I have a non-working driver rear brake light. Center mount third brake light works fine, passenger rear works fine, so I suspected SLCM as the likely issue as opposed to the brake switch. I purchased a replacement SLCM and put it in, but it did not resolve the issue. Shame on me for not pulling out a multi-meter before buying parts. I can actually program my remotes now, so all is not lost. However, I still need to figure out what the issue is with the brake lights. When I probe the red/orange wire going to passenger brake light - it returns close to 12V with the brake pedal depressed. When I probe the blue wire going to driver brake light - I'm getting right about 5V. Putting the other SLCM back in gets the same results.

When an SLCM goes bad, will the failed brake light still get some voltage, just not the full 12V?

What is my next step to look at?

Any thoughts would be much appreciated.

 

Have you checked the wiring harness on the right side support arm of the trunk/boot, there is a known short there.

 

I have not checked there. I assume I just need to trace the harness up from the fuse box and inspect?

 

I have not checked there. I assume I just need to trace the harness up from the fuse box and inspect?

 

Its generally found right on the curvature of the support in the loom. Here's an old link on it... https://www.jaguarforums.com/forum/x...orking-193530/ ..Post #13 shows a pic of the arm effected...but review the thread in case something catches your attention.