We have a 98 XJ8, which, other than a transmission failure and some squeaky creaky behavior, has been a far better car than the 2001 BMW 7 Series.


However, out of the blue, a stranger tells me my break lights are not working. Sure enough, no brake lights on the truck of the car. The third brake light looks light it was trying to work, but a lot of the LEDs on the third eye have burned out.

Bulbs appear to be good.

I am sure this is not new, but I don't see a similar posting unless I am overlooking it.


Any thoughts?



John

 

Have a look at fuse #1 in the trunk fuse box- the one right to the rear of the battery. The brake lights are controlled by the Security and Locking Module (SCLM)in order to control them flashing when there is an alarm. There is a solid state component in there that is known to fail, but it has one per side, and it is unlikely you failed both. The high lamp is un from a different circuit.
While you are in the trunk, look at the wiring harness at the right side hinge are. Examine it carefully for fraying. I would not expect it to have your symptoms. but it is a known problem area.
If you have a 12 volt test probe ($5.00 or so at Harbor Freight), you can diagnose this completely, just check back.

 

All of sparkenzap's suggestions plus....
The brake light switch which is attached to the brake pedal is a known weak point and shouldbe replaced.
The high level or 'third' brake light does not have LED's, just ordinary 5w 'wedge' bulbs....4 or 5 of them ;o)

 

Second attempt at posting a follow up. I am no mechanic. I appreciate all sincere replies.

1. I am finding no fuses that are bad. Of course, I have yet to find any fuse labeled specifically for the brake-lights. Is there a particular fuse? Which fuse box is it located in?

2. If the "third" brake light still works, could it still be a bad switch?

3. Is there a module somewhere in this car for the brake-lights? I was told that there was not, but I seem to recall that a long time ago, we had a brake light issue and a module was the culprit.


Any answers to 1 or 2 would be great.


If anyone knows about question 3, can someone please tell me where this damn module is, what it looks like and where I can get a new one?


John
Clearwater, Florida

 

John:
I know I am not the most articulate writer, but what part of "#1 fuse in the trunk (boot) fuse block" do you not understand? And, THE SCLM is the "Security and Locking Module", located under the aforementioned fuse block.
Clearly we have a failure to communicate!
Anyway, check that stuff and get back. This is really easy to diagnose, if not repair.

 

Below is information from forum other thread on brake lights:
Comment:
The security locking control module controls brake lamps except the high mount lamp. The lamps are controlled independently from the SLCM for right and left so a problem with the module could cause one lamp to be out.

Thread weblink:
https://www.jaguarforums.com/forum/x...working-86245/

Here is a photo of the battery box access to the Security Locking Control Module (SLCM):

https://www.dropbox.com/s/7bxeol7dls...ss%20Photo.JPG

You have to remove the fusebox in the photo to gain access to the SLCM.

Jim Lombardi

 

I guess the problem is that I am (a) finding no bad fuses nor (b) am I finding any that are labled "#1". However, there is a chart of sorts identifying fuses for pretty much everything else.

I will look at and see what it takes to remove the fuse box as I suspect it is the module. I don't usually get luck with cheapo repairs--for me, a problem it never as simple as fuse it seems.

Thanks,


John

 

Ok, great. At least now I now where the culprit actually is. Any easy way to tell if it is bad?

 

g"Any easy way to tell if it is bad? "b


Yes, as I told you in the PM, you need to follow a procedure with a test lamp or meter, and follow the schematic. If you have experience following a schematic, one of us will send it to you. If not, we can walk through it with you. Do you have the test light? (Harbor Freight, $5.00).

I am sorry- I thought there were numbers on the fuse blocks. I am away from my computer with the documentation , but maybe Jim will copy the diagram that shows which fuses are which. It might be in the owners manual.

What we are goin to do with the test light is check the switch signal into the SCLM, then check that the SCLM has power and grounds, then we will test the SCLMs response to the input signal at the brake light outputs. Pretty simple actually, and then you will know fairly accurately what parts to go after.

And, BTW, I understand your frustration with a Jag-u-wah, but the simplest solution is many times the right one in diagnostics. Check "Occum's Razor" on Google.

 

Added fuse numbers on the Photo of the Luggage Fusebox (White numbers) and modified Photo display of fuses to match the 1998 Luggage Fusebox list from 1998 XJ Vehicle Care Handbook page:
https://www.dropbox.com/s/xwu58gpw92...ss%20Photo.jpg

Here is the Luggage Fusebox list from the 1998 XJ Vehicle Care Handbook:

https://www.dropbox.com/s/7aelgzha9q...%20Fusebox.jpg


Jim Lombardi

 

Please note I revised the JPEG files and their weblinks in post 10 to reflect the correct fusebox -fuse numbers & fuse amps in the Photo to reflect the ones in the 1998 XJ Vehicle Care Handbook.

Jim Lombardi

 

[QUOTE=jimlombardi;765257]Please note I revised the JPEG files and their weblinks in post 10 to reflect the correct fusebox -fuse numbers & fuse amps in the Photo to reflect the ones in the 1998 XJ Vehicle Care Handbook.



Ok, a bit of an update.


I find no fuses bad, not whatsoever. Double checked.

I did find the module, under neath the box that holds the fuses.

So, unless its a relay (which I think are the little brownish plug ins), I suppose I need to start shopping for a module. I am going to have a friend try to test it. I took it out to bring it to him and then and only then, he tells me he needs the entire car bc he has no way of getting power to the module without the car.

Thanks for the responses to all.

 

Hi John
If your determine it is the Security and Locking Module not working properly then you
might try sending a private message to forum member Jack Shaheen (ask him if he is willing to repair the ciricut board for you).
I copied this information of one of his earlier forum post (6/25/13):

If you have an XJ8 around the 2001 year then yes I can fix it.
I no longer have my XJ8 but do have some parts to repair these modules.

another one of his posts (5/12/2009) Thread is https://www.jaguarforums.com/forum/x...e3/#post114254:

If you are good at soldering you can fix yours too.
I had the same problem with my controller.
No brake light on the right side.
I checked everything first to make sure it was the controller.
Just swap the lights from side to side and check wiring to narrow it down to the controller.

I then took the controller out of the car and with a little trouble managed to get the case apart to look inside.
I spent some time tracing where pin 3 (right side brake light) went to on the circuit board.
There are three chips right next to each other with the markings "BTS409L1" on them.
These are the chips used to drive the power to your brake bulbs.

Now for the really cool thing.
The one in the middle is not used in my car at least for anything.
There are no connections from it to the connector(s).
The on to the right of the middle chip is for the right side and the one o the left is for the left brake light.
So what I did was unsoldered the legs on the right side chip (the one that was bad) and also to the middle chip.

Then I used some wire wrap wire to solder the legs on the middle chip to the circuit board where the right side chip is sitting.
You can't remove the chips from the board. Really weird I have never seen this before. They must be epoxied on the board. Really strange.
Anyhow I put it back in the car and now have right side brake (and left) lights and NO nagging messages on the driver display.

Not to mention saved about $800

Really bad design IMO


here is a weblink to forum member jackshaheen:
Jaguar Forums - Jaguar Enthusiasts Forum - View Profile: jackshaheen

Jim Lombardi

 

Jim:

That is very good news.

I did learn that the call will not start with the module out.

That was embarrasing.

But, I am supposed to plug it back in and get it started tomorrow.

A friend said he knows how to test these and also the relays.

But, if I confirm what I think we all know is most likely true--I am going to need a new module or have it repaired for sure.

Its absolutely amazing how complicated cars have gotten and I think they are worse for it.

The amount of electrical issues on my 2001 7 Series just damn near ruins an otherwise fun car.

 

Now you know why I switched from BMW to JLR . . . And the new ones are a nightmare

 

Just a guess- I bet it is not the SCLM-

 

Oh, look at that frayed wire . . .

 

I'll side with Ross on this one ;o))
Over 98% of these 'problems' are always down to wiring chafes, bad earthing or dodgy relays.
Relays especially are a weak link in the chain as they age....they are after all an electro-mechanical device and are prone to failure as they age.
Just consider for a moment, these veeeehickles are now 10-15 years old and as with all 'modern' cars have replaceable 'consumables'.

Atmospherics, corrosion and dodgy batteries are high on the list ;o]

 

Uh oh.

I am not seeing any sign of corrosion or questionable wiring. In fact, the whole fuse box and underside of the fuse box looked remarkably clean.

 

Did you get around to testing the relays?