Jump Started drove 1 block everything started going wrong engine was running fine but all instrumentation went out, ABS went out, got Tranny fault warning. God can't think of all what else, managed to get it park in a safe location.

Is this to say that the entire electrical system and components are relying on the battery eventhough the alternater is still running juice through the system or, is something else totally wrong here?

Never had a vehicle act anything near to this over a dead battery.

Help.

Black Cat

parts of the animal got it's energy directly from the battery, so even the alternator is running, some electronical proceses might fade out

checking battery is at least the cheapest process here ....

Across the model range, Jaguars are very sensitive to battery condition. Although it may still be OK to start the vehicle, once performance drops even slightly, all kinds of errors and warnings can trigger.

Unless there was another reason for the jump start such as something left on which pulled the battery down, if you're on the original battery it's time for a check and possibly replacement.

Graham

Amongst other things the battery acts like a huge capacitor.
It stabilises the alternator output which is not true DC.
If your battery is bad it may have lost most of this function so nasty voltage spikes can get into the electronics.
I fried a Toyota ECU with an over enthusiastic battery charger and one forum member had their Jag ECU fried by a jump start.
As Graham says these cars are rather (too) sensitive to the quality of their electrics.
Unless you're using a trickle charger I strongly recommend disconnecting the earth lead while charging.
If in doubt, change the battery. It is cheaper than an ECU!

When you jump started it, did you by any chance disconnect the jumpleads with both your and the donor engines running? If so that could be the root cause of your problems. The X Type handbook specifically warns of electrical damage being caused by doing this. The recommendation is not to run the donor engine at all through the whole process. Once started, idle your engine for 5 minutes then disconnect. There's also a warning not to connect the -ve lead to the receiving car -ve battery post, but to use the righthand engine mount. A similar case in UK recently self cleared the faults after about three starts and runs!! Live in hope!

Life is good guy's new battery and the Cat's Back all is well. Alternator and everything else checked out good as well.

Black Cat