Good morning, first time posting so I hope I’m doing this correct and hope maybe one of you all will be able to help me…

I have a 2000 Jaguar XK8 convertible with approx 70k miles, I have had it around 16 months. I noticed last summer that the brake light would always stay on. I needed to fix it but it was on the back burner. Anyways…around late last fall, it was always dead. And the cluster was always messed up. Like the Speedo would show 70 mph just sitting there and the gauges were all over the place. It would also say some thing about the gear box and sometimes it would not come out of park. I could turn it off, then turn it back on and get it out of park no problem. I can jump it and drive it for hours no problem, but as soon as I turn it off, deader than a door knob, not a single light comes on. So I had it in the garage over the winter, Friday it was sunny and I decided to get it out and go get a new battery and get it cleaned up. Did that and it did great, cluster was still all over the place and still had the issue getting it out of park but I stopped several places and every time I came out, it started with no jump. Saturday morning I go outside and start it up and it starts great, but, it won’t come out of park, so I turn it off then go to turn it back on…nothing, not a single light comes on, nothing. So I jump it, and it drives fine, but as soon as I park and turn it off, dead again. Any ideas? Any leads would be greatly appreciated!

 

I would start by reading the OBDII codes. You may have gearshift alignment issues, but reading and reporting your OBDII codes here would help us get started with attempting to provide assistance to you....

 

For the brake light issue, if you are sure the parking/hand brake isn't on it could be a switch problem. Either the switch itself is faulty or the plate is stuck. Inbetween the door and brake lever you should see a black push in/out spring-loaded button. If you can push it in and the light goes off the plate is stuck/broken. Some have fixed this issue with some WD-40 or rust penetrant. At the base of the lever are about 1/8" thick plates next to each other. One of these depresses the switch and just needs some lubrication. Another option is to unplug the switch which will turn off the light.

 

Well a battery cannot go from fully charged to fully discharged instantly. Even though its new I would give it a charge as often they can stand for months waiting to be sold ..look for a date code on it to find the manufacture date . There is a tiny possibility that it has a faulty link bar inside the battery so next time its dead read the voltage across the lead terminals on the battery ..( not the connectors )

 

I've been lurking on this thread because I'm hoping someone comes up with a universal solution for the battery/brake light/locked gearshift issue.

My zombie (undead) 1997 XK8 has suffered similar problems, In reading the OP Cvagheel's post (or is that the OG?) I'm not convinced the problems are the same. But let me describe my similar issues and share my thoughts: Perhaps there is a common glitch in the system that can be solved.

If you would like to save five minutes of your life and not read further, my thought is that the problem lies in the shift lever. If efforts to fix that fail, then I suggest spending $170 to replace the brake switch to see if that solves it. I agree it's a terrible, expensive and probably futile solution, but it's my best take.

Here are my thoughts this issue:

Similar Problems:
1) My brake lights occasionally come on at night, whenever the ghosts demand it.
2) My brake lights often, but not always come on when I disconnect and re-connect the battery, which I often do to prevent problem 1 from running down the battery.
3) My gearshift lock would never unlock when I got the car. Documentation from previous mechanics indicates this problem had been unsolvable. (The previous owner jammed the lock open with a small pencil.) Also, there was a fellow on the Forum who posted about his similar problem for about a year, then gave up. I fixed mine by hotwiring the brake switch to the transmission lock. It works, but there is always a click when I tap the brake.
4) Past issues with bad grounds have caused non-start issues.
5) Issues (twice) with the neutral safety switch will cause a non-start, intermittently at first; finally when it wears out. It has nothing to do with a dead battery, but the effect is the same. This is the big switch that bolts to the side of the transmission and switches drive ranges electronically.
6) Issues with shifter alignment, as previously noted, can prevent the car from cranking.

Possible Solutions:

1) I'm really interested in the parking/hand brake switch disconnect solution to the brake light on problem - which could cause the battery to die. I never use my hand brake because it usually hangs up. However, as noted, my car suffers from brake lights that occasionally turn themselves on for no apparent reason. Rollins, can you elaborate on your solution? I had no idea that the hand brake had any connection to the brake lights.

2) It is likely that there are two or three unrelated problems at hand here.

A. The non start could be caused by misalignment of the shifter cable or a faulty neutral safety switch. I suggest Cvagheel (the OP) measures battery voltage when the next non-start occurs. It's possible the battery isn't dead at all.

B. Our common brake light on issue may be caused by a faulty brake switch. A short in the brake switch, or misalignment, may be causing problems throughout the system.

C. The transmission lock out problem may be unrelated, or it may be related to the shifter cable/neutral safety switch issue..

In conclusion, I've addressed each issue in my own car with the exception of replacing the brake switch. If it were my car (and it has been) I would focus on the shift lever issues first. If all else fails, I would replace the brake switch ( but you may be tossing money into the wind.)

I'm really anxious to read how the OP solves the problem.

 

TSB for you.