The other day the alarm went off in my 2004 XJ8 for no reason. I turned the alarm off, but when I went to drive the car the windows did not work, the headlights did not work, the turn signals did not work etc. etc. Engine runs fine, A/C works.
Any Ideas? It is a 2004 XJ8, 40,000 miles and always garaged, new battery.

 

Grounds behind headlights, is a good place to start.

DO BE CAREFUL, NOT HARD TO BREAK THE STUDS OFF !!!!!!

 

bad advice.

breaking them saves you a couple seconds when removing. then drill and replace with nut and bolt

 

See here at the end :

https://www.jaguarforums.com/forum/x...faults-186637/

Greetings
Andreas

 

First of all thanks to everyone for the help and advice. I tried a procedure that I found on this forum and it worked! I have listed below what I did.

1. Disconnect negative battery cable
2. Attached the negative cable to the positive cable. I used a clip lead.
3.Turned on the ignition key for 1 minute.
4.Turned off the key and closed the doors to minimize any spark when I re-attached the negative battery cable.
5.Re-attached the negative cable
6.Started the engine and let it run or 1 minute. During this period all of a sudden the interior lights and headlights turned on.

Everything seems to work for now! Once again thank you!

 

I would surely check the earth grounds in the trunk without fail. I mean, I had a similar problem with a 2005 Chrysler 300C sedan a few years ago.

 

Oh I don't know. If it were me, I think that I would spend those couple of seconds.

 

Good morning all!
Bad news for me, after I reset the computer the car was fine for a few days, but yesterday I went to drive it and no headlights, no power windows etc. Just like before.
I tried the reset procedure that worked before, but it did not work this time.
I am going to check the two ground lugs in the trunk and clean them. They look brand new but perhaps the contact surfaces are corroded.
Any further suggestions?

 

make the ground connections behind the headlights front left and right new (do not take the aluminium but the metal screw connectors for the headlights as ground connection).

 

Thanks Countach,
I will check those grounds this weekend. This is probably a stupid question, but how do I get to them? Do I remove the headlights? Or are they under the hood?
Once again thank you for your response.
David

 

Hi David -
You open the front and see a big cover made of black plastic covering the headlights and cooling from left to right ; you open it with some screws and put it away. Below are the headlights and in the back of the headlights you see a ground connection to the frame. Left and right directly behind the headlights are two ground connections with some cables. I suppose that they will brake off in the first moment that you touch it. Than you connect these cables to the headlight mounting 4 cm benath at both sides with the steel screws. If problems call again and I will make a picture.

 

Hi Countach!
Once again thanks for your assistance! Thanksgiving has prevented me from looking at the car, but I will follow your advice this weekend.
David

 

Hi David-
Hope you had a nice thanksgiving- I am shure that it will work, so: much fun with cruising at the weekend..

 

Hi Countach!
I finally had a chance to look at the car. There are 3 ground studs behind the headlights on my car, 2 on the passenger side and 1 on the drivers side, . I removed the nuts, none of them broke fortunately, they all looked like brand new. I cleaned the terminals and reattached the wires to the ground studs and reset the computer again. No luck. Still no power windows, no headlights, no turn signals, power mirrors do not work, no interior lights, Car starts and runs fine, AC works fine, radio works.
You said I should reattach the wires to the steel screws on the headlights. Are they the slightly smaller screws that attach the headlight with an angle bracket? I will try that next.
Just an interesting note, when I attempted to reset the computer I saw a small arc when I reattached the battery cable. I removed both trunk light bulbs and measured the current between the battery cable and the battery. It measured about .8 amps. I could not find anything turned on and all the doors were closed etc.
Once again thank you for your assistance. I will try moving the grounds to the steel screws holding the headlights next.
David Hollinger

 

Hi David-
Anyhow take the steel srews of the Headlight fixation for new ground and clean all connectors before you fix it again because they build an oxygen/ corrosion layer because of the connection of several different materials. And you can not tighten it like you can do it with steel - because then it will break...
It might also be useful to have a look in the trunk. Down on the right side is the battery where + pole normally also is connected via aluminum screws to the body - if you take the cover mounting with steel screws instead of the regular aluminium connection that might also help.
happy xmas,
Andreas

 

Agree with Xalty. Using a nut and bolt instead of the factory stud or rivnut is the most reliable connection. Having electrical current flow through several connections (panel to stud to ring terminal) introduces potential for corrosion and poor connections. So, breaking a stud is actually doing yourself a favor.

These cars are among the worst in the industry WRT grounds. They are aluminum, the surface of which spontaneously oxidises to form non-conductive aluminum oxide in the presence of air. Current has to then flow through numerous panels that are riveted or bonded together, introducing further possible barriers, and then finally encountering the studs or rivnuts. None of this is an ideal environment for electricity. I would eliminate the studs and rivnuts as soon as possible.




I have not tackled the rear studs yet, but will do so soon. I think rather than removing the rears, I will bridge the three posts with 2 AWG wire and run another 2 AWG to a new location on the trunk floor, using a nut and bolt. This may lead to some ground loop issues, but at least the modules in the trunk will see good grounds.

Also, I have read that there is another ground beneath the front passenger seat.

Also, also, please check the drains under the windshield wiper shroud and all four sunroof drains. These routinely clog and lead to a lot of nightmare electrical scenarios.

Good luck!

 

Whllst Jaguar use aluminium studs and nuts on these earths, you can use steel provided it is zinc-coated, or, if you search the internet, you can find titanium bolts and nuts. The aerospace industry have no problems connecting aluminium and titanium.

 

All good advice listed above.

Use a voltmeter to read the voltage across the battery terminals. There should be a minimum of 12.6 volts with the ignition in the OFF position. Just because a battery is relatively new doesn't mean it's fully charged. The modules need at least 12.6 volts to communicate correctly so all the vehicle systems work properly.

Is the MIL on? If so, post the DTCs stored here.