Interstate Battery was charged fully and tested by Interstate Dealer and is 100%

Starts, runs and charges 14.8 volts across terminals.

Installed an Ammeter in series between neg terminal and neg cable.

Testing Now: 500 milliamps with all doors, hood, glove box and trunk shut. All courtesy lights checked and are off. Should be approx. 30mA correct?

There is no diff in current if I set alarm or not; and/or whether the hood is open or shut. (I thought hood had a sensor)

All fuses have been individually pulled, one at a time, no change in 500 mA draw. Two fuseboxes in engine bay; one on each door and the one in the trunk. Am I missing any?

Questions:

1.) Are there major fused main trunk lines that I can disconnect first to help narrow down the circuit with the excessive current draw? Or is it necessary to pull each fuse individually to locate source of draw.

2.) What about relays? Could they get stuck closed? Pull them also?

3.) In order to gain access the fuses in the drivers and pass side door jam, the doors must be open. I used a clamp to depress the black button. Will this fool the computer into think they are closed. Likewise for the trunk lid.

5.) I am aware that some "modules" take up to 45 minutes to go into sleep mode. Am I correct in assuming the 0.50 amp parasitic draw is much more than a module draw? If it is a module, it will power down when fused is pulled?

 

My car does have a hood sensor, get hood open message on dash (always wondered why doesn't say bonnet open).

Just pull fuse, close door, measure.

Good luck with it.

 

All fuses have been individually pulled, one at a time, no change in 500 mA draw.
>Two fuse boxes in engine bay;
>Two in the door jambs (One on each door)
>The one in the trunk. Am I missing any?

Still have a 500 mA draw. What am I missing here? Is this something to do with modules starting back up after the fuse powering it has been pull and reinserted?

 

When talking about such a small difference ie 20mA your problem could be a slightly higher resistance in one of your ground cables.

Before you start to rip the car apart I would be tempted to check each and every ground making sure they're clean and tight. At the same time it would be worth doing the same to the power cables to the various fuse boxes.

 

Are you allowing the systems to completely shut down? Takes 60 minutes.

See this guide:

 

Thanks for the pdf guide. I see for our XK8 shutdown time is 33 minutes, but only 3 min. if car is armed. Either way, I will let it set for a hour. Problem is everytime some fuses are pulled, they reset the timer for shutdown.

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I pulled Fuse #5 (DS Facia Fuse Box) a 15 Amp Body Processor fuse. The current drain dropped from 500 mAmps down to 290 mAmps.

A note on that fused circuit of the Body Processor Module says it controls the "5V logic and lamps". I'm going to follow that lead. Thanks

 

Gordo, is the key flap in the switch falling freely and making a click when you pull the key out?

Wayne

 

Yes. If I push the ignition key in, I can feel it push the "flap" and it springs back in place upon pulling the key out.

 

What are the chances it has LoJack or some other aftermarket tracker?

 

Gordo not a good situation!

Reading over your post I am not sure what direction to tell you to go. I would suggest first testing your grounding system. The way I did it was to pull the fuse for the fuel pump so it would not start then made a long lead connected to the battery ground in the trunk to the front of the car and used my volt meter to measure voltage at all the grounding points on the car when attempting to start the car. What I found was the strap connected from the body to the engine at the trans was not right so I replaced it and cleaned both connection ends at the trans and the body of the car. The goal was to be sure my voltage was less than 0.5v / 500mv and I got it down to .14v on the engine block. I will attach a link to my page about it.

I would also check your power leads from the trunk to the engine one of them is triple tapped in the on the transmission well to be sure all the connections are good and that you see no chafing.

We often take our xk8 to the beach and the salt air can play havoc with the electrical system and body and I am sure you have a similar situation on Florida.

Link to Jaguar Specs http://jagrepair.com/images/AutoRepa...%20Testing.pdf

Link to grounding checks JagRepair.com - Jaguar Repair Information Resource

I hope this helps.

 

Something I've had success with in the past with other cars is to allow the car to sleep with the doors opens so you have access to the fuse boxes. Once the car is asleep, measure the very small voltage drop (mV) across each fuse to see which circuits are active without disrupting the system.
Hope that helps.

 

The difference is almost half an amp, not 20mA.

 

The post I was referring to has since been edited but well done on reading the thread and not just jumping in.

 

I'm always happy to correct you Jim

 

The emergency key hole in the trunk also has a flap. i read a post someplace that here that if that flap is stuck open, it will drain the battery over time. One more place to check.

 

So I tried Nerobergstr's suggestion: Opened all the doors, etc.; let the car go into sleep mode, and tested mV. readings across each fuse. Again, DS #5 15Amp [Body Processor Module] was the most active at approx 45.0 mV. Everything else was zero or very close. There was one fuse in PS door panel for radio that had some activity in 02.0 mV range, but I pretty sure that is radio station presets.

I've pulled that fuse, and let the car sleep. So far we've reduced the parasitic draw from 490 mA down to 160 mA. by disconnecting the circuit on the BPM that deals w/ "5V logic and lamps".

The next step will be to get the car on the lift and check out grounding points per Gus's suggestion.

 

The current draw is now 0.40 mAmps and I am not sure how it was brought back down to the normal levels.

The ammeter is still in series [on the 10 Amp scale], so I can open and close doors and trunk, and watch the lights dim from 230 mA. back down to about 120 mA. After everything goes to sleep it is 0.40 mA.

The next step will be to reconnect battery and go through normal driving cycles. Then disconnect battery one more time and insert ammeter back into the loop. At this point all modules would have been powered back up and given the opportunity to go to sleep.

Because I am now able to reach nominal 0.40 mA level, I am pretty confident there is no 'physical issue' like a bad ground connection. Although I will attend to those items as part of a normal maintenance cycle.

I have two theories:

(A.) Something I did with pulling and replacing all the fuses and relays resulted in a better connection; or moved a wire that was previously shorting out.

(B.) The body processor module is acting up in an unpredictable fashion. I'm targeting the BPM because both the micro voltages tests and the fuse pulling test pointed to an anomaly in that module. My logic is pulling the DS Fascia #5 15 Amp fuse reset the BPM which gives up the 0.40 mA normal reading. Powering up and putting to sleep this module may confirm this.

If anyone is still following this thread, thank you. I'm meticulous in testing measures, but do not know that much about auto electronics, so I still need all the help I can get.

 

I have found that the restriking (out & in) of fuses and relays has helped many car owners. I hope this is all you needed to do.

 

Gus, I hope that is all that will be required. If you see this thread reappear at the top of our listings, our hopes have been dashed by the vagaries of Coventry.