My battery has been going dead periodically on my 1999 XK8 (113,000 miles) Jag. I can't link anything to it so far. The battery is good. It accured to me that if I put an ammeter in series with the plus cable and find a low current flow I could then pull fuses one-by-one until the culpret shows up. Then.... I thought there are some circuits in the car that use power all of the time and, there are some circuits that I don't want to pull the fuse on. Maybe my best bet is to identfy the circuits that must stay on, and then pull all the rest one-by-one, and watch for a reduction in current flow. Is there a better way? There must be. Maybe computer codes would help. I'm not sure what kind of problems show a code. Also..another note... when the battery goes dead. It is really cold dead. There isn't even a slight spark when a wire is touched to the terminals. I am surprised I haven't destroyed it. Oh yes, it takes 4 or 5 days for the battery to die, thats why I call it a high resistance (high ohms, low amps) load.

 

Trust me, pulling fuses is not going to hurt anything you can't re-program afterward, they're meant to be pulled and a connection interrupted for safety. I'd start with your first plan and see what that shows you...costs you nothing, and you only get to reprogram your radio, seat memory, and windows (if its a vert). BTW, there are 4 or 5 fuse box locations...so get the manual out to find where they are all located. If you're going to do this, you might as well be thorough!

May I inquire how you know the battery is good, and its not holding a charge as well as it should?

 

I have exactly the same problem on 99 VDP, changed batteries, same problem.
With the battery topped up the cranking speed is splendid, no signs of weakness....
Fuse pulling seemed to me to be the best idea...next to being lazy & letting someone else diagnose *their* car, then looking towards the same fault...

 

It takes a pretty good sized load to pull a healthy battery down to zero in a few days. 1/2 amp or more, if fully charged.

First thought would be a small light somewhere, but of course most of these we should see. But if the car wanted to be really sneaky, it might leave the trunk light on somehow when the trunk is closed. Or maybe one of the mirror lights on the sun visors?

 

Our batteries are 100 amp-hours, so if it's taking 4 days to die, you're looking at a 1 amp current drain (1 amp per hour for 96 hours). That should be pretty obvious on a multimeter. I'd just hook up the meter and pull the fuses one-by-one until you see a big drop in the current.

Keep in mind that a clamp-type ammeter can only read AC amps. Since the car is all 12 volts DC, you'll have to use a meter that allows you to run the circuit through the meter (most multimeters are like this). DON'T try to start the car with the multimeter hooked up to it. You'll be lucky if you just blow the fuse in the meter, however that much current might damage the meter before the fuse blows.

Oh, by the way, my wife and I took the Jag on a road trip through Utah last summer. It was incredible. I'd love to live out there, at least in the summertime.

 

The first question was, "how do you know the battery is good?" I took it to Autozone. I told him that I wanted him to prove it was bad, because I didn;t whant to trouble shoot this. First he charged it, then tested it. It handled really well. It is a Duralast from Autozone, and is 14 months old. My multimeter is and old fathfull. One time I did cook a ohms scale. It was easy to fix. I would like to here more about your trip to utah. If you would like to, I can get our e-mail address to you. There is one issue with this car that has the potential to give me fits. The battery only dies periodically. I will have to pay attention to catch this one. I found a good fuse puller at Lowes. They don't know they have them. They are in the bins with plastic hardware. I tied a show lace on mine so I don't loose it again. Thanks for giving me the feeling that this could work. There are a lot of fuses.

 

First of all let me wish you luck in tracing the leak.
My 99 XK8 had the same problem 3-4 daya to a dead battery. I got zero help at the dealer after being charged a diagnostic fee.
I did measure ( DC capable ampmeter, DCA is autorange 10/100A, resolution 1mA at 10A range and 10mA at 100A range)) a drain of about 300 milliamps, I was told that the normal drain should be around 30 milliamps. I also purchased a circuit ampmeter that plugs into the fuse holder and allows the fuse to be plugged into the tester. You get to measure whatever is flowing in that circuit. Device name is "Fuse Buddy Tester ES 304B". It's also worth mentioning that batteries that are drained flat may not recover their full CCA rating when recharged and can go flat in a shorter interval.
I checked several circuits including the heated O2 sensor which had been mentioned as a possible problem without resolving the problem.
I was too lazy and had too much work related travel to track the problem down and just used a charger if I didn't drive for a few days. My final resolution was to sell the 99 XK8 and replace with a 2003 XKR.
My XKR can go for weeks w/o a dead battery.

Good luck

BobF

 

Tracking down a current drain can be tricky on modern cars with all of the software controlled modules. What happens when you disconnect, and reconnect power is that sometimes the modules with activate when power is connected. They shut back down when they determine the rest of the vehicle is not powered up, but it can take some time.

This happens when you pull and reinsert a fuse, and when you disconnect and reconnect the battery. Sometimes the battery reconnecting will activate enough things to pop the ammeter fuse.

To help with this I install one of these on the battery negative cable;



Then with the switch closed, connect the ammeter across the switch. That way when you open the switch the ammeter is already completing the circuit, so the current flow is not interrupted and the modules stay asleep.

Then you can get to pulling fuses to track down the draw. Just be aware that when you reinstall them that might wake something up, and the current draw will look higher than normal until the module shuts back down.

As a bonus, if you can't track down the drain, you can leave the switch in there and easily shut the battery off when the car is not being used. Draining a battery dead more than a couple times ruins them so they will not hold a proper charge.

 

I used this forum to make a photo diary of our trip. The Utah stuff starts on page three: https://www.jaguarforums.com/forum/s...t=grand+canyon

By the way, if you haven't been to Capital Reef National Park you should really go. It is undeveloped, so don't expect much in the way of visitor centers or gift shops, but the scenery is spectacular.

 

Thanks to Andy94sc for the battery master switch idea, and Rev Sam for the vacation pictures. Well, I have procrastinated long enough. I made a list of fuses that I will save to last. They may present techincal issues I don't want to play with. I have identified 72 fuses to start with. They may take me to the "funny farm" before I get this done. Thanks all.

 

Howdy Folks:
I am in total agreement with Andy94SC and have already installed that cutoff switch. my problem is a ~75ma drain at sleep. I "carefully" disconnected the B+ to each fuse box one at a time except for the passenger side box (which was too difficult). This way saved having to pull each individual fuse until I found the box with the fuse circuit that was in question. (Although I still had to wait for it to sleep)
In my case, it is the Fascia Fuse Box Front Passenger Side, fuse #15 25amp for the passenger door control module, transit relay connector. Unless any of you know an easy fix for this, I am going to let the dealer take over instead of me going into the pass door since I have a few months left on my aftermarket warranty.

 

I finally got a baseline. At "sleep" I have a 280 ma drain. That means the battery would die in about 15 days, plus or minus. That makes Dr.D's 75 ma drain look very good. If mine where that good I would probably live with it. Folks, please don't sharp shoot my calculations as I report them, unless I have really made a gross error. I am not writing a scientific paper, I am just doing a little trouble shooting with the help of my friends.

 

I know this is a strange question, but I have to ask as I have seen this before. Do you leave the key in the ignition when it is parked? I had a car years back that the customer parked in his garage at home, he would leave the key in the ignition. With they key in the ignition the draw was app 100 mili amps & his battery would go dead. Does your alarm operate, as the XKs have had a problem with the little door on the ignition barrell not closing & the car thinks the key is in the ignition. We use to use the battery cut out switch on the older cars, Jaguar actually had a kit we installed on the 1988-2002 cars as they would go dead if left to sit for 2 weeks, if you added a phone & Lojack the draw was app 75 mili amps. This would kill the batteries in a week or so. I would not recomend a battery switch on a newer car as you will also loose all of your adaptations, such as ECU & TCM.

 

Those will be lost anyway, when the draw kills the battery.

280 mA is way too high. Do you have the wiring diagrams for you car, and are you OK reading them? I just took a quick peek, and it looks as though there is a main relay at each fuse box that powers that fuse box. You should be able to pull each of them to eliminate each fuse box and save pulling each fuse until you narrow it down.

Also, aside from the fuse boxes there is a conection straight from the battery to the starter and alternator. You might want to disconnect that too just to see. It looks like there are two Mega fuses near the battery that supply that.

 

Thanks for the new ideas. No I don't leave the key in the ignition. But I need to rethink the possibilities there. Also thanks for the starter and alternator circuit ideas. So far I have checked the luggage compartment fuses. No dice. As far as the blowing the fuse in the ammeter, I have got a routine worked out so the ammeter is not the main circuit path until the electronics have gone to sleep. My meter is an old fathful analog unit. I will be extra careful. I don't want to let the smoke out of it, as we used to say. We would tell the new guys that if they let the smoke out of a component it wouldn't work anymore. Thanks all.

 

While testing my circuits one-by-one I found something strange. The current flow not only dropped to 280 mA in a short time. It dropped one more step after 16/18 minutes. It dropped to 33 mA. I thought at first I had found the bad circuit when I pulled a fuse, and the current dropped. Putting the fuse back didn't increase the current flow back up to 280 mA. How come? Something else is going into "sleep" mode. In other words, my Jag has two levels of "sleep". Ah, it just came to me. The second step is the REM (rapid eye movement) mode. Just kidding! I don't know what is happening, but I don't care too much. As far as I'm concerned it's normal. Why did the battery keep going dead? Simple abuse of the battery while working on the car. Leaving the trunk lid open, playing the radio , etc. I have not been driving enough to charge the battery. With all of that, plus a constant low current load, the battery died, several times. Sorry about the false alarm. Thanks for the help, I learned a lot.

 

What fuse did you pull when you noticed the decrease in the current flow?

 

It was fuse no.21, (10 amp) left hand main beam headlamp. In the Engine Compartment, left side box. As I said it was just a coincidence. I can get the same result without pulling any fuses. Just wait the 16 to 18 minutes. It would be interesting to know what goes to sleep, but that could take another several hours of trouble shooting. Thanks for the interest....I can tell you have something on your mind.

 

After a brief perusing of the posts, I can offer Ford's method (and that of most OE's) of properly diagnosing a parasitic draw.

First, an analog meter is kinda so-so for accurate measurements. I understand that you have to work with what you have, so keep in mind your measurement may be a bit wide.

Process: Either use the battery disconnect shown above or simply disconnect a battery cable, placing a jumper lead from that post to the disconnected lead and also bridge with your meter's leads. Set the meter to the ammeter position. Open the hood, doors and trunk to allow access to the various fuse boxes. Don't forget to block off any switches that may turn on courtesy lamps, door, boot or bonnet/hood open warning/alarms. ALLOW 45 minutes for the majority of modules to go to sleep. Some will remain powered, no matter how long you wait. It wouldn't do much good for the remote door lock/alarm function to go to sleep, would it?

After the 45 minute mark has passed, opent the battery switch or remove the jumper lead - depending on which you used. Do not disturb anything else. Observe the reading on your meter, anything in excess of 25-30ma should be invesitigated. Generally, my experience has been that if the draw isn't below this threshold it will be a LOT higher that a few milliamps, so I wouldn't be too concerned about 33ma on an analog meter. I would be more prone to suspect a failing battery cell which would drain the other cells. The best check for that is to disconnect the battery and see if it continues to run down, disconnected, over the same period of time. Another source of battery drain is just the film that builds up on top of the battery itself. You can witness this by placing one voltmeter lead on a battery post and drag the other lead across the top of the battery. You might be amazed by how much that can drain a battery. The cure for this is to simply rinse the battery top with water, unless a large amount of grunge is present. Then clean accordingly.

 

I don`t know if there is any truth to this, but a dealer had told the prior owner of my car that leaving the auto-on headlights feature set to auto will cause a slow drain. I leave mine off now but I don`t know if it really matters...I haven`t had any battery issues tho