Hello, I'm still new (9 Months) with my 2003 xk8 convertble. We have had a wonderful time with her here in the desert. with 59,500 miles she has been a purring. (oh, yesterday was the first day to go from the mild 70-80s to hit 103, just thought of that).
So today she doesn't start. I drove her three days ago about 20 miles at freeway speeds. She is bumpy with the last alignment for new tires in 2020 recommending suspension work. - That was going to be my first investment, probably a rather big one. right?
She came with an error "check rear lights, cruise not available" I was going to have the recommended switch replaced but wisely hesitated and as soon as I got an over-the-top estimate of 250$ to replace a switch and almost immediately the error gracefully stopped.
When I turn the key to on, then to start there is no response from the starter/engine, leaving it on I then can hear the engine fan come on and then the following:
Today's errors go from "DSC system fault". (Is that something I read as being a brake switch?)
a few seconds later the red break indicator lights with the battery symbol below.
a few seconds later "limiter not available"
and after trying again several times there once and briefly showed "transmission fault"
Have I entered the haunted era of Jag ownershIp.?
I did find the battery is reading at 12 volts. It was new in 2022.
I worked on cars as a kid rebuilding engines, switching out transmissions on fords and Buicks. At one time a farmer's bailing wire did a fine job holding the alternator in place to get me home - In the early 70s! In retirement I have left the only tools an old person needs under the sink and sometimes miss having a good drill. My mechanic skills and tools went away with my 1992 fiat spider in 1999.
So, folks any ideas of what I'm looking at or should be looking for? I love this forum and of course love this perfect car.

 

The battery voltage must be much higher than 12V as 12V represents a dead battery. With the XK8, anything less than a rested voltage, disconnected from the car, of 12.5V means trouble. Replace the battery with a new, fully charged one, and all the error messages will go away.

Richard

 

^^ Yep, your battery is toast. Time for a new one....

 

These things are very sensitive to battery charge. I have a fairly new battery in mine. Still, I found a lot of my strange problems went away by putting it on a trickle charger when not in use. My flag for low battery is the driver's window not returning to full up after using the door. I think my commute to work is so short that it wasn't fully recharging from cranking the starter.

And get yourself a OBD-II code reader ASAP. It is your "eyes" into your car's health and allows you to reset any codes that appear. There are a wide range of costs and capabilities available. This simple $90 Blue-driver model does everything I've needed so far. I like that it uses my phone as the interface, that it's so small I can keep it in the center console, and that I can use it on my wife's Acura as well. Here is the link:
Finally, learn how to use the advanced search function here. Almost everything you will encounter (and how to fix it) has already appeared here.

 

I will get better at using the advanced search. And I am going to for sure do the battery and get the scanner. Thanks you!

 

More old wifes tails......the battery will be replenished from starting in under 2 min of driving. Its idling in traffic with loads turned on that runs the battery down as alternator output is below 10 A. The alternator may supply 100A at road speeds for loads but only about 15A to charge the battery and only to 14.4v

 

Respectfully, there appear to be is a lot of presumptions in your assumptions here.

I'm not saying you are wrong, but, like the spelling of wives' tales, there is a wide spectrum of opinion on this and your 2 minutes to recharge assertion represents the low bookend of the many estimates, calculations, and, occasionally, measurements of time to recharge after starting that can be found online. Hopefully, you arrived at your figure by actual measurement.

And then there's my driving pattern. I intentionally live close to work to minimize driving. My 10 minute commute drive is never at road speed, the majority of my drive is low speed stop-and-go in-town driving that is speed limited to 30mph/50kph. The elevation profile is a 4 minute idling coast down a steep hill though town, crossing a long flat bridge over a river, and a short climb back up the other side of the river valley. My total time under power is probably less than 2 minutes.

So I will stick with what I originally wrote that my commute to work is so short that my battery wasn't fully recharging from cranking the starter.

 

To replace the energy taken out of the battery by starting is, typically, going to take between 5 and 10 miles of actual driving depending upon the car and all the other circumstances. Assuming a speed of 30 mph, that's 10 to 20 mins.

Richard

 

110A for 5 seconds is 0.15 AH ( Starters do not draw 450A when cranking thats stalled) The alternator will output 15AH in 1 hour so that means it will charge in 0.6 min call it 1 min allowing for recharge efficiency. PS 5 seconds of cranking is far too long anyway.


No I dont need to do measurements I already done them during 40 years as an auto electrician /consultant in same.

 

Please could you clarify the concept of an alternator outputting 15Ah in 1 hour?

Richard

 

Alternator will charge battery at max 15 A so in one hour will have put back 15AH

 

As all the others have said, start with battery replacement. It may have been new in 2022, but if the car sat for extended periods without a battery tender, the battery is probably shot. For whatever reason, today's batteries are not like the ones we had when we were young, batteries that lasted 8 to 10 years.

Also, a quote for $250 to replace the brake switch is not over the top. Lots of indie SoCal specialty shops charge around $200/hr. $250, including the part, sounds about right.

 

thanks all for teaching me about voltage and jags. the new battery I put in solved all the error messages. this forum is amazing.

 

I’m so grateful you all explained the special relationship these jaguars have with their batteries. I swear everything runs better (well maybe not the arthritic suspension). Even the transmission shifting is a knife through butter instead of a hesitant 1st - 2nd. I was wondering about comments in the master control monitor but the battery seems to have calmed that down too.

 

Very cool, glad to hear everything is working well.

Now get out, enjoy your Jag and post lots of pictures here so we can see that beauty in action!

 

It’s getting to warm in the valley but the hills beckon. Thanks !

 

^^ How much cooler are the Palm Springs temps in the hills vs. in the valley?

 

It can be 110 in the valley and 78-88 in the hills. “Hills” here means a climb of 7,000 feet up the mountains. It’s quick a quick 12 minutes on the tram or an hour up the winding roads

 

Don’t forget the battery tender. It needs to be connected whenever the car will not be used overnight or longer.

Your wiring and electrical connections are are least 20 years old. Resulting in resistance that did not exist when the car was new(er). The charging system alone will not keep the electrical gremlins away. It needs a helper. A battery tender from a reputable manufacturer is the answer for these cars. Many here are using a CTEK or NOCO Genesis, or even a Delran Battery Tender Plus. I’m partial to the NOCO Genesis 5. It’s moderately priced, and Amazon has sales on it periodically.

Z

 

As for the brke switch issue, i have the same problem right now.. everything seems fine for a while, then from nowhere i get the "rear light/cruisecontrol" messsage. I took my time crawling under the dash and replaced it with another switch i had laying around.. but no luck - problem back after 10-15 min drive.
I did some research and learned that the internals in the switch over the years, oxide??, changes. So even when measuring on the contacts it may seem to be ok. New ones are expensive so i have, actually today, bought new microswitches to solder in instead.

"Omron Long Hinge Lever Micro Switch, PCB Terminal, 2 A @ 12 V dc, SPDT, IP67", 3 bucks/each. - Hopefully it will solve the issue for good.