Hi everyone, as the title states my car has been sitting for a little over 2 months and I’ve finally was able to put everything together today.

When it came time to start the battery was dead not even the dashboard lights came on, so I tried charging it up. I was able to get it up to 11.6v before attempting to start it but all that happened was the starter turned on for probably not even half a second and stopped.
So I decided to put my portable battery jumper on starter mode that can send 50amps specifically for this, but still the starter went on and off very quick. This went on for about 15 minutes.

I noticed the 10mm nuts that tighten the connections for the battery were extremely rusty when they were not like that before.

Moving forward I’m going to allow the battery try to charge overnight because it got extremely slow after 11V and if it doesn’t reach 12.6V or so I’m going to have it replaced.
But in the mean time what should I look over? I noticed some water under the battery near the fusebox, so I will check all those and I noticed some under my steering wheel by the steering rack when I did my brake switch replacement. Are there any electrical components there that might stop me from starting?

98
XJR
Anthony

 

A battery - like yours - which was down to 11V IS DEAD and it cannot be revived anymore. Try a new battery.

And reg. your other attempt putting a second portable battery in parallel:
1.) If the starter-cable is too thin, you will not get the amperage required thru there.
2.) If the starter cable has normal has normal crocodile clamps, the contact surface is not sufficient to get the reg. amperage thru there.
3.) If the dead old battery is in parallel, it would drain the power of the portable battery, and you will not have enough amperage to start either.

 

Would the starter only click once or would it rapidly click with a dead battery on these cars?

 

Cabling is the first concern, you've mentioned the corrosion on the terminal connectors, never a good thing. Check the cables themselves for corrosion, this will not only kill a battery quickly but prevent proper charging. If you have corrosion in the cable, replace the cable. A properly tended/maintained battery will not corrode anywhere. I've hounded on this in 10's of threads.

These cars are very susceptible to low voltage conditions (around 11.4v and under is no good)...here's a post to review... https://www.jaguarforums.com/forum/x...t-lock-208154/

another quick one... https://www.jaguarforums.com/forum/x...attery-113708/

From the How To at the top of forum.... https://www.jaguarforums.com/forum/x...-strap-286910/

This one goes on a bit, but it compares and reviews the AGM's, Don and Bob provide their experienced knowledge.... https://www.jaguarforums.com/forum/x...ations-240156/

 

Hi Anthony,

State of charge is only one measure of a battery's health. Cranking Amps capacity is another important criteria. Jaguars require strong, healthy batteries, and for some reason I don't fully understand, I have found that if the battery in the Jaguar is too weak, it can be difficult or impossible to jump-start the engine with a jump pack or another vehicle connected.

I agree with Peter and Highhorse that your battery is probably past its serviceable life, and I agree with Highhorse that any corrosion on the many battery connections in the vehicle can lead to poor battery charging, no-crank-no-start, cranks-but-won't start, hard-to-diagnose electrical gremlins, etc. In addition to the battery cables, other common problem points include the engine ground strap from the engine to the body, and the megafuse connections in the High Power Protection Module (HPPM) on the trunk/boot bulkhead just forward of the battery. Any looseness or corrosion at those connections can wreak havoc.

You did not tell us why the car was sitting for 2 months and what you had to put together before attempting to start it. Is it possible there are any additional clues in those missing details?

Cheers,

Don

 

Thank you for the links I was able to figure out it was the battery going bad so I’ll have that replaced but luckily I was able to start the car.
I’ll def go about the wires and see if they need replacing.
Hi don

I was able to get the car started tonight after letting the battery charge for 6 hours n have the leads disconnected, But the battery won’t hold a charge so I’ll be getting that replaced.

What sparked concern though was when I took the car around the block the gas pedal felt extremely loose and wasn’t able to pull the throttle body all the open.
I was able to see this when I turned the car off and had my friend hit the pedal.

While the throttle cable was disconnected I had hit the gas pedal while changing my brake switch, could this pose a problem?
I noticed a black stopper behind the pedal could this have anything to do with it?

 

Sounds like you need to remove that battery. Replace it with a new one. Throttle cable reset can be performed and a throttle adaptation after a 'hard reset' - which is leaving the battery off the car for 10 minutes at the least. Advise not to work on electrical systems while the battery is connected, disconnect it then do your work.

 

If your battery terminals are mouldy then it's worth checking the mega fuses too. Follow the positive lead from the battery to the front wall of the boot, near the spare wheel. There's two fuses in there, 500 & 250amp, the first supplies the starter & the other the rest of the car. They are known to corrode & give high resistance which causes issues & can eventually melt that mega fuse box from the heat.

 

Make sure to check the ground where it fastens onto the frame. Sometimes these get
loose or corroded which can make things difficult,

 

I have 11 cars that my wife and I drive.(plus another 10 'parts-cars')
Six Jaguars, three pickup trucks and a few VWs.
Not all are on insurance at the same time and I rotate some cars in and out of service.

I have BATTERY DISCONNECTS on most of the one's that sit idle for weeks at a time.

You should remove the EARTH CABLE from the battery if you do not intend to use the car for a period of time.
I just turn a knob and the battery is disconnected so it is easy to keep them from becoming discharged.

 

I went to Autozone and got a new one under warranty and it fired right up so thankfully it was just that.
I also performed the hard rest for the throttle adaption and tightened the throttle cable at the black square thing it holds onto and that definitely helped a lot.

I checked these fuses and luckily they are ok for now but I’ll definitely look into getting new ones just in case.

It felt pretty tight when I put a wrench to it so I just hit it with a brush to scrape of any old dirt or rust.

This is Exactly where I went wrong, I left the battery connected foolishly.

My final problem after all this is now my dashboard screen won’t light up.
When I first got the car started yesterday it was extremely dim but still visible, today I can’t see anything not even the miles.
Could this be a blown fuse? All the other lights work.

 

The 1998/99 XJ/XK cars have a display that is susceptible to deterioration.

One of my XJ8s has this fault.
Sometimes I can read it and other times it is so faded, it is not legible.

 

How difficult is this replacement?
I know I really don’t need it since I can read all the info from a reader but I’d still like it.

 

You can almost bet, if motorcarman has not replaced it...it is more
trouble than it's worth.

 

But check the fuses: they may be dirty/corroded or the onset of new, higher voltage may have blown them. The bulbs are fairly easy to access, but you have to very careful not to break the maple. There're threads on the forum and YouTubes to show the way. Google is your friend -- and us!

But check fuses first; cuz I think Randy hit the nail on the head. Is your alternator charging the new batter? You should see a warning (provided the fuse is working and lighting the warning) if not.