Before I start, it's not the battery,that's new and showing at least 12.8 volts standing.
Now the poser. When I start the engine all the dash lights go out and the fuel gauge works. The windows,wipers,temperature gauge EPB release,rev counter,reversing dipping mirror and climate don't work.In fact if I open the climate screen it says "Ignition off"although it's not as the engine is running.After 10 seconds or so,everything starts working and is ok.till I turn off the ignition and away we go again This also happens if I just turn on the ignition and not the engine.
Any Ideas guys?

 

Just because a battery shows 12.8v when the car is off does not mean it is healthy. I presume by your battery comment, that the battery is far from new. First and cheapest thing I would be doing with the symptoms you describe is put in a new battery. If that does not solve the problem, I would be checking the ground points around the car for corrosion.

 

I did state that the battery was new.I was just trying to avoid all the usual battery answers.

 

It sounds like you have multiple modules faulting. both the front and rear BCM, and maybe the ECM? I would start checking grounds. The behavior is pretty strange. To really dig into it you will want a pin out of the modules and expected voltage. Has there been any strange behavior before this? Did it start when you changed the battery? Or did this prompt you to change it first? Have you pulled codes at all?

 

Hi Scott,

You've already received some good advice regarding ground points. Corrosion on the ground points is very common, and since the ground studs, nuts, washers and harness wire eyelet terminals are all made of aluminum, the corrosion takes the form of a very thin layer of white aluminum oxide, which appears harmless, but is an electrical insulator that can cause all manner of difficult-to-diagnose electrical gremlins. Just note that the torque specification for the nuts is very low at 6.5 ft. lbs. / 9 Nm, which is just over hand tight. We've had many reports from owners who managed to snap a ground stud off the body by overtightening the nut.

You could also have one or more electrical connectors that are corroded, loose, or water contaminated.

Another common issue is water contamination of the electrical connector for the ECM, which is under the cabin air microfilter housing in the engine bay. There is a water drain below the connector, but it tends to become clogged with leaves, seeds and other debris, causing water to pool up around the connector and make its way into the ECM, which is mounted behind the glove box.

Personally, I would start by making a list of all the circuits that are malfunctioning, then reviewing those circuits on the wiring schematics to see if there is one common point that could affect all the circuits, such as a module, electrical connector, relay, ground point, the ignition switch, etc.

You can download the wiring schematics here:

Jaguar X350 Electrical Guide 2004

Cheers,

Don

 

That.
Plus, sorry to insist, maybe the battery.
Even "new" batteries are sometimes faulty. A cell may be damaged in your battery and the battery cannot sustain the high current draw during starting.
You may read 12.8 V before starting but it may well be that the voltage collapses for a few seconds just after starting due to the starter consumption, before the alternator follows up to establish a 14 V tension.
The electronics of the X350/358 is very sensitive to low voltage transients!

 

I changed the battery as a possibility and there are no codes showing on a Jaguar dealer scanner.As I said this problem is exactly the same if I only turn the ignition on, so there is no voltage reduction due to engine cranking and no boost from the alternator.

 

Here are the ground locations and the modules for the 04. If you had no weird issues prior to this starting then I would start here.

 

It may be instrument cluster as a lot of modules run through it on way to ECU/ECM. Jag software should show faulty modules if individually scanned. Also, an I930 scanner for yourself may be a good investment unless ya want to get a real DrewTech mongoose with used laptop with LR/JLR preloaded. This is the only way I figured out how to take dealer out of equation.

 

What about a hard reset? (disconnect the battery again for a few minutes).
Reason is, half the electronics remain powered regardless of ignition etc.