Hi,
My left and right side brake/stop lights are not working and they send a bulb failure warning to the instrument panel. The upper mounted brake light still works so this eliminates the brake pedal switch and any fuse as far as I can tell.

I thought my problem must have been a faulty lamp control module so I sourced a second hand version but still no brake lights. And yes, I have tested both bulbs!

Any suggestions? Thanks

 

the high mounted stop light is on totally different circuit to the tail light brake lights.
it is not connected to the lamp control module and runs off its own relay.
so the high mount working indicates that yes the brake switch is working correctly. but does not rule out all fuses
it confirms that fuse #14 on the RH heelboard (being the main taillight fuse) must be working but does not rule out *one other possible fuse.
check Fuse #6 in RH heelboard.
are you sure the lamp control module you purchased is infact working correctly?
as yes LCM would be the likely culprit IMO.
do all other lights work?
is it possible that the wire has come loose on the plug at the tail lights?
seems odd that both sides would be affected by this but you never know.....

 

Thanks for the reply. I did check one of the fuses on in the RH heelboard, must have been #14 because it also worked the high mounted stop light. But I haven't checked the other 2.
All other rear lights work, it's just a brake light issue. I can't be sure the replacement LCM works, the ebay listing said it was 'tested as working' but I can't be certain

 

i did make a mistake above and have edited.
fuse #6 in the RH heelboard is for the 2 rear stop lights.
what i mentioned as fuse 14 in the lh heelboard is actually the revers lights. i made an error when reading the wiring diagram

the high mount is seperated from the two rear most lights for redundancy so if something goes wrong it is unlikely to lose all brake lights as it bypasses the lamp control module.
see attached images

 

There was a design change in 95 or 96 after VIN # 746613 which has 1 or 2 lamp control modules , the later version using only 1 in the trunk

The 2 light control modules ( one being the replacement ) between years may not be interchangeable

See page 112

jagxj1996.pdf (jagrepair.com)

 

I could be wrong, but i am pretty sure that aussie models all all came with only 1 lcm
mine is early 95 740464
and runs only one LXF2245AA

 

From what I have gathered there are 2 up front left and right under the bonnet

Mine does not have these

VIN # 755xxx

 

will check all when i get a chance but i am pretty sure that the combined lamp module in mine is on all aussie models.
will double check when i get home but i am pretty sure i looked at it all before in one of my posts.



it just seems like a topic i recall discussing before.
I could be mistaken tho

 

Ok all sorted. Major stuff up on my part, turns out both bulbs had died but because I had nothing to reference off I thought the stop light bulbs were the fog light bulbs. I'd forgotten the stop lights were actually a double filament bulb shared with a tail light. So once I replaced them both it's all good

And now I have a spare LCM...

 

ok, so you have the same LCM that my car has, which is the combined one.
so,
1 - brake switch - tested working as high mount works.
2 - rh heel board fuse 14 (lcm fuse) - tested working.
3 - rh heel board fuse 6 (tail light fues) tested working.
4 - tail lights correctly grounded (all lights share common ground wire)

the rear fog light is not the same globe as the stop light.
the stop light globe also has a tail (park) light but the fog light is seperate.
SEE ATTACHED IMAGES

maybe you checked the wrong globes before?
check the tail/brake lights and and make sure the large filament (brake light) is all good.
maybe just change them anyway as if the filament is slightly broken it may appear still good.
so do you have a multimeter/continuity tester?
i would first start by testing the sockets to ensure they are getting power when the brake is pressed.
does the small filament in the stop light globe (park light) come on with the park lights?

i suggest changing fuse #6 in the right hand heel board anyways as sometimes they can visually appear good but still be broken.
next step would be check the connections on the plugs for loose wires.
NY (brown yellow) going into the lamp control module (blue plug)
and then GO (green orange) and GU (green blue) coming out of the LCM (white plug)

tail lights on

fog light on (tail lights need to be on for fog light to activate)

brake light on only

 

Parker,
this is what i had previously discovered when working on my car.
the VIN which the cars came with the updated single LCM is much earlier. 739427.
so i remeber the conversation but forgot the exact details.

https://www.jaguarforums.com/forum/x...tem-257418/#15

 

Thanks, I realised my error and edited my post but you must have already been replying to it.

Because by co-incidence both bulbs were out I did get confused and thought the fog bulbs were the stop bulbs

So apologies for wasting everyone's time, at least I know a bit more about how the system works now..

 

no problemo.
always happy to help share the knowledge i have.
and when i don't have the knowldege i do enjoy educating myself to help other also.
especially with electrical stuff.

also see you are in aus... where abouts?

 

I'm regional QLD near Bundaberg. Not many Jags around here, especially anything a bit older