Have been searching forums for a while, trying to see if anyone else is having this problem. For the last six months or so, maybe 3 or 4 times, I'll go to start my XK8 and it won't start. I have power but the engine will not start at all. I get 4 messages: ABS Unavailable, TRAC Unavailable, Gearbox fault and Engine Failsafe Mode. I originally thought it was a problem with the shifter not being in park, but oddly it seems that if I wait 15 minutes, almost exactly and try the car again, it starts normally and will continue to start until this problem surfaces again. My mechanic put it on the computer and didn't get any faults that would point to this issue. Anyone else ever experience this? Driving me (and my mechanic) crazy.....

 

will it turn over? does it just click and you hear crickets (silence)?

 

Doesn't turn over, no clicking, nothing. Can turn on anything as there is power, but no engine start.

 

Little recent info. Spoke with one dealer, who suggested that the reader in the ignition that reads the chip in the key may be failing. His explanation seemed spot on except there's never been a fault for that when the car was checked. I've switched to my spare key in the off-chance it's the key and not the reader but figure that's a long shot.

P.S. Love my Jag, but am absoultely clueless about anything except the most minor repairs, so I'm probably going to mess up terms and such, sorry.

 

Next time it happens move the shifter to N. There is a micro switch on the P position (and the N) that will prevent the car from doing anything is it is failing or is out of adjustment.

If the N works you need to clean/adjust/replace the micro switch.

 

...the switch, called a neutral safety switch, is rather expensive though, i've looked around extensively on the internet, over $400 for the part alone. (at least on my car) yours may be different being a 2002 on a ZF 5HP tranny.

 

Yep, that's exactly what a non-Jag mechanic came up with as the problem since it wouldn't start even in neutral, but I've had two Jag mechanics tell me the problem isn't with the shifter/transmission. Going to ask about the micro switch, though, thanks!

 

Also, just on the off-chance, have your battery checked at rest and under load. Low voltage causes numerous fault/failsafe/limp mode displays. I speak from experience.

 

Hard to say what is going on with the car. Am I correct in that your starter does not engage and does not turn the engine over? If that is correct I would begin checking power to the engine compartment and starter. http://www.gusglikas.com/images/Auto.../jagxk2002.pdf Page 17 shows the main feed to the entire car. Once the power leaves the battery it goes to the high power module. In that module you have one feed to it from the battery and two leaving, one to the starter and the other to the engine management fuse boxes under the hood. You need to see if power is reaching both the starter and the fuse boxes. The boxes have easy access the starter is another story. In the past we had a few cars that had a problem with the power leaving the high power module. What we found it that the tire was loose in the trunk and would strike the module causing it to loose continuity (cracking) causing the no power. Like yours it would have a mind of its own and only leave you stranded long enough to make you wonder why you have the car. Check this out first and see what you have. Now keep in mind that it will look good and seem tight you should check it closer. But before you mess with it pull the battery cable, a 12voly DC flash is nothing to mess with. As for the Codes you are getting you will get them when the battery goes down or weak and a loose or dirty connection in this module can and will cause the same problem. Keep us posted. Good Luck!

 

The usual problem related to those messages is a throttle body failure. My guess is the probelm is there.

 

Sorry, been away. Since the post, I had it rechecked. TCM, ECM and all connections checked and redone. Battery tested ok, and had connections cleaned. It was put on the computer and gave two codes, P1797 TCM to ECM and U2500 Can Bus error ABS. Both faults cleared. This was about 1 week ago and no problems since, but I'm still not convinced that it could just be a loose connector or battery problem.

 

Sorry, been away. Since the post, I had it rechecked. TCM, ECM and all connections checked and redone. Battery tested ok, and had connections cleaned. It was put on the computer and gave two codes, P1797 TCM to ECM and U2500 Can Bus error ABS. Both faults cleared. This was about 1 week ago and no problems since, but I'm still not convinced that it could just be a loose connector or battery problem.

 

Well, haven't posted in almost a year since, Jag has been problem free since last October. Then two weeks ago, same thing. Turn key, car has power but no crank to engine at all. Happened again yesterday, after using the car maybe four or five days with no problems. Tried moving shifter and starting in Neutral and no start. Waited 15 minutes both times and car starts with shifter in park. Honestly, at a complete loss as to what it could be other than gremlins, lol! Planning on replacing the Neutral Saftey Switch AND the key reader in the ignition but really not sure that will help. Thought I'd post again to see if anyone else had any progress with the same problem.

 

I had the neutral safety switch issue over a year ago, for about 6 months, there were times almost weekly that I would be forced to jiggle the j-gate in either P or N to get it to start. I was pre-planning on its replacement...then I did nothing. It hasn't acted up ONCE in over a year, so I am leaving it alone.

try the jiggle, not just up/down selection of the gate.

 

This is just a hunch, but it's worth a try. It worked for me. Go to the battery and tug on the red wire. Then try to start the car.

I was having similar problems; every once in a while my car just wouldn't start. It wouldn't crank, it wouldn't even click. If I would just ignore it for a few minutes, the car would start right up. But I was also having a situation where my headlights and interior lights would flicker at times. On two different occasions, the flickering was followed by a complete power failure in the car in which everything went completely black for a moment. Both times it happened, it happened at night on the interstate, so it was a little scary.

The last time the flickering started I pulled out my Android phone, which also functions as an OBDII reader. I pulled up the voltage display and it was rapidly fluctuation between 10 volts and 14 volts. The program I use actually has a graphing feature, so I was able to graphically see the flickering on the graph. I also had my multimeter in the car with me, so I pulled over to read the actual battery voltage with my multimeter. It was reading about 13 volts steady, so I figured there must be a loose connection somewhere causing the flickering. I went and sat down in the drivers seat and tried to start the car and it was completely dead. The interior lights and dashboard lights were on, but the car wouldn't crank. It wouldn't even click.

I then went back to the trunk and jerked on the red wire, and I also tapped on the positive and negative clamps with the handle of a screwdriver to make them move slightly. After that, the car started instantly, the flickering was gone, and the OBDII scanner was showing a steady 14 volts.

That was over a month ago, and I've had no flickering or starting issues since then. All I can figure is that the clamps weren't making good contact on the posts, or the other end of the red wire wasn't making a good connection wherever it terminates. Jerking on the wire or tapping on the clamps cleaned up the connection and got everything working again.

I bet Gus drove down from Virginia late one night, snuck into my garage, put dielectric grease on the battery terminals, and then drove home without ever telling me.

 

lol

 

Thanks, Rev. During one failure I disconnected/reconnected the battery with no result, but will definately try your method. The issue that really has everybody puzzled is the exact 15 minutes it takes every time and then the car starts. One non-Jag mechanic thought maybe the ignition exciter ring could be failing/have a fault and that when it doesn't read the key it prevents the car from starting and then resets after 15 mins. I thought this too good and easy to be true and checked with a Jag dealer who never heard of such a thing. (of course, lol!) Not sure what else could cause that. Seems a short or a bad connection would be more random than precisely 15 mins each time it fails.

 

Had I done that or you used the Dielectric grease you would not experience problems (poltergeist) like that Sam!

 

Just brought a 2000 XJR a few days ago, and it was fine without any issues. Then it had similar issue with not able to crank at all.

I put the key to ON position and these are displayed:
Brake Fluid Low, ABS Unavailable, Transmission Failure, and Engine Failsafe Mode.

I checked the brake fluid, it's full.
I turned the key to crank, no crank at all.
I tried again, and it would not allow the key to turn at all. (seems something is blocking it)

The shifter is stuck at Park, I can't move it to Neutral.

I checked all the fuses, all OK.
After messing around a bit, I magically was able to shift to N, and the car started right up! No more engine lights!

I let the cat ran for a minute, then shifted to park, turned the car off, and can't start up again.
I cycled the key switch and it show the same symptoms mentioned above.

What is going on with this misbehaving Jag?? Please help.

On a side note, the guy who sold me the car said to lock the car via the remote all the time, otherwise will have to wait 5-50 minutes before it can be started. However I locked it overnight and still can't start it.

 

Hey there, JagYi,

On the XK8 there is a little screw/bolt to the left of the shifter that you can remove and insert the key into to let you move the shifter out of park. I'm assuming it's the same on an XJR. I get the following codes when the problem happens:

TRAC UNAVAILABLE
ASC UNAVAILABLE
GEARBOX FAILURE
ENGINE FAILSAFE MODE

I've tried moving shifter to neutral to start but that doesn't work. Only thing I can do when it won't start/crank is wait the 15 minutes and then it's fine.