Flat Battery????

[Hysteresis]

I have a Jaguar XF with an apparent flat Battery. I say apparent because the symptoms are exactly that, but I have jumpered the car to another car and get the same result, suggesting the problem is NOT the battery,
Any advice anyone????

 

[Burnerman]

Will the engine not crank over, is it slow to crank and do the lights dim?
Make sure the other vehicle has it's engine running, and use heavy duty jump leads.
John

 

[Hysteresis]

It tries to crank, then stops, all lights indicator lights illuminate, not too sure about the external lights, will try that tomorrow, it is dark presently.
I have used Heavy duty jump leads and just to make sure the jump leads are OK, I tried a second set, with the same result.
The car jumped from is a new car and the engine was running, there is no corrosion what so ever on any of the battery terminals, so I am stumped.
The car is of course automatic so I don't think it is towable as the Handbrake is automatic and the gearbox I think remains in 'Park' when the engine is not running. I need to read the Owners Manual on how to tow the thing.
I have had this problem before and Jumping the battery resolved it, but not this time.

 

[Burnerman]

You can try clamping the black jump lead onto your engine / bodywork if you can find somewhere substantial.....this rules out any earth connection. Maybe your starter motor is getting lazy!
Don't tow this one - the wheels have to be off the deck.
John

 

[Hysteresis]

Thanks for the advice John, An expensive Pick Up sound to on the Cards.

 

[Yafo]

You can try clamping the black jump lead onto your engine / bodywork if you can find somewhere substantial.....this rules out any earth connection. Maybe your starter motor is getting lazy!
Don't tow this one - the wheels have to be off the deck.
John

Sounds like it could be a broken/poor earth, if not the starter.

Try jumping as normal, with extra earth clamp to engine itself as suggested.

 

[Hysteresis]

Thanks John and Yafo for your help.
As with all modern cars with, in my view, unnecessary computer interference, my problem was caused by totally confusing alarm/notifications. I was confronted with 'gear box failure' and other totally inaccurate messages. Also problems associated with computer confusion when jumping to another battery source which confused the system. My analyse of the symptoms suggested that the problem was maybe not a battery fault. I talked to my local Jaguar man who advised that all the confusing messages are to be ignored and to simply put a new battery in the car as the scary messages about gear boxes were irrelevant. So splashed out on a new battery and all resolved. My concern initially was that the symptoms I was getting suggested it was not a battery issues and was something far more serious. Thankfully that was not the case.
The disturbing thing I now realise is that faced with a battery failure with the car in my garage and therefore inaccessible to recovery vehicles, the car becomes immoveable as the hand break cannot be released and the drive remains in P(park) so the car becomes stranded. In order to get the car to a garage takes specialist recovery assistance as disabling the drive and hand break takes some special intervention to be able to transport the car to a Jaguar agent.
It was never as complicated in the 60's, having said that BMC cars fell to bits in three years so problems such that I have just experienced never became relevant.
Thanks again.

 

[JohnD]

At this time of year it's usually the battery.

If you have a Silver one, badged Jag, it's probably a Varta. They last up to about ten years. It is usually enormous.

all lights indicator lights illuminate .

This is sometimes called "dashboard lights up like a Christmas Tree" and is the usual sign.

useful resource
https://www.jaguarforum.com/search.php?searchid=4934886