More issues with the brake lights on my brother's car. Not sure if it is in the system or in the wiring from recent repairs.

Sorry for the long story but I'm making it as short as possible.

When I was first introduced to the car, my brother had a brake light that would not go out. So he was pulling the bulb every time he parked. I disconnected the power wire to the light and slaved the power to that bulb from the other side. That worked for a while. Someone on here told me that could strain the system and would likely cause future issues. I did not know of another option so I left it like that. At the time my brother expressed no real interest in the car. He was acting like he was waiting for it to drop and move on. After I expressed to him how nice the car is, it slowly changed his mind.

Anyway, last month he put the car in an upholstery shop to have the roof liner replaced. One thing lead to another and they refurbished the entire interior, except for the seat leather. New roof liner, carpet, custom floor mats, door panel carpeting, etc. Now the tail light brake lights do not work.

I'm not sure if this is a new issue or a continuation of the old issue. When I press the brake pedal, the HMBL works but the brake light in the tail does not. It does NOT get power at this time. The passenger side brake light wire still has full power ALL THE TIME, but the drivers side never gets power.

So, did something else simply die in the system or did the upholstery shop damage something? Is there a way for me to check the system or wiring?

Here is the video of my previous repair to the brake light (hack job).

 

I suspect that the roof work is just coincidence, have you checked the brake switch, and earth leads?

 

Sorry for the delay in my response. I'm traveling.

Not yet. The light in the back window works, and the passenger side light has full power all the time, so I assume the switch is working.

 

If the centre light is working, then I guess you might be right that the switch is working, but I would check it anyway. Then I would take the bulb out of the Continuous on lamp and check the socket. It's getting power from somewhere. Get a needle and pierce the cable and check with a meter. Sometimes people force the bulb in the wrong way round.

 

The security and locking module in the trunk has two circuits, one for each brake light. The are separate so that a blown lamp can be detected. It is a known failure mode for a circuit to short and cause one bulb to remain on. I suspect you have now burned out the other circuit.
You can either keep hacking or buy a SCLM off ebay. The Key transponder function is not in this module, but the key fob is, so you need to get a module with the same fob frequency, or get the fobs with it. If you get the same year model SCLM, your fobs should program to it just fine.

 

Back in town, the trip was WAY LONGER than I expected.

Anyway, The subject car is a 2003, there is a 1998 in the junk yard. The numbers on the box, under the fuse box, is different. What are the odds of it working? Also, this is the box I need that controls the brake lights correct?

 

On another note, can I bypass the box and wire them up direct from a signal, power pre module? (Seems like it's over engineered to me).

 

Robert, I had just the opposite problem. The right brake light would not come on, and I kept getting a check rear light message. Ross advised that the SLCM was the problem. I found a used one that matched the part number and the frequency 315 MHz for my remote fobs. Previously I had applied the temporary fix, as you described in your video, by bridging from the left light to the right.

Ross suggested that a better bridge would have been from the brake light relay that powers the upper brake lights. But I bid on a used SLCM on eBay that matched. Cut the bridge, spliced back the rear right wires and installed the purchased module. Everything works fine; used your video for reprogramming the remotes.

But, I think Ross' suggestion to bridge off orange wire to the upper brake lights would have worked, too. Your brother would still have the check rear light message.

There is an outfit in Idaho that rebuilds the SLCM for $200 and guarantees for five years. Takes about ten days round trip if he can do w/o the car.

 

Could I have a bad relay?

 

XJ8 2001+2002 Elec Manual.pdf

Probably not. Here is the wiring diagram and SLCM wiring

 

The early module you referenced will probably work EXCEPT you will need the key fob with it, I believe. In my case, the MY 99 SCLM worked on my MY 02, but the fob frequency was different. So- you could not marry the fob to the car. The fob from the donor car worked fine, though.

Overengineered? Well, you could build a car without brake lights that flashed with the alarm and you could do away with keyless entry and security, and eliminate the other electronic "amenities", but then you would have a Pinto, huh?

 

LOL, You have a point there. So, the brake lights flash with the alarm system. I'm an old red block Volvo guy at heart. Over 400,000 miles at $176.80 per year worked great for me.

As always, thank you guys very much for the help. I'll test the wiring to see what is going on. A guy in Australia said he has a unit for me. Maybe it will work LHD. LOL

 

I spoke to a high level electrical repair guy for issues like this. He works on all kinds of European cars, Audi, Jaguars, Volvo's etc. He highly suspects that the SCLM has bad solder joints. Said I can pull it and press on the board is different spots to find the bad ones, then try to refloat some solder on it to fix it. I've seen this a lot in cars and computer.

On an HP computer, I usually pull the mother board, stick it in a pre-heated over (350 degrees) for 3 minutes. That usually heats the solder up across the board and fixes the issue. I wonder if that will work for this???

Just remembered that the remote function is partial. Locks the doors sometimes, opens the trunk, but does not unlock the car. So the SCLM has issues with that as well.

This is what I'm going to try to do... Take the '98 SCLM and see if it will work with the key. All brake lights etc. If it does, I'm going to pull the board in the current one, drop it in the oven, and see what happens. Then report back. Wish me the best. lol

 

Make sure the frequencies match: you should be at 315 Mhz. If your thingie works, I may try it, fix mine, and put it on eBay.

 

The frequency is only for the remote correct? I'm pretty sure they are both 315 Mhz, but I think the remote freq is elsewhere on the box. The FIC #.

 

Rgr, tower! For remote. Freq will be on the replcement. 315 since mid 2000, which is what your SLCM has.

 

My guess is that the '98 had it's box replaced.

After replacing the box, everything works except the remote. I took the old box and baked it, that did not fix it. Still had the right brake light on all the time. The old box had been worked on before, had marks and writing on it (the board).

 

You should read what you are told and read the archives instead of relying on some smart guy that works on "all kinds" of cars.

The shorted HSSS in the SCLM is a well known and documented problem and many of us have fixed them. I assure you that baking the SCLM like a pie won't do it!

 

The XJ8 keyfob transmitters and SLCMs have 2 different protocols. 1998-2000 are compatible and 2001-2003 are compatible.

They are NOT interchangeable.

bob gauff

 

I have read what was posted here, but did not see any mention that "many of you have fixed them". All I seen was mention of replacement.

Not sure what a HSSS is, but I will take a quick glance around. I'm not a electronics guy, and really don't have time to learn that much about it with my current life load. But if this removed module can be fixed, that would be nice. Probably easier to purchase a remote for the '98 SCLM. Chances are, I'll read right over the HSSS repair and still not understand it. Those things are often above my pay grade (which is not hard to do). However, reading through 8 years worth of forum post can be time consuming. I've already been messing with this issue for almost 2 years and this is the first I heard or read about a HSSS.