Just starting to get my 1993 XJ140 back onto the road after being laid up for some time. Car seems to be working fine but has a battery drain. When I turn off the ignition I can hear a continuos whirring noise seemingly coming from (behind) the instrument panel which may be indicative of the cause of the problem. Before trying some of the detection methods posted on this forum, thought I would ask if anyone could explain this noise and indicate whether it might be the source of the battery leak

Thanks

 

Hello,
Mine makes a whirring noise sometimes when I step on the brake pedal while its running. I mention this for location, not timing. It sounds like its coming from up behind the dash. It seems to be related to the ABS system as that light flashes at the same time. I have never looked too closely into it because the car operates normally, and the ABS units that Ive seen are expensive. Maybe check that relay, or perhaps the ABS unit itself? Hope this helps some, Good Luck. Jerry

 

Thanks Jerry. Will follow-up.

 

If you have a multimeter, you might try placing it on the negative side of the battery to check the amp rating. Anything in the 25 - 50 range would indicate a draw (make sure the car has been sitting for some time to make sure everything that should shut down has done so). From there you can just start pulling fuses to see if one brings the amp rating down to find the problem. Not a guaranteed fix and a little time consuming but it might be worth a shot.

 

dtrain,
I too am having a battery drain issue that just started two days ago. The car wouldn't start this morning until I jumped it with my wife's van. Then after work, it needed another jump. When running, she is showing 13.5 amps on the ammeter, so I know it's charging.
I do a lot of my own work, but my electrical skills are pitiful. When you say put the multimeter on the negative side of the battery, are you saying to touch one probe to the negative side and the other to ground?
Robert

 

Robert,

If you clip the ammeter to the negative cable on the battery when the car is off (and has been off for short period of time - some components don't shut off right away), you can see if there is a draw on the battery when nothing should really be showing up. Sure the clock and similar will be pulling on the battery but if the draw is more significant, say 25 or more, it would indicate that there is a problem. You would have to start pulling fuses/relays one at a time until the draw dropped down significantly. If that happens, that's usually the problem. Sometimes it's been a light and other times a bad relay for me but I have been successful in fixing this problem three times using this approach.

Hope this helps.

 

Robert,

Sounds like you're looking for a parasitic drain. Place one probe on the disconnected negative cable, the other on the negative post of the battery. If you have a significant draw, you'll need to figure out a way of holding the probes in place on the cable & post, I've used mini-clamps and wire ties.

I think you're at-rest amp draw will be higher than was previously referenced, I have an '89 and my draw is around 40ma at-rest. If you're above 40, then you need to start looking for the parasite.......

Read the following post for more detailed info:

https://www.jaguarforums.com/forum/x...88-xj40-95459/

BTW, while your doing the preliminary reading, while your meter is connected between the negative cable and post, open and close the car door so you can see how the reading is affected by an applied draw (door handle, courtesy light) and then monitor how long is takes to settle down to the at-rest reading.

Be sure to read the above referenced post, Good luck.

 

Robert
I have not yet had the time to deal with my battery issue -- have been busy with other problems with the car!! -- but will get around to it fairly soon. If, in the mean time, you resolve your problem, I would really appreciate it if you could post how you did it.
On revisiting the site I see I omitted to thank the members who had responded to my original post. I apologize for this oversight. I do, course, greatly appreciate the generosity of those who take the time to help the technically challenged wannabe mechanics like me!!!

 

testing for battery drain/parasitic draw, is pretty simple once you know how to do it and have done it a couple of times. as its an early car, the first place i would look, if it has one, is any aftermarket alarm thats fitted. old alarms from the time, were a nightmare for drawing to much current.
interior lights are the next favorite, but normally boot/trunk lights and/or glovebox lights.

when you get 20 mins spare, have a watch of this to give you some guidance;


a good guide here also;

How to Find and Stop Car Battery Drains – DIY Car Battery Drain - Popular Mechanics

 

Although I have tagged onto 3jags thread, a lot of good info has been provided and I would like to thank all who have contributed. I haven't had a chance to check for parasitic drain, but the past two mornings, the car has started up just fine and hasn't needed a jump. And that has me frustrated! I intend to use some of the techniques suggested when I can find the time, but now I'm wondering if I didn't have something stuck in the on position. More to follow soon.

 

Well, I think I found the cause of my parasitic drain. The new passive restraint that was recently installed has stopped working. I noticed it yesterday and pulled the fuse. This morning when I got in the car to start her up, the interior lights seemed brighter and the engine started right up. I had tried to do the check with the multimeter, but I don't think I had the multimeter set up right.

 

It's worth mastering measuring current drain just so you can prove your theory.
Rob has spelled out what to do.
First, though, make sure your meter has an amps range.
If it has switch the selector to Amps.
You will need to plug the +ve meter lead into the special socket on the meter marked something like 10A.
YOU MUST PUT THE LEAD BACK where it was as soon as you have finished or you risk blowing up your meter if you try to measure volts on the current range.
Then just disconnect the ground lead from the battery, connect meter -ve to the battery -ve post and meter +ve to the free ground lead. That means all the current (amps) the car takes has to go through the meter. Don't forget (obviously) to disable the boot light switch !

 

Another trick to decide whether it is safe to use the milliamp range is to insert a test light inline to the circuit. If the bulb glows the circuit needs testing with a high amp range first.