1999 USA model Jaguar XK8 Coupe (tl;dr: I think it's a brake switch but below is my notes)

Yesterday I noticed I have no brake lights (I forgot to check if I have reverse lights). None of the three work when brake pedal is depressed.

I do have the rear fog light. It works. Front headlamps, fog lamps, brights work.

Rear running light (the constant on when lights are on) works.

No notifications in the notification window.

Checked the bulbs and they pass visual inspection.

Removed a bulb and the notification on the dash said bulb failure (or malfunction or whatever it says when bulb is missing) so whatever in the computer that talks to the rest of stuff to identify when something is broken is working.

Changed the relay from the fog lamp in number 1 position in the trunk to number 5 position (stop lights). No change in operation - still don't work. Put number 5 (stop light) relay in fog light position (1) and fog light still works - so relay works.

Visual inspection of ground wire on each side didn't show deterioration.

All signs point to: Brake switch has failed at the pedal - but posting to see if there is anything else I can check or am missing?

ETA: Car is equipped with cruise control. I've never used it, but the light comes on when I depress the button on the center console and there are no warnings.

 

I think you've got it.

 

I can't help to notice you didn't mention checking the fuses...

 

Good catch.

I checked every 5a fuse just to be extra certain!

 

Just to confirm, there are two 5A circuits for your brake (“stop”) lights in the boot fuse box.

 

Replaced brake switch with new one (RockAuto - about $78?).

Did the remove bottom nut, swing old switch up and out and replace with new method. Finding the tiny zip tie to cut was biggest issue in removal. Lining up the new switch to catch the upper nut took numerous tries and contortion.

Maybe 30 minutes? Didn't screw around with replacing microswitches, etc. I can't solder to save my life anyway.

Got brakes - except for third brake light. It doesn't work I guess.

 

The Stop Lamp Relay powers the LEFT/RIGHT stop lamps and the HMSL BOTH but through different fuses.

If fuses are good, then the HMSL or the wiring is faulty.

 

^^^ This.

I discovered a PO had done a super-bodge to get mine to work, but failed to address the license plate lights. I wound up replacing the entire trunk lid harness with a good used one from NOMA and all is good again.