Whilst out last night, I got a "CHECK REAR LIGHTS" warning every time I hit the brake pedal. When I got home I left the engine running and switched all the exterior lights off. The stop lights remained on?? I then switched off the engine and removed the keys, lights still on?? Had to resort to disconnecting the plugs to each rear light.

The High Mounted top Light, works as normal. The only reference I have found in the PDF manual is that relay 5 in the boot fuse box is for the High Mounted Stop Light/ Trailer Stop lights.

I would suspect a stuck relay for the other brake lights, but can't find a reference to one!!!!!

Anyone with any ideas??? Thanks Bill W.

 

The rear stop lights run through the security locking module so they're controlled via that part. There's a fairly common problem with this module, if you search this forum you'll find info on it.

It's located under the trunk fuse box, maybe water ingress so first off is to get at it and clean connections.

 

Thanks Sean B I will have a look.


Any Ideas why the High Level Brake light works via a relay in the Boot Fuse Box, and the main ones use the SLM?
My theory was that the High level was added in the x308 that used the x300 SLM, so they just added a relay. Any reason for the Brake lights to go through the SLM rather than a relay? Bill W.

 

High mount center stop lights started in 1985 (USA)

So all the x300's in the USA had them .. I think all the xj40's had them. Lots of cars use a relay for the center setup.

The control module for the lights is a known failure point .. annoying. Replacing it requires the correct part version.

 

Sean B,


Just took the SLM out and like the rest of the boot it is absolutely clean and dry...


Heard somewhere about running them from the same relay as the High level light. As it is designed for the stop lights on a trailer It could cope. What worries me would be what errors would be generated by them not using the SLM as a monitoring medium... Might have to bite the bullet and have a look on Fleabay!! The LNG 2600JB is followed by /001 on the VCATS label, what does the /001 define??


Thanks


Bill.

 

Took SLM out and opened it up, one of the FET's has gone, so getting another from fleabay, should be here Wednesday. Will report back. Bill W.

 

I had problem with stop light, it was that chip in SLM to blame. Temporarily I wired tail lights to trailer light wire, ordered chip from mouser, replaced it, and rewired everything back. So far so good...

 

Please forgive my ignorance, but what is an FET ?

TIA

 

Jimmy. I seem to remember that A F.E.T. is a Field Effect Transistor, Used for switching relatively high currents.


NJ2003XJ8.
Which chip did you replace? I have a photo of what has blown in mine, and have attached a photo. There are 3 identical devices that I have assumed are FET's, the Left hand one in the pic is the one that has blown. I have ordered another SLM of the same part No but I assume I will have to sync the key fob to the new SLM.

 

Heliwilly, you got it right -

"The FET controls the flow of electrons (or electron holes) from the source to drain by affecting the size and shape of a "conductive channel" created and influenced by voltage (or lack of voltage) applied across the gate and source terminals."

I never was very good at electronics. ;^)

 

JimmyL,


I think that when you get into your seventies, your brain is filling up with so much new stuff, that a lot of the old stuff overflows like a waterfall and is lost. At least that is my excuse.
I was a Telephone Engineer all my working life. By the time I came to retire, All the systems were solid state and repairs were done by board changing.
Back to Jaguars. When I bought this one 6 weeks ago it had a few problems, but they were mechanical. The stop light problem only reared its head recently. I will replace the SLM, but what could have caused the problem in the first place?? Is this bad luck?
I know that it is a known problem, but has anyone come up with a definitive cause. I have seen nothing in any of the TSB's I have looked at. It would appear that it could possibly have been a short circuit that caused it. Was it water?? A faulty component??
Bill W

 

I haven't had this issue come up yet, so I am interested in the cure and the cause, if possible, for future reference. From your photo it almost looks like the solder melted away from the FET. As far as the years go, I'm not far behind, but we're all virtual kids on here. ;^)

 

I replaced chip next to relay ( thanks to DAWells23 for marking it with a dot in thread "Passenger side rear brake light not working, already replaced bulb "), that one is responsible for passenger side lamp. My little story is in thread "Passenger side stop light and back-up sensors problem ".


FET is supposed to be "electronic relay" with overload protection, but by the number of failures it looks like mechanical relays with fuses work much better.


One more thing - I was blaming my problem to the fact that bunch of wires that go into rear lamp assemblies are sitting against sharp metal edge waiting to get pinched by something heavy shifting in the trunk. I suggest you put a piece of plastic over that edge or put few layers of tape around wires.

 

From your picture it looks like chip got so hot that it melted solder, moved and got itself "re-soldered" so that connections are now messed-up causing break light to stay on. I would replace the chip and see if it works, much cheaper than new SLM with keys re-programming. You may need to replace both chips though as both of your lights are faulty.

 

NJ2003XJ8,


I actually removed the duff FET and placed it back in situ. I has a hole blown in it and the area around it has black molten "plastic" around it. I will heed your warning of the wiring round the tail lights.


Cheers Bill W.

 

Hi,
Replacement SLCM arrived this morning. Replaced the old one. Works fine. I just have to re-code the remote fobs. Any ideas on the best method to use. Thanks Bill W

 

https://www.jaguarforums.com/forum/x...ers-faq-33580/

 

Thanks for all the help. Both the remotes re-coded. I used the Hold the head light flasher, put ign in pos 1 method. Although I got the flashing LED I got no chirps or beeps, but the keys coded OK and are useable. I even locked the doors on the remote and opened them with the key to test the alarm. That worked OK. All I need now is a replacement FET and I will have a spare SLCM in case of a repeat.