Hi everybody

I have a 2004 Jaguar XJ8, V8 4.2L, overall a good vehicle but I have to replaced the rear air shocks recently before checking in at the clinic I guess the air shocks issue it is not that bad of a problem when you have owned the car for 10 years that was the only issue so far.
Now I am inpatient in a clinic for 37 days in Milwaukee, Wisconsin so far it is been 31days in house already, before I checked in at this clinic a friend advised me to disconnect the battery (new , 1 week of using ) before checking in and I did but my question is if disconnected for that period of time what are my chances of be able to find it in decent working condition when I check out from here due to the fact that it has been snowing and around 45 degrees average

Thanks for your help in advance guys 😃✌️

 

A month connected is pushing it a bit.

If you disconnect the battery and it's in reasonable condition (which yours should be !) and well charged then it should last ... but you will loose your Trip A and Trip B milages and mpgs etc, and you will need to reset the radio so you will need to know the reset code !!

Alternatively you could get a CTEK battery charger; that make I know is safe to connect to the battery while it's still connected to the car (I'm sure there are others, but if they don't specifically say you can leave them connected to the car, avoid them [potentially fried electronics ).

CTEKS will also drop back to 'battery minder' mode when the battery's fully charged. Jag will sell you one with their name on it at double the price, but it's still a CTEK. I have a CTEK 3.6; it cost about £50 (GBP) and it works just fine.

 

My radio does not need a reset code. I have the premium sound alpine setup.

04 XJ8 VDP

 

A fully charged battery in good condtion with no load on it (disconnected) will discharge very very slowly, especially in cold weather. I wouldn't worry about it at all.

 

Thank you guys 👽✌️
Very helpful answers, I love this forum

 

Thank you ✌️👽✌️

 

✌️😃✌️thank you man

 

A new fully charged battery would have no problem lasting 1 month.
I left mine connected for over 6 (UK winter) months whilst on active duty and returned to a still healthy battery, car started up straight away (it wasn't the Jaguar, but a peugeot 405 mind!!).
Don't worry.

 

Firstly may I say I hope the treatment is going well.

We get many threads across the model tech forums about battery related issues. Modern Jaguars are very sensitive to battery condition. A partially discharged or failing battery can cause all kinds of curious electronics problems.

The best approach would have been to purchase a battery tender and leave it connected during your absence but removing the battery is the next best option.

As others have said, it will not suffer from storage off the vehicle for a few weeks but could benefit from a trickle charge before refitting.

The vehicle will have lost a number of settings by the time you do reconnect the battery. The Jaguar procedure to re-instate these is:

1. Start the engine and allow to idle until the engine reaches normal operating temperature.
2. Switch the engine off.
3. Restart the engine and allow to idle for approximately two minutes (this will allow the ECM to learn the idle values).
4. Apply and hold the brake pedal, select drive and allow the engine to idle for a further two minutes.
5. Drive the vehicle for approximately five miles/eight miles of varied driving to enable the ECM to complete it's learning strategy.
6. Reset the audio unit and climate control assembly to original settings.
7. Reset the door window motors.

The Radio Security Code has been mentioned. I did think this was exclusively a UK feature but we have had reports on the forum of a very few US spec vehicles having a coded radio fitted. It is extremely unlikely your vehicle will be coded but your Jaguar Dealer would be able to provide the unlock code.

Graham

 

Wow, there's even a procedure to connect the battery backup. These cars never cease to amaze me in their complexity of operation. But thanks for this information, I would have just connected up the battery and be done with it..

 

After a few hours, the onboard capacitors become discharged and the 'learned' engine management system adaptions are lost. Similarly the radio presets are lost after approximately 72 hours with no battery power.

The ECM begins with default settings when the battery is reconnected. It will adapt again just by driving but the Jaguar procedure is designed to minimise the time and distance required for this.

The idle speed often doesn't re-adapt by itself resulting in lumpy or uneven idling.

A disconnection is often done deliberately to reset the ECM to default if the adapted running is wrong.

Graham

 

Do the transmission settings reset too after a long period of disconnection?

 

NO.

Transmission adaptations are not cleared by carrying out a 'Hard Reset'. They can only be cleared with dealer diagnostics or equivalent.

This extract from the ZF HP6 Troubleshooting Guide confirms:


Members across the forums having models fitted with ZF 6-Speed transmissions aren't reporting anywhere near the problems of those with the earlier 5-Speed but this could be because the later transmissions haven't yet got as much age or miles on them.

Graham

 

Thanks GGG very valuable information ✌️😃✌️

 

Thanks again for all your advise, this is an update of how it went when I checked out from the clinic, remember this is in Wisconsin 20 degrees now and windy.
I connected the batery back -suspension was sitting low on all wheels- I recently replaced the rear air shocks for Arnott's so far so good so after 37 days with a disconnected battery I assumed that the suspension will sit low but slowly due to the disconnected battery which it worked fine but my concern now is that I have to drive to Florida and the Jag this morning was sitting low in the front the rear it's ok and I got the "car too low" message in the screen, after I drove around for 3-4 min and I parked the "car too low" warning when away , Now I do not know if the problem now are the front air shocks or the Air Suspension Compresor ,
can somebody share any advise about what it might be the problem with my front air suspension sitting low ?

Thanks 😩