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Please help: unknown power supply unit in trunk

XK8 / XKR ( X100 ) 1996 - 2006

Please help: unknown power supply unit in trunk

 
  #1  
Old 04-17-2019, 07:52 AM
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Default Please help: unknown power consumption

Hi all,

two weeks ago I purchased a nice XKR Convertible from 2004 which should have been somewhere in the US until now.

It only had one owner and a full service record, therefore I assume this to be a "clean" example.

However: I recognized that the current consumtion when parked seems quite high. Even with a small charger attached the battery was empty some days ago.
In the trunk there's some sound of electrical operation and after some investigation I found a kind of power supply unit between the Navigation DVD Unit and the hydraulic pump which makes the noise.

Any idea what kind of unit this is?

BR
Ralf
 

Last edited by xkr_dougie; 04-17-2019 at 11:53 AM. Reason: clarification
  #2  
Old 04-17-2019, 08:44 AM
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Ralf,

Welcome to the Forum. I'm most intrigued about your USA import and look forward to hearing your experiences in Germany.

A picture would be nice to see what you're talking about. It's easily done on this forum when you make a post. Hit the red reply button, and click on Manage Attachments. Wait until the pic is 100% loaded before hitting the upload button. You should see in your draft.

I suspect you're talking about the rack, on the right hand side of the trunk, where the CD changer is on the bottom, and the hydraulic pump is on the top. Depending on the options on the car, there's was the navigation unit (that you have), plus an optional premium sound system amp. Maybe that's the problem unit.

For power drain, check the amperage across the battery cable ends, when the car is off, closed, lights out etc. If amps is greater than 100mA, you've got a drain. Way to find what is causing that out, is to start pulling plugs/fuses to see what system is causing the drain. As you suspect it's that, start with unplugging the amp.

As you're new to the strange beast that is the XK8, there's also a couple of loose power connectors in the trunk near the battery. Don't worry about those, as those were for the mysterious factory installed battery transit device .... which BTW no-one has ever seen.

Good luck.
 
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Old 04-17-2019, 08:55 AM
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Possibly an anti theft device like a Lojack?
 
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Old 04-17-2019, 09:01 AM
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Thanks for your response, David! Most appreciated.

It's the unit with the heatsink on top which makes the noise.
And I have to look for a proper way how to measure the idle current, as when the trunk lid is open the two trunk lights will falsify the measurement.

 
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Old 04-17-2019, 09:42 AM
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Isn't that just the amp for the stereo? Does it always make the noise, even when the amp hasn't been in use and is hot?
 
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Old 04-17-2019, 09:43 AM
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It is indeed the stereo amp. May need replacing?
 
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Old 04-17-2019, 09:44 AM
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It makes the noise even the Car is in the Garage for days. And I would say its warm - not hot.

Is there some info available on this unit? Maybe I can fix it when I have the connection diagram.
 
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Old 04-17-2019, 09:49 AM
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Yep. Something is buggered in the amp if it's always warm.

Check drain values (mA) then pull the unit's connectors.

As for the trunk lights, simply prise/pull the lighting plastic fascia out, and there's a connector to it that unclips. Be careful, it's old plastic and you might easily break the clips.

Then simply check if there's still a drain. By pulling the amp you should see if that stops/reduces the drain.
 
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Old 04-17-2019, 10:02 AM
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Done!

- Both Trunk Lights disconnected
- Current consumption 1,8A
- Amp disconnected -> Current consumption goes down to 0,9A

So there maybe might something which makes the amp to stay engaged and draws some current itself?

I guess the next thing would be to pull the fuse of the radio?
 
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Old 04-17-2019, 10:46 AM
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Default Are you sure thatís Right Amps units as thatís a lot!

Ralf

Are you sure thatís in Amps! Not different scale as thatís a lot of stray current.

Wouldnít worry about radio for now(as it uses minimal power with Amplifier now disconnected) as you must have a lot of systems active 100percent of the time!

Other forum owners noticed big drains if the tiny car key cover at the steering wheel doesnít close properly as car keeps all systems active. Could be worth cleaning that and trying again. Make sure you lock the car and use key to manually open the trunk, when you check the current draw
 
  #11  
Old 04-17-2019, 11:08 AM
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Unfortunately I'm quite sure about the measurement :-)

Just cleaned the key cover with brake cleaner and lubricated with some WD40 .... proper operation seems confirmed by the sounds when sticking the key in and pulling it out.
At this point in time i can open the trunk only electronically because I only have the green key. The other one is beeing sent to me the next days.
So all measurements are performed with open roof, doors closed and locked but boot lid open.




 
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Old 04-17-2019, 11:09 AM
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You can easily trip the trunk latch with a screwdriver and not have to disconnect the lights. It's also a good way to avoid locking the keys in there when working on the car.
 
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  #13  
Old 04-17-2019, 11:21 AM
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Default Thatís Half the problem fixed

Hard to check stray current if the car is still alive. Not sure how long you have to wait until car shuts down naturally when unlocked and with boot open.

Stories on this Forum is that the current draw is less when locked. Many members put their cars on a CTEK battery tender overnight/few days off. Itís a good modern intelligent battery minder/charger that detects what needs to be done all the time. These cars are so picky on battery voltage. It does also extend the life of the battery BIG time, at very little cost, so long as the car is in a secure garage.

I say close her up for now and see how it goes for next few days with the Amp disconnected.

Good of luck with the car and let us know how you get on with her
 
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Old 04-17-2019, 11:27 AM
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Just followed the tip with the trunk latch.... so car thinks all closed now and confirms with a slight chirp and a flashing indicator
With the amp still disconnected it draws ~1A .... but I will check in an hour again if this stays the same.

Is the car I have here more ore less equivalent to the xk8? I assume I will need the proper wiring diagramm sooner or later. :-)

As this car is a bit new to me, I don't know what conditions would prevent the car from going into sleep mode.
 
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Old 04-17-2019, 11:54 AM
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Default Your 2004 Gen3 XKR is .... well... better than my 1999 XK8

All X100 models are on same platform but you have picked a beauty, where Jag leant and dealt with problems from the previous two generations. Plus with your 4.2L V8 you wonít be lacing for power.

Iíve had my car for a year and am still learning some of the quirks.

No idea how/when the car will go to sleep. May be a while/may be10 min/ maybe never with boot open.

Chill and enjoy the beautiful car. Itís a problem which with care, youíll solve eventually. Just get a decent modern battery minder and youíre half way there
 
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Old 04-17-2019, 12:05 PM
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You all are a fantastic help, David!
Makes me not feel alone in the dark.

As plugs & cables are among my best developed skills, I'm still optimistic to find the reason for this. Might only take a while...
 
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Old 04-17-2019, 12:50 PM
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Default Good with plugs and cable... how about a soldering iron?

I must admit Iím better with spanners and wrenches 🔧 but this car has the multi-connectivity between computerised control modules which throw up all kinds of warnings. Invest in a OBD2 reader specific to Jaguar and youíll save a lot of time rooting out problems. Theyíre not expensive with Apps on smart phones. Some fixes will involve digging through wires.

Still, enjoy your powerful car, and with Tender Loving Care (TLC) youíll have many an enjoyable journey. I guarantee your beautiful car will turn heads and be the envy of people.

Keep in touch here and your experiences can help other members.

Google frankcís Blog on his car and have good chuckle on what he had to deal with on his life long X100 ownership.
 
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Old 04-17-2019, 12:54 PM
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I recall reading that the car will be in sleep mode after about 30 min, and should draw around 30 ma. With the trunk latch closed and doors locked you should see the red light on the gear selection console flash occasionally. I don't think the windows need to be up, but not certain. It's been a while since I've gone through this exercise.
 
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Old 04-17-2019, 01:09 PM
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....what should I say? :-) The minimum what people expect from me as an electrical engineer is, that I can explain where all those electrones have gone to, when the battery is empty the next day.

The red ligth next to the gear selector is flashing slowly and the current consumption is down to about 0,7A

When I plug in the plugs into the amp unit, it immediately starts up and makes the well known noise.
A typical car amplifier has an remote imput coming from the radio which tells him to switch on.

Does a schematic of this part exist? Would like to measure the voltage of this remote line, if it exists.
 
  #20  
Old 04-17-2019, 01:27 PM
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Default Hehe! A German electrical engineer with a sense of humour

Ralf,

You, an electrical engineer, and the XKR will have fun together. Why I enjoy the 1999 XK8 is because I can tinker with it in the garage. Thereís always something to be done.

The car came with either a HK or Alpine premium music Amp system so not sure what you have.

Due to age, old capacitors etc, probably worth just replacing the unit, but youíll know more than me. However with your Amp reading, you probably have stray current too somewhere else.
 

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