Hi, I have an XJ8 3,2 1999
I turn on the car and I see that the instruments light blink
after 100mt I receive the message "gearbox fault" and the gerabox set to "home" mode. A minute and the instruments light off, Stability crontrol allarm, airbag light on, ABS light on.
When I stop the car I see that the most left headlapm was off, I took out to buy new one...the day after i find the battery totally off (with indicator set to change battery). I suppose the electrical problems was due to the battery. Buy a new one and when I turn on the car...again all the same message about gearbox, stability etc, instruments light off (the initial check is all ok) and this time all headlamp don't work, as don't work the emergency blinker and not work the direction lights both if i try with the emergency button and bot on single activation. The windscreen work. Appear there is a big problem on the electrical circuit, probably a short circuit. The ground cable connected to the battery become hot after few minutes. I check the headlamp bulb, the one that was off at the beginning but appear ok.
Any idea how to can solve?
I just order a obd scanner hope if this will help.

I'm worried to go to a normal workshop as I risk only to pay a lot of money for few help.
I live in London Bermondsey area.
Thanks
Mario

 

It is a electrical issue. The battery was bad so your replaced it, which is the most common reason why the warning message come on these cars. Next I would clean the wire close to the toolbox, that gets corroded. Then I would think is the alternator. But lets start from cheap and let us go our way up.

 

"the wire close to the toolbox"? Where is? The alternator, uhm can be a chance, there is a way to test it? Thanks

 

False bulkhead connector is pictured in the thread I linked below.

https://www.jaguarforums.com/forum/x.../#&gid=1&pid=1

Keep in mind the pictured car is a left hand driver.

 

Thanks, will check tomorow morning

 

Unfortnatly isnt that connector...

 

If I was you, I should do 2 things:

1. Check all power stuts, not only the false bulkhead.
There is a main one on the trunk, a black box in front of the spare wheel.
Then there are others at each fuse box.
You might want to check the alternator and start motor stud as well in the process.

2. Install a multi-meter (at the right settings) in line with your ground cable at the battery, and measure your amperes.
Then pull all fuses of a box (make a picture before, or the fuse layout is on the cover of the trunk fuse box).
You got 5 of those boxes, 2 in the engine bay, 2 under the rear seat, one on the trunk.
Slowly start to first put them back in, and watch the multi-meter.
It is a rather time consuming process, and is better done with 2 ppl, but you should see the multi-meter indicate once you put back the fuse with the big draw.

 

Thanks, will try

 

ideal Amperage ?

 

Someone may post the actual (or use Search) but after (say) 45 mins, under (say) 50mA.

 

That is correct.
If you lock the car, the amps drop to 4, then quickly to 2, then below 1Amp.
In sleeping mode after some 1/2 hr, an x308 should be at or below 30mA.

However, in your case where something dramatic is going on (incl. the hot wires), I guess all you have to check first is to find an abnormal value, it will probably hit you square in the face.
I should first check the alternator and start motor, their contacts, wires and grounds.
Hot wires can hardly be caused by a simple interior light left on.

There are several video's on Youtube on how to simply measure the Amp's, but also how to lock the car with all doors and trunk open.
You will need to do that, as 3 of the 5 fuse boxes are inside the interior, and opening any of the doors or trunk will wake up the car immediately.

 

Thanks guys, will work on it.

 

Hi Mario,

In addition to the great advice you've already received, I thought I would answer your question above. Yes, the alternator could definitely be the cause of your high current drain. If a diode in the rectifier fails, it can allow battery current to flow to ground through the alternator circuit, which creates a large drain and can lead to battery failure. Diodes are "one-way valves" for electricity, allowing current to flow in only one direction. They are used to convert the natural alternating current produced by the generator into the direct current used by the vehicle.

There is a lot of information online about testing the alternator with a volt/ohmmeter. Probably the easiest first test would be to check for AC ripple voltage at the battery. This test is more accurate when performed at the alternator terminals, but the battery is much easier to access.

Set your meter to the lowest AC voltage range, start the engine, and turn on the low-beam headlamps. Touch one meter test lead to the positive battery terminal and the other test lead to the negative battery terminal. Ideally, the meter should read 0 volts AC. Sources vary as to the maximum allowable AC ripple, but a reading over 0.5 volts AC is a strong indicator that there is a problem with one or more diodes in the alternator rectifier.

Cheers,

Don

 

Hi guys thanks for all your advice.
Now appear to work well a part the two external sidelamp (but will check sunday for fuse or why don't work, I need the car tomorrow so don't want to touch actual equilibrium)
What i do:
I measure the tension of the battery, more the 12v, I connect the cables and I burn my multimeter so I don't know the tension one connected.
I make more pressure to knob fix the ground cable to the battery and to the other group of ground cable nearby
I turn on the car and detach the ground cable to check if the alternator work properly and for 30/40 seconds, without accelerate the engine run (non normally but run) and after off.

I also connect again the ground cable and magically the car run ok and the ground cable wasn't hot.

So was the knob of the ground cable or I provocate a "shock" to the ECU resetting all things when i detach the cable while the engine run?
A mystery... remain the problem with the two side headlamp that I hope to solve sunday.
Thanks to every one, for now the situation appear good.