My seat backs on both the driver side and passenger side won't go forward all of a sudden. They will go back just fine, which means I now have to drive lying down! The battery is now on charge - it wasn't flat but was low. Anyone else experience this one?

Update: not to do with battery that is now fully charged. Going to post a new thread on this one.

 

This is an interesting thread.
I have had the window drop-down-and-raise-again feature in my XK8 coupe require re-learning. I just checked my battery's resting voltage, after 12 hours of the car sitting after a good run yesterday, and it reads 12.22 volts.
Is that considered "low voltage" and may have caused the window drop-down relearning requirement? (It is also possible that the previous owner may have disconnected the battery prior to my buying the car.)

 

That "window drops but doesn't come back up" problem is 100% diagnostic of an XK8 low battery in my experience of 13 years of ownership. But that doesn't mean the battery is on its way out - it may have been a while since you last gave the car a decent run. 12.2V sounds OK for a battery connected to the car - a disconnected battery should be over 12.8 if it's fully charged.

I'd keep an eye on it - if it keeps happening, time for a new battery.

As an aside, since I didn't drive my XK8 every day, I did have some battery issues. I fixed that by installing an Odyssey PC1350 AGM battery, which had much more capacity than the standard one and also seemed to hold a charge better. Wasn't cheap, but cheaper than replacing the standard battery a couple of times, and certainly much better than having to call out the AA for a jump start! Only thing needed was some washers to pack the battery clamp bolts with, because the PC1350 is not as tall as the standard one.

 

Thx so much for the thread...

Just experience

no rev matching
followed by ABS and DCS failure... However all worked again after a 40 mile trip..

I am sure that the reason for this sudden hick up is the 4 hour wax job, a job that was preformed with the doors open and lights on inside....

Bringing it by my mechanic tomorrow and have a look at the battery charge.. But still the whole ordeal freaked me out...

Thinking that it may be time to upgrade to a heavy duty battery...

PS.. car looks good though now after the polish so almost worth the hassel of getting a new battery...

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Interestingly, it's warm here now, and I have not had any of the electrical gremlins that I get in cold weather...

 

Yup, that'll do it!

One thing you may find useful, if you need to do it in future, is that it's possible to lock the car with the hatch open if you flick the lock on the hatch to the closed position. Once you do that, the car thinks it's closed, and you can use the first-stage lock that secures the doors but doesn't arm the volume sensors. That then shuts off 'convenience mode' and allows things to power down. You have to unlock the car again before closing the hatch. Obviously you need the doors open when working on the sills & door edges, but once they are done, you can lock the car and work on everything else.

 

Do you think that a 2 x 40 mile ride will recharge the battery enough? I have no possibility to use a tender ect...

 

I was told, when I had a battery issue during my first week with the car, that 45 mins of driving would be enough to "charge it up" - whether that means fully charged, I don't know. If you're planning to use the car in the next day or so, it ought to be fine.

 

I really haven't got my head around how/when/why different cars have these battery issues. Today I drove mine for the first time since last Wednesday - started fine, no gremlins. And I've opened it 2 or 3 times to get stuff out of it, which of course triggers convenience mode and extra power drain. I haven't taken it on anything more than local trips for weeks - 20 minutes drive each way, twice a week on average. And I don't use a battery maintainer (I have a solar panel, but I only use that when I go away & leave the car for a couple of weeks). So how come my battery is fine?

I can imagine that there may be a gradual depletion process that takes place because, while the car is being driven, it isn't being driven long enough to replenish the battery. So, over a few days and then a start (which sucks a lot of power), maybe you lose 10%, but the short trip you make only tops it up by 8% - now you're 2% down. Repeat for a few months, and the battery level will be low enough to give you problems.

That's just a theory; the numbers are simply for example. But I wonder if that's what happens.

 

What is your climate like?

 

Sucks.... well after my 50 mile drive, the alarms had disappeared, but all came back today.. So new battery ordered, asked my local jag dealer to supply me with the biggest one they have......

 

Typical maritime, modified by Gulf Stream and proximity to a continent. So, it seldom gets below 0˚C or above 30˚C. Right now, it's mid-to-high teens.

 

I've gotten into the habit that regardless of how often I drive my XK, even if it's daily, I always plug in the CTEK every night. I'm sure If I forget once or twice it's not the end of the world, but I have gotten used to it, like brushing my teeth before bed.

 

Me not got plug, unfortunately - you can see below where I park...

 

OK, so got my new and improved battery today. Works like a charm.... But what really worries me is what the service agent said..

The electronics of the XKR suck, and it will drain my battery within 1 year if I do not drive long trips and do not have a tender... So now I have to arrange a tender, unless I want o fork out for a new battery again in a year or two.

But huge upside... The sales rep was present and he noted that I was paying attention to a brand new F type S with the sport pack... He came around and handed me the keys and told me to have great drive.... Car was absolutely phenomenal... really liked it.. my XKR sound better and feels faster, but the F type was in the same league or better as the new 981 boxster I recently drove.....

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When I started my car last night to head home from work I was treated to the non-functioning climate display that ShadyJC reported. All the controls seemed to work just nothing showing on the screen. Turning off and on didn't fix it so I suspect that is another thing that is on the convenience mode power circuit.

After spending the night on charge I then got the missing centre dash display this morning. Switching off and on fixed that one.

I think a new battery might be required soon!

 

Just had this exact same problem (climate display went AWOL), and am getting constant disconnecting of the bluetooth phone, which is another problem noted in this thread. New battery required I suspect.

 

I still haven't changed my battery and was treated to a few more symptoms recently. The touch screen started flashing on and off when I started the car. I also got a warning that the boot I had just closed was still ajar so got out to close it. When I got back in the touch screen had stopped flashing but was now hung.

I had to stop very briefly on the way home to pick something up and when I started the car again the touch screen came back to life but a few minutes in to the journey a critical warning flashed up saying that the engine temperature sensor was not functioning.

I assumed it was battery related but decided to pull over and check. As I pulled over the warning light went off so I carried on home as I was pretty close. As I put the car in to the garage I became aware of a strange noise so wound the window down and realised the cooling fans were on full bore. I switched the engine off and looked under the bonnet but there were no signs of over heating so I plugged by wireless OBD dongle in to the diagnostic port and went for a drive. The coolant temperature was within the normal range so I assume the car puts the fans on full as a precaution if the temperature sensor stops working.

It is a shame that modern cars are so sensitive to voltage. I have had cars in my long distant past where the battery only just had enough juice to turn the engine over and would sound like it started on the last drop but once started would be fine. Apart from the electrical glitches there is no sign that my battery is on the way out.

I have tried to buy an AGM battery twice recently and was met with blank looks here in little old New Zealand.

 

You could try an Odyssey PC1350:

Odyssey Batteries NZ - Premium AGM Cranking and Deep Cycle Battery

 

I just went out for a short drive and got a red 'low coolant' warning after about 10 minutes. I was looking for somewhere to pull over, and it went off as suddenly as it came on. I stopped, plugged in an OBDC and watched the temp range as I continued my journey. No further problems. I checked the coolant level when I could and it's fine. Has to be battery.