Hi there,

Recently purchased a Jaguar X300 XJR 4.0 Supercharger. It's a magnificent machine, however, it has an issue which is really doing my nut in!

When I purchased the car, and got back from the test drive, she wouldn't start! Had to call the recover guys out, who jump started it and said the battery was weak (managed to get some money knocked off though!).

Drove back 75 miles with no issues. The next evening I tried to start the car, and it was completely dead (no lights on dash, no central locking, etc). I went and purchased a brand new battery, installed it and the car was fine for a few days.

Then, I wnet to start it after a couple of days, and this time it has lights all illuminated on the dashboard, windows, wipers, etc all working. But did not have enough to fire it up. I put a jumper pack, and it started up. Took it for a drive, and it was the same case the following day. Now, the battery seems completey dead?

I have noticed when driving, that the Volts on the gauge drop to around 11ish? Also, when you floor it, the Volts seem to drop a little?

I have disconnected the positive terminal from battery whilst the car was running, and the car did NOT cut out.

I seriously doubt the battery is at fault, it seems as if there is a drain somewhere, or the alternator is at fault?

** One other point to note is that it has the common fault whereby you sometimes need to fiddle the gear selector in order to start it (I have had this before on an X300 and XJ40).

Please help me fix my poorly XJR - I miss driving it and whining up that supercharger!

Many thanks!

 

Could there be any light / electrical unit that is failing to disengage when the car turns off?

The boot lid does not close properly, i.e. it sticks up a little bits near one of the hinges. Not sure if this could be a contributing factor?

 

Put a voltmeter on the battery while it is running. Mine shows 14.1volts.
If it is down around the 11 or 12 volt mark, then it is probably an alternator problem.

 

Thanks for the reply.

Are the alternators a big job to do on these?

Any other reason why it could be getting drained?

Thanks.

 

Here's a brief write-up on battery voltages and parasitic drains. If you have a multi-meter it's fairly easy to determine if you have an excessive drain....although, if you do, finding the exact cause might be easy (such as a glove box lamp stuck on) or complex (such as tracing an actual short circuit)

Diagnosing A Car Battery That Runs Down


Cheers
DD

 

I had to call out the Green Flag again, as she wouldn't start, completely dead.

He noticed that the glovebox wasn't shutting properly. There wasn't a bulb in there, but would it still drain battery if it was open?

 

Ensure that your key will operate the boot/trunk lock before disconnecting the battery, as it opens electonically. A few threads in the forums about that problem.

 

[The boot lid does not close properly, i.e. it sticks up a little bits near one of the hinges. Not sure if this could be a contributing factor?[/quote]

Try opening the boot lid and, from the back, grabbing onto the lid with one hand on each side of the hinge and giving it a little pull toward you, this worked for me, I think the hinge point is mounted with notches for adjustment. when someone (LIKE ME) carries something too big in the boot and has to use a bungee cord to hole the trunk closed and then goes too fast over bumps, the boot hinge can go out of adjustment, leaving the back corners high.

As for the charging problem, your alternator gauge should read around 13 volts or more when driving, if its only reading 11, then its not charging nearly enough. the new battery lasted a while because it took a while to drain it. there is always some battery drain on the car even with the key out, even though miniscule. It sounds to me like you might need an alternator and a nice long charge on the battery. I bought a used one from E-Bay a while back, and it wasn't too difficult to change. Just make sure that your battery is disconnected before messing with the wiring.

 

Sunday morning June 10

To Psycisis

Hi

I had the excat problem with my 1995 XJ6 VDP and it drove me crazy. Beside the possible alternator here is what I did (I do not have an alternator proble). But I found out by freak cioncidence that all dash, console and head console lights were on after I shut of eveything in the car.
So I connected a 12 vlt bulb with a 1 foot wide to the Cigar lghter buld (need to remove the arm rset to reach the socket of that bulb.
Then I connected a jump start power pack to the battery cables to have power and I removed, one by one eac and single guse in the car. I ended up turning off that light by removing the number 1 fuse (red 5 amp) on the bottom of the left rear seat. That is the fuse for the rear fog light !
This did not cure the problem but at least I can drive the car now as the battery remains full.
I checked all the lights (=head, signal, stop and all are working)
I still have weird other electrical problems but they do not interfere (so far) the driving of the car.

Kope this helps

I think the fuse one by one is a good way to test for drainage

Claude

 

Hi
You do know that if you close your boot (or tri=unk) even with the battery dsconnectedyou can unlock it by providing 12 volt supply under the engine hood.
On each side ot the engine bay you have two fuse boxes (one on each side). next to each fuse bos hidden par a rubber cap and toward the inside of the bay you will se a13 mm nut securing a cable. Apply your positive lead there and find a good ground for the negative lead. When done just unlock your boo from your dashboard as usua. And remove carefi=ully the 12 volt leads from the engine bay.
Dependng on the size of your lead clamps the left side positive 13 mm nut and bolt are easier to reach.

Hope this helps.

Claude

1995 XJ6 VDP
1991 Audi 100

 

Thanks for all of the replies, guys.

In terms of the boot - it only works via the key hole on the boot only - the electronic boot release does not work, and has not worked since I have owned the car.

I appreciate the concerns - as I got stuck when I had a problem with my X300 Sport, and used the live points in the engine bay to give it enough charge to release the boot!

The problem is still there - not enough charge to crank the car over, and it's really bugging me now!

 

The battery is not charging. You need to check the alternator before spending time on anything else.

 

Agreed

 

If your instrument board/panel lights are on all the time the fault is likely to be in the small light module which is near the light switch. I did post something on this before.