Well as is so common I am experiencing auto transmission issues.
2002 Xtype 3.o with 89k miles.

The car has been driving fine, no issues but returning home the other day the car violently shook while coasting down a hill at approx 55mph, I was off the gas peddle just coasting, no fault code or light. After looking over the car I proceeded and 5 minutes later it did it again, "transmission fault) light lit up.
No limp mode etc. Got the car home (flat bed) went thru fluid drain and fill procedure, refilled. Re-scanned no code other than P1000.

Test drove did well until 35 minutes into drive, it shook again, light came on. Another flat bed to home and I noticed that after I powered up at home the transmission fault light was out, scan shows only a P1000. The car will start, drive, shift smoothly again.

Some recommend clearing ECU by disconnecting and touching the two candles together.......What does this do?

Any thoughts?

As I read thru countless forums I cam across the below old post. Does this hold any merit? Indicating an electrical source to this gent isssues (mind you I never went into limp mode).

Any help would be appreciated.
OLD POST>>>>>>
"Hi,
I had the same problem on my 2002 Jaguar x-Type 2.5V6 here in England, and I was getting told that I had to replace the gearbox and it was going to cost £1000's to do.

Through some research I found out for my relief it was none of these things:-

First of all you got to do the following it takes a couple of hours to do, but you can do it at home with no special tools.

Right here goes:-
Disconnect the battery
Get to the fuse box behind the Passenger side dash board - you need to pull fuse no 67 out
Right now here goes the fun part you've got to do some disassembly work:
Take the front left hand side wheel off it may be your right front wheel off in America
Take the inner black wheel arch out probably 8 nuts and screws if I can remember
Underneath you'll find the Alarm Immobiliser Alarm Sounder - Disconnect this - it doesn't effect the alarm system
put the front wheel arch back together and put the wheels back on
Under the bonnet take out relay 3 and 8 it's the automatic gearbox and horn relay and swap these over
Put a new 5amp fuse in fuse 67
Leave the battery disconnected for a couple of hours overnight it GOOD
Then reconnect the battery and go and start the car and hey presto gearbox fault fixed.
I found out that it was the Alarm Sounder that was shorting out as it's basically a rechargable battery that eventually corodes and short circuits and car goes into LIMP mode.

Hope this helps you I did mine before Christmas 2011 and I use the car everyday with no further problems what so ever. So this is worth ago before you get Jaguar involved.

Thanks

Paul"