When I start the Jag, I turn the key to the first position, wait for the chime to finish, and then turn to start. On occasion when I have turned the key immediately to the start position I have gotten a temporary warning message. Is this normal?

 

I also posted about this earlier. I have been doing this since I have a 7 year old battery that is still in decent shape. When I start quickly it results in random error messages but when I do as you describe, typically no messages.

 

What is the chime - is that a US thing? I always just start it, and never have any problems.

 

Someone more knowledgeable can “chime” in, but I suspect this brief delay allows the ECU to run a quick diagnostic check. The chime is likely a fasten seat belt warning.

 

same here.

 

What's the error message? TRAC Unavailable?

 

It’s been a while. I don’t recall but that may have been the message.

 

If its Trac Unavailable its caused by one of two things - low battery voltage at the moment of cranking (doesnt have to be particularly low - mine does this from time to time even with a new battery, if i let it sit for a week or so) and/or the soldering on the power connector for the ABS control module is cracked and starting to have poor continuity - a known issue with these cars. It can be both. the soldering on the ABS module on these cars is a known failure point and WILL break. its not a matter of if, its when. Quite easy to fix if you know how to solder and arent afraid of bleeding brakes.

John from to the garage did a great pair of videos on this.

 

Luckily no bleeding is required..

 

I don’t think an inadvertent message has appeared on start up since I started using a battery trickle charger on a regular basis. Best $$$ we ever spent on XK8 maintenance!

 

In 25 years, I've never seen an error starting without hesitation of key rotation.

 

Coming back once again to this topic, I have had pretty good luck eliminating the random/bogus error messages by pausing the key before cranking with my now 8 year old battery. But occasionally after driving maybe 15 minutes more or less some bogus message will pop up like the "check rear lights cruise control not available", etc. I found this strange since my little cigarette voltmeter shows 14.5 volts which I suppose is what is being generated by the alternator. But are the circuits-in-question still somehow sensing that the battery stinks and that is triggering the bogus messages? The messages are always gone the next time I start the car.

 

Even on my ‘15 XKR, if I just jump in, press the brake pedal, and then immediately push the start button it can lose its mind. Im careful to follow a very predictable start sequence:
1) Get in the car, and close tbe door
2) press the start button to put it into ignition on mode
3) wait for all the various sound to stop as everything is booting up
4) press the brake pedal until the brake switch is clearly activated
5) press the start button, and wait until the idle drops to normal before diving off.

DO NOT PUT THE CAR IN ACCESSORY/IGNITION MODE FORCAN EXTENDED PERIOD, AND ALWAYS STARTVAN RUN THE CAR AFTER ENTERING ACCESSORY MODE.

Any change from the above and it might lose its mind. When that happens, weird things won’t , work including not engaging the starter. To correct, disconnect the negative then the positive battery cables and short them together for about 30 seconds. Then connect the positive cable then the negative cable.

 

This warning message suggests an issue with either the brake switch or cruise control switch or the associated electrical circuit. Sometimes, simply cleaning the bulb sockets in the tail lamps and installing new bulbs will resolve this issue.

P.S. My '03 XJ8, with the same engine and transmission as the X100, has sometimes exhibited the same behavior of fault message, typically TRAC Unavailable, if I turned the key to Crank without pausing in position II (RUN) to let the computers run their checks. But cleaning all the critical ground points and battery power connections and using a battery trickle charger has completely eliminated the problem.

Cheers,

Don

 

There’s a lot of straight up Voodoo and / or Black Magic involved in these cars.

Z

 

ha ha ha love it! and your right zray.

 

We’re driving computers, in essence, that just happen to have 4 tires and a steering wheel. Every electronic device I have I have to wait until it “boots-up” before I can use it. Usually just seconds though. See no difference with the XK8.

Brian W.

 

Don makes a good point about the grounds. Easy to check because they have and do cause strange symptoms.
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The problem is the battery is in the boot and the starter motor and computer are in the front, connected by a series of wires with joints in them. Corrosion at any of the joints will lead to voltage drop, especially at the high current the starter needs. Add on the extra load as the modules are all starting up and you can see why you might have problems if you don't wait.

 

Check the braided battery ground cable.

These are known to develop resistance and intermittent conductivity breaks without visual evidence of deterioration.

Perhaps enough to cause a temporary voltage drop when things are done too quickly.

At this age, I would recommend replacement with something more common (and reliable) by making up a standard copper cable.