Hi,

2001 Sovereign.

Just encountered a problem that I cannot solve. My right breaklight
no longer works. I've checked all items from the lamp right through
to the fuse and there is no power. There is a relay in the fusebox
in the boot but I've no way of testing it. I have been told by
another Jag owner that he has the same problem and cannot get it
fixed unless he tries the Jag dealer who has told him it may be a
faulty ''electronic control'' which could be very expensive.
I'm tempted to cut the wire from the relay to the faulty brake
light and then ''hotwire'' to the light from the working left brake
light.

Any help would be appreciated,

Dave

 

Dave:
I do not know what you mean that you checked through "all items" since there is no direct connection from the fuse to the brakelight. The brakelights are controlled by the security and locking module which is located immediately rear of the battery. The electronic device inside this module that controls the lamps is called a smart silicon switch, and there was a fellow willing to change the part for a nominal (or less, as I recall) fee. The archives would yield his info - look under brake light stuck on, since that is the more common failure mode for the module. Note the more common spelling of the word brake.

In fact, your problem may not be the actual module and might be a frayed wire. i do not remember if the brake light wiring goes through the harnes at the right side hingd, but there is a common fault with this harness getting skinned up and causing problems in the trunk area.

If you connect both bulbs to one output without an interposing relay, you will almost certainly burn up the output device on the other circuit.

Good luck and report back your results!

 

Hi Ross,

I meant I checked the fuse, lamp and harness. The relay controlling the Brakelights I suspected would be large enough for 2 lamps of 15w which is less than 3amps, so bearing in mind that the Guardia Civil Traffico here in Tenerife are S**t hot at the moment, I took the risk of looping both lights off the one supply after cutting the supply cable to the faulty unit to stop any backfeed into any electronics. All seems to work OK other than when applying the Brakes I get a fault message "Check rear lights" which I can live with until I get more info to do a "Proper" job. I asked a friend who works for Jaguar in England and he says a new security module is £276.00 +VAT & fitting!! Rather OTT for a faulty Brakelight.

 

Hi Again Ross,

Just had a further thought, is the rear window break light direct from general electrics or does this also go via the security unit?

Dave

 

Check the ground wire on that brake light module. This link is to a oneline for you’re my car http://www.jagrepair.com/images/Auto.../jagxj2001.pdf

 

Hi Gus,

The ground wire was OK. I have the Light working now, looped from the other breaklight. I would like to think that this is only temporary and that I can find a permanent solution without having to resort to a new security consul.

Regards,

Dave

 

Dave:
The center light does indeed get fed from another source. The individual circuiots are not fed with a relay, but rather the solid state device I mentioned, which gets pretty hot wih two lamps connected- I know because I tried your approach myself and I felt it after I took the case apart. However, your module is bad anyway, so I suppose you have little to lose, unless you have an electronic tech friend to help fix the old one. And then you can put 2 SSS chips in with about the same trouble!
Good Luck.

 

Thanks Ross,

Luckily the breaklights are on only intermittantly so hopefully it wont heat up too much. I have also fitted another lamp from the wire I cut which has now removed the "Check rear lights" message.
As I live in Tenerife where Jags are few & far between and only 1 registered dealer I don't think I've much hope in finding someone who has the expertise to repair the unit. I will have to try to find someone in the UK who could oerhaps get me a second hand one.

Regards,

Dave

 

The suggestion to find someone to repair it was not for a Jaguar guy as much as an electronics guy. There are probably not as many of them on Tenerife as some other places, either , I suppose. If you have to go back and fix it, then post back and I will look up the part numbers for the "high side smart silicon switch" for you.

 

Many thanks for the offer Ross but I'm at a bit of a loss as to what the "high side smart silicon switch" is. I'm assuming that is the unit which has gone faulty. Do you need some serial numbers from the unit? also is it the unit which is under the fuse unit in the boot or is it under the passenger seat somewhere as I keep hearing clicking sounds when the car "self tests". If I can locate a unit on the internet/ebay etc. what do I need to do to the unit to have it "bond" with my car. I read in another post that if you change the unit then all keys etc will need to be changed/programmed as well. As I said previously it seems to be a bit of overkill by Jaguar to have to replace so many things and at a great cost just because of a stop light.

Regards,

Dave

 

Dave:
The security module is in the trunk rearward from the battery, under the fuse panel. the part is a little $3.00 compnent soldered onto the circuit board inside the module. The module must be sawed apart at the glue line to get to the board, so it is not a good first electronic repair project!
If you fix the old one, you do not have to worry about reprogramig.
As to the complexity, the security module runs the brakes because the car alarm flashed the brake lights to show alarm activation and for alarm sounding.
So, with features comes complexity! evenmost home appliances have microcircuits in their control systems and electronic circuits are, in general, much more reliable than electromechanical relays and such. But, as you say, when they go, it gets expensive and requires specialized repai techniqies. Good luck with it and Merry Christmas.

 

Many Thanks for all your help Ross.
Merry Xmas to you too
and all the best for you and your family for 2011.

Kind Regards,

Dave

 

I have a 2001 XJ8 3.2 Executive. The right hand (starboard) stop light was not working and there was no electrical power to the bulb holder. I followed the advice from an earlier forum, so I am merely expanding on this.

The fault was in the Security and Locking Module, which is under the fuse box adjacent to the spare wheel in the boot.

You can easily remove this unit and open it up. Looking at the PCB with the black connector board facing down, there are three switches (relays) together on the right hand side.
The relay for the right hand or starboard stop light is the one on the left nearest the two larger relays. The part number on this in my car was 71042SE, but I believe that earlier modules have the part number BTS409L1.
I could not source a 71042SE and I replaced the faulty switch with a BTS409L1 and this cured the fault.
I obtained the switch from LittleDiode.com and you have to order a “BTS409L1 SMD”. SMD means surface mounted device. This cost £21 including P and P delivered with first class recorded post. Their service was great.
I tried to de-solder the switch with my existing solder iron to no avail. I went to Maplins and bought an Antex XS 25 watt iron which did the trick. I also bought a fine tip for the delicate work. This added some £30 to the bill, so if you would not consider this a good investment, then you may wish to get a TV technician to do the job.
The base of the switch is actually soldered onto the PCB and I used a bigger soldering iron to de-solder it.
On replacing the switch, I put a couple of spots of solder on the base of the switch. I then soldered the connections first and then pushed down on the switch whilst I held the soldering iron against the metal part of the switch. The solder soon melted, but the switch got a bit hot. I was concerned that this would damage the switch, but it seemed to be OK.
I have included a photo of the PCB.
I hope that this is of some help.

 

Welcome, thanks for your image , this is very informative post for a very 1st message ,I appreciate that

 

nice. I'm trying to solve this myself as we speak.

 

Further to my last post, I notice that you can now buy the BTS409L1 SMD on E Bay from Little Diode for £7.50 including P and P delivered to the UK(quite a bit cheaper).

They will even mail it to Colonials.

Regards

Brian