I have a 97 vdp. Have been experiencing parasitic draw on battery. If I don't drive it for a few days the battery is dead. Multimeter shows a constant 1.6 draw on 10a scale. When going through fuses, the draw goes away when fuse#5 in trunk fusebox - body processing unit - is pulled. Car starts and runs well, wipers and headlamps work, as do interior lights. I see the electrical diagrams via this site, but am not sure how to interpret as to how to move forward. Any leads as to where to check next to identify the problem? Thanks!

 

I had exactly the same symptoms in my 1995 XJR. When I pulled the body control module fuse, the drain stopped. After spending much time getting acquainted with the electrical system, I was still stumped. I even tried replacing the body control module with no luck.

Somewhere in one of the Jag forums, I found a reference to a sticking "key in" switch inside the ignition switch. This is a part of the ignition switch that tells the body control module when the key has been removed. If this switch sticks, the body control module can set a parasitic drain on the battery without setting off the "key in" alarm.

I squirted some "Tri Flow" brand lock lubricant into the ignition lock and worked the lock many times, both turning it and putting the key in and out. After this, I let the lock sit overnight to let the oil penetrate. The next morning the parasitic drain was gone. It hasn't returned in well over a year. Simple, easy fix and that lock should be lube periodically anyway. I would not use graphite powder since that won't flow and penetrate as well.

 

That sounds great. It would match my symptoms because everything the BPM is supposed to control seems to work fine. I'll give it a try this weekend. Thanks!

 

As I have posted before: when measuring current with the boot (trunk) open the bpm will draw a bit more current because it senses the boot (or a door) open, even if the boot (or interior) lights have timed out. You can trip the boot lid catch with a screwdriver to simulate the boot shut state to the bpm.

 

I had exactly the same symptoms in my 1995 XJR. When I pulled the body control module fuse, the drain stopped. After spending much time getting acquainted with the electrical system, I was still stumped. I even tried replacing the body control module with no luck.

Somewhere in one of the Jag forums, I found a reference to a sticking "key in" switch inside the ignition switch. This is a part of the ignition switch that tells the body control module when the key has been removed. If this switch sticks, the body control module can set a parasitic drain on the battery without setting off the "key in" alarm.

I squirted some "Tri Flow" brand lock lubricant into the ignition lock and worked the lock many times, both turning it and putting the key in and out. After this, I let the lock sit overnight to let the oil penetrate. The next morning the parasitic drain was gone. It hasn't returned in well over a year. Simple, easy fix and that lock should be lube periodically anyway. I would not use graphite powder since that won't flow and penetrate as well[/I][/I]

Thanks again. I used Liquid Wrench lock and hinge dry lube and it seemed to work. I measured a draw of 1.55 amps before using it. Unfortunately, I'm still left with a .65 amp draw so there's more work to be done - but that was a key piece!