This is killing me. This is with HEADLIGHTS OFF. Turn on left blinker, the blinker works fine until I step on the brake then the left blinker is dim and right brake light (LED) flashes dim with the left blinker. Turn on the right blinker and everything works perfect. This is where it really gets confusing. With HEADLIGHTS ON, turn on left blinker without brake lights on and the right tail lights, the license plate lights flash with the left blinker. Apply brakes and the right brake light flashes with the left blinker. Only the right reverse light works with or without headlights on. Swap tail light assemblies (left to right) and it's the same scenario on the same sides. Sometimes after driving the car awhile everything works fine.

 

Have you checked the fuse for the brake lamp circuit?

Have you checked the earthing (ground) points?

 

Thanks for the reply. If the fuse is in the panel by the battery, I did the best I could without an owners manual or repair manual. I bought the car 2 weeks ago. I am the 3rd owner. The ground was the first place I looked. What does the rear body control module do?

 

What you are describing are the classic signs of a bad earth (ground), and maybe more than one.

 

You are right. I cannot find where the bad ground is. I own a 89 xjs and a 2000 xjr. So the ground is the first place I looked. Because there is no common link between the lights with the problems (brake, reverse, blinker, fog), it has to be a ground or a control module. I don't have a wiring diagram yet. Thanks again.

 

Check the ground at the connector coming straight off the back of the tail lamp inside the trunk. If you put in a jumper wire on the ground, and put it to a good ground connection in the trunk, see if this helps. Just might need to do a wire repair and run a new ground wire.


The REM controls a lot of different things for the rear of the car, as this car and the S-Type are what Jaguar calls Zoned Partition, meaning, the REM controls everything in the rear of the car, and the front or general electronic module controls everything in the front, such as lighting. Haven't seen any issues on these cars with the REM's. When checking fuses, always pull them out and look at them.


Looking at the wiring diagram, the rear lights aren't fused themselves. Most likely a faulty ground.

 

I would also suspect the REM. Since the car uses a switched ground system the circuits are live all the time and are only completed when the REM provides the switched ground.
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The REM is what I think it is. I have a replacement coming soon. I will update after I install it. Thanks

 

It's most likely the rear fusebox by the battery, had similar random light issues and replacing the fusebox cured them all. I first tried a used REM but these cant just be swapped out and would need recoding to your vehicle.

 

I just looked at the rear fuse box. I see it has a circuit board in it. Was the circuit board itself that was the problem? Did you buy a new fuse box or buy used off Ebay? Thanks

 

Hi, yes I believe the problem lies in the pcb on the bottom of the fusebox. Because I needed my car I just ordered a used fusebox complete with fuses off eBay for around £20. Took me about 15mins to swap it out and I was amazed it had fixed it, I too was at my whits end with it and found the idea of the fusebox after googling around one evening, it seems to be becoming a fairly common fault.

 

I just ordered a fuse box off Ebay. You are right, the REM did not fix the problem. I'll let you know how it comes out. Thanks again!!!!

 

Yeah I have a spare REM now too! Hope you get your fusebox soon.

 

We see no fuse box problems at all.

Was the REM programmed? You can't just plug them in.
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Update on my tail light problems. Replacing the rear fuse box with a used one from Ebay fixed all the tail light problems. I too now have an extra REM. Thanks Aaron 3.2, you were right on.