There is an older thread about the various cures for this problem but only one of the posts came close to identifying a possible simple work around if this happens to you...as it did to me. That earlier thread hinted at the possibility that there was a 'release' hidden under the shifter plate but the poster wasn't sure just where it was. That gave me a clue so looked in the Car Care handbook on page 26 (mine's a '99 XK8) and it states how to get the shifter unlocked if it's a failure of the internal micro-switch.

It couldn't be simpler. Just to the left of the shifter on the panel surrounding it is a STAR fastener. It's made of plastic so don't go Terminator on it. A T-30H fits nicely. It isn't in there all that tight so take it easy so as not to strip it. Back it out and you'll see a hole going into the panel. As you turn the ignition on to start the car have a slender rod or other tool you can push down with and insert that in the hole and GENTLY push down on the micro-switch contactor. You'll can eel some slight resistance or push-back as you lower it. Keep it pushed down (no mashing here) as you slowly rotate the key to the run position. The shifter should come free and you can move I back from PARK. DON'T go into revers until you've released the pressure on the switch.

It's possible that it will never happen again but it's more likely that the switch has gone bad and will need to be replaced. I just worked this out this morning so I haven't had time to take the shifter panel off and try to clean or adjust the switch but I'll post back whatever I finally get figured out.

This forum and the owner's manuals and service manuals are worth their weight in gold as they've saved my hundreds of dollars over the past 2 years so I'm happy to contribute whenever I can.

 

RD,

If pressing the hidden microswitch released the gear shift, then that microswitch "is" working. I wouldn't try replacing that one.

I'm not an expert on Jags, but on many cars the locking solenoid for the shifter won't release until you have your foot on the brake pedal. I would check the brake switch first. Hopefully, someone with specific knowledge of this will weigh-in, but in the mean time try letting your brake pedal "pop" back into the up position a couple of times and see if that makes a difference. It's a long shot, but it might save you some time and $$$.

 

Activating the micro-switch manually doesn't mean it works, it just means that the electrical connection that is forced by my applying pressure is doing it's job. What ever activates the switch so that it makes that connection is what's failing. I had already checked the brake light circuit which was fine and in addition there is a starter interrupt that won't let you even start the car unless your foots on the brake and my car was starting so all those circuits were O.K. Also, every other shift in both standard and sport and both in full auto or in manual J-gate mode were right on the money per their spec's speed and RPM's so obviously the fault lay in the shifter and the micro-switch itself.

Jaguar themselves recognized this possibility and made an easy way to bypass a bad switch by putting the Star fastener right over the switch and giving instructions on its use in the supplied Car Care manual.

There are several possibilities for a tranny acting up such as mis-adjusted cables. loose cable mounting bolts, etc. but only one that would allow you to start the car but not be able to move the shifter so much as 1/4". That's the micro-switch circuit failing to actuate. Since I had already checked the appropriate fuses that left the switch itself as the most likely cause and by using Jaguar's convenient work around I was able to go wherever I needed to today.

Tomorrow I will access the switch itself and test it for continuity and voltage pass through and hope...yeah sure......that a good cleaning with electrical cleaner will fix it. It's a 15 year old car so this **** wears out.

 

I would have to agree with you if you were manually manipulating a release that's supposed to be solenoid activated. Essentially you'd be taking place of the solenoid's function (and it's associated circuitry). However, If the switch in there is specifically intended as an alternated method of releasing the shifter when the normal circuitry fails, then that hidden switch is performing its intended function when you press it. However, like I said, this isn't my specialty - I'm just relaying how many other cars work.

But, however it turns out - make sure you post your results. All info is good info.

Good Luck!

 

The term 'micro-switch' really isn't correct when referring to the shifter. It draws a usable picture but there is really a solenoid that get activated by the Body Processor Module.

Anyway that solenoid can and does get out of adjustment in that the arm that extends from it to trip the shifter interlock slipped too far away to do its job. There's a relatively simple adjustment for that done through the top of the console without having to jack-up the car or do major surgery.

In my case that all proved unnecessary as while doing my pre-wrench study I also tracked the electrical circuits from the BPM since it looked as if the solenoid was energized through the BPM. It tracked back to two 15A fuses located in the driver's side fuse box at positions #5 and #7. The fuses looked fine on a visual but I decided to pull them anyway and when I pulled the one from #7 it was definitely blown.

I replaced it and PRESTO my shifter was unlocked. I had checked the manuals for the location of any fuses but had looked for fuses controlling transmission NOT ones that controlled 'solenoids'. My bad.

 

@RDMinor I realize this is a very old thread, however I am having similar issue and am just getting to start the troubleshooting process. I see the solenoid, and it seems like it is lined up fine with the release bar. I will check fuses 5 and 7 on the driver side next. If the fuses are fine, where in the BPM would I check to see where the cable to the solenoid originates?
Also, I am assuming the brake switch is working as I see the brake lights light up. If this is a poor assumption then any ideas where I can find the issue from the brake switch (if that is the issue)?

Thanks in advance!
Robert

 

JagX100...You're right this is an old thread and I had to do a little quick brush up on the subject. Since I don't know specifically what year your XK8 is or it's specific power train I think the best thing is to guide you to the more specialized .pdf files that contain the electrical schematics and their pin outs, etc.. Mine is a '99 non-supercharged 4.0 so what I might describe might be different from yours.

If you wish and can use the '99 file send me an e-maill address and I can send you the file OR check in the 'stickies' section to see if a copy has been posted there. If you have a different year look for an appropriate download of the file for your model... it will be named something like this ...jagxk1999 Electrical.pdf with only the year being different.

If you have a '99 and you get the file either from me or a download then locate or search Body Processor Module.

For the '99 the best schematiic is probably numbered 03.1 titled "Battery; Starter; Generator: AJ27 N/A" there you'll find the BPM with all of it's connections for those 3 processes including the starter functions which you'll need. I think the visual is worth a whole lot more than anything I can write and the schematic is simple, includes pin #'s at both ends of everything it connects to without including anything not related to the 3 items in its title. In addition with the file there's plenty of info on how to decipher anything you don't understand even if it takes a bit of homework.

Anyway I'll be happy to e-mail you a copy of the file but you'll need a copy of Adobe Acrobat Reader DC (it's free & easy to goggle) for whatever operating system you're using. You can use the forums system to e-mail me your e-mail address and I'll send it by way of a reply.

 

Thanks@RDMinor ! Strange, I thought my signature would show up with the year and model of my car. I will check to se what I missed.
That being said, I have a 2000 XK8, 4.0 automatic. I found the '99 Electrical pdf, will review it tonight and see if I can find the details I need. I might actually create a YouTube video of this process, as I couldn't see any videos that illustrate going this step, though there is a nice image in one of the other threads on this similar issue.

Thanks again,
Robert

 

It's likely that not a whole lot has changed so use the search function to find that particular schematic I mentioned. It might even be the same number. You probably already know where the BPM is located and it isn't all that easy to get at at least not for an old fart like me but between that schematic and the applicable service manual and its illustrations of the solenoid itself you'll figure out what wires/circuits to check. I'd probably still defult to double checking the solenoid adjustment being out as it wouldn't take very much to throw things out of whack.