned are around £60 so I thought it was worth experimenting with some 2nd hand items off Ebay 1st.
As you suggest, there's nothing for it but to swap over the driver's side as another test. I'll do that when all the cuts and grazes on my hands have healed up. There not much room in there for swapping electrical connections and there's plenty of metal edges and sharp ends of plastic cable ties etc!
Thanks
At least you've confirmed that the main headlight is supposed to glow slightly. What is the point of that I wonder? Why not a proper sidelight and a conventional headlight arrangement, instead of all this stupid faffing around with control modules! AAGGHH!
All 3 2nd-hand modules are def. the same part no. as the 2 already on the car, DBC 3271. I didn't want to get a new unit as the only new ones I've found were £125+ and even 2nd hand reconditioned are around £60 so I thought it was worth experimenting with some 2nd hand items off Ebay 1st.
As you suggest, there's nothing for it but to swap over the driver's side as another test. I'll do that when all the cuts and grazes on my hands have healed up. There not much room in there for swapping electrical connections and there's plenty of metal edges and sharp ends of plastic cable ties etc!
Thanks
Ah....stuff from e bay.
Dim Dip control modules are a common known problem on XJ40s
Are you sure you have not bought faulty replacements that some theiving pikey has put on hoping to make a few quid from faulty parts that should have gone in the bin?
Try Euro Jag if you need s/h spares for Jaguars
Dim Dip control modules are a common known problem on XJ40s
Are you sure you have not bought faulty replacements that some theiving pikey has put on hoping to make a few quid from faulty parts that should have gone in the bin?
Try Euro Jag if you need s/h spares for Jaguars
Agree with last post, about checking that you have a good control module. Like I posted before, it is possible to take these apart, and solder up the dry joints inside, ( if you can find someone who knows a bit about them, or circuit boards in general.) If the module is ok, I would be looking at a wiring diagram, with a view to a broken/ corroded wire down to the module. Sometimes down in the loom behind the module where it curls up and down, somethimes further up on the inner wing.
Thanks melhook (and everyone else).
I'm no use with electrics, I'm afraid. I'll get the grille and both headlights light out this Sat and have a play around, swapping all 3 replacement modules with the one that does work, on the driver's side. If any of the replacement modules works OK on the driver's side then it's obviously something else that's at fault - so it'll be off to a mechanic/auto electrician.
Drove it to work today and, lighting issues apart, I'm really starting to like it, so quiet and relaxed.
I'm no use with electrics, I'm afraid. I'll get the grille and both headlights light out this Sat and have a play around, swapping all 3 replacement modules with the one that does work, on the driver's side. If any of the replacement modules works OK on the driver's side then it's obviously something else that's at fault - so it'll be off to a mechanic/auto electrician.
Drove it to work today and, lighting issues apart, I'm really starting to like it, so quiet and relaxed.
I think you really need to understand where the fault actually is and to do that you need to understand what is working correctly. You should have a sidelight and an outer headlight glowing dimmly on each side with only sidelights switched on.
I think you said that the RH side works like this. This is correct. Next, remove the LH module completely. Try the sidelights and check nothing has changed on the RH side. Switch off, remove RH module and connect on LH side. Switch on sidelights. LH side should now work perfectly. If it does, you certainly have a problem with the original LH module or an intermittent problem with wires or connectors. Remove module and replace back on RH side, ensuring all is well afterwards. You then know that the LH is the issue. Sad to say I would expect all your replacements to be suspicious.
If however having moved the RH module to the LHS and the fault re-occurs, you have an issue with wiring and/or earth points on the LHS. Confirm by moving it back to the RH side and checking all is well.
By now you should have a known baseline, in that you have confirmed that the RH side works perfectly. You should have confirmed that when replacing LHS with RHS module all is well. Result, known dodgy LHS module, likely including your spares. OR you will have identified (if RH module now appears faulty on LHS) you have a wiring problem outside of the modules. (confirm when retesting RH module on RHS!) If you have understood this and the fault resolutely remains on the LHS, you quickest/cheapest route to happyness is to purchase a tested replacement through Eurojag which then should cure your problem. However, if you discover other strange goings-on, then it needs more specialist investigation in view of your comments about electrics! I would personnally not bother with an 'unknown' auto-electrician unless you know they have plenty of Jaguar experience. I fell into that trap - and with a known XJ40 problem hat he could not even find! Better that you find a reputable Jaguar specialist in your area who is conversant with XJ40 peculiarities! This will be your other cheapest.quickest route to resolution!!! Good Luck.
I think you said that the RH side works like this. This is correct. Next, remove the LH module completely. Try the sidelights and check nothing has changed on the RH side. Switch off, remove RH module and connect on LH side. Switch on sidelights. LH side should now work perfectly. If it does, you certainly have a problem with the original LH module or an intermittent problem with wires or connectors. Remove module and replace back on RH side, ensuring all is well afterwards. You then know that the LH is the issue. Sad to say I would expect all your replacements to be suspicious.
If however having moved the RH module to the LHS and the fault re-occurs, you have an issue with wiring and/or earth points on the LHS. Confirm by moving it back to the RH side and checking all is well.
By now you should have a known baseline, in that you have confirmed that the RH side works perfectly. You should have confirmed that when replacing LHS with RHS module all is well. Result, known dodgy LHS module, likely including your spares. OR you will have identified (if RH module now appears faulty on LHS) you have a wiring problem outside of the modules. (confirm when retesting RH module on RHS!) If you have understood this and the fault resolutely remains on the LHS, you quickest/cheapest route to happyness is to purchase a tested replacement through Eurojag which then should cure your problem. However, if you discover other strange goings-on, then it needs more specialist investigation in view of your comments about electrics! I would personnally not bother with an 'unknown' auto-electrician unless you know they have plenty of Jaguar experience. I fell into that trap - and with a known XJ40 problem hat he could not even find! Better that you find a reputable Jaguar specialist in your area who is conversant with XJ40 peculiarities! This will be your other cheapest.quickest route to resolution!!! Good Luck.
Thanks Jaguarnut for taking the time and trouble to type all of that.
I will be swapping RHS & LHS modules back and forth this weekend and then I'll know whether it's the modules or not. If not, then I've already made sure that the earth is good on the faulty side so next step will be to find someone locally who knows their XJ40s.
I'd better not do what I did last Sat though - left the passgr side headlight 'resting' on the bumper while switching lights on/off again - then 'crash', 'tinkle'. Another new headlight unit required! What a prat!
I will be swapping RHS & LHS modules back and forth this weekend and then I'll know whether it's the modules or not. If not, then I've already made sure that the earth is good on the faulty side so next step will be to find someone locally who knows their XJ40s.
I'd better not do what I did last Sat though - left the passgr side headlight 'resting' on the bumper while switching lights on/off again - then 'crash', 'tinkle'. Another new headlight unit required! What a prat!
Oops! Not sure on the single headlight models, but on my 4 headlight version,I can access the rear of the headlights from under the bonnet. I just have to move aside a peice of rubber sheet.
I think that your best bet is to totally disconnect the left hand side headlight and module and then ensure the RH is perfect. You can simply work from there using logic. Any understanding of electrics or not can then really be ignored.
As with most XJ40's, if you have got a good one, then they are a very competent and highly enjoyable beast. They are worth sorting out the foibles! It is a shame that they are so underrated. I read an article wrote by someone far more knoledgable on these cars which stated that "..they benefit from intelligent, hands-on repair to keep them on-song". I could not agree more and could give you many instances with mine which demonstrate that.
Keep plugging (!) away. It is worth it.
I think that your best bet is to totally disconnect the left hand side headlight and module and then ensure the RH is perfect. You can simply work from there using logic. Any understanding of electrics or not can then really be ignored.
As with most XJ40's, if you have got a good one, then they are a very competent and highly enjoyable beast. They are worth sorting out the foibles! It is a shame that they are so underrated. I read an article wrote by someone far more knoledgable on these cars which stated that "..they benefit from intelligent, hands-on repair to keep them on-song". I could not agree more and could give you many instances with mine which demonstrate that.
Keep plugging (!) away. It is worth it.
It is possible to access the modules etc from under the bonnet, but space is limited - there's not much room for disconnecting & reconnecting the modules etc. Getting the grille out and removing the headlamp units doesn't take long, especially as everything was out & back in only last week so all the nuts etc are nice & free, and it gives a lot more room to play with. I have 2 spare bulbs so I'll be able to swap the modules around and test without disconnecting & reconnecting the whole headlight assemblies over & over again. Pity I didn't do that last Saturday, I would still have a spare one!
I'm determined to get this sorted though - because apart from this and some minor rust (which can be sorted easily if it's tackled now) and a few other frankly trivial things, the car is in superb condition and runs beautifully. All it needs apart from the above is a pair of tyres and a thorough service / change of fluids & filters.
I'm determined to get this sorted though - because apart from this and some minor rust (which can be sorted easily if it's tackled now) and a few other frankly trivial things, the car is in superb condition and runs beautifully. All it needs apart from the above is a pair of tyres and a thorough service / change of fluids & filters.
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