Hello all, well I got the verdict from the auto electricians as to why the battery light was coming on - the alternator - in their words "the voltage was jumping all over the place" indicating it was on the way out.

Cost of replacement (fitted) quoted at $1100 AUD. Considering this is a jag I thought that was quite a reasonable price as they anticipate about 3 hours' labour to get the job done. They tell me they will need to loosen some AC components to get at it. They are ordering the new alternator tonight and the car should be ready tomorrow afternoon (Wednesday - Australian Eastern Standard Time).

I'm glad I got this sorted before my big holiday trip down to Melbourne - I'd hate to be stuck on the side of the road due to failure. The auto electrician said they'd like me to drive for a few days after fitment of replacement to make sure everything's OK - however as I only have 1 week of holidays left I told them I'd drive it for about 50 KM after I pick it up - hopefully any anomalies will show up then. Then I'll drive to Melbourne hoping for the best. The tech said he might lose some sleep if I don't test for a few days - but I don't want to miss seeing my family so I'm willing to risk it - considering the alternator will be new I think the risk will be minimal.

 

Well, I'll stick my 2 cents in here. Auto "electricians" not familiar with Jags often mistakenly diagnose the alternator because ="the voltage was jumping all over the place" Take a read here then go forward, heed post #4 = https://www.jaguarforums.com/forum/x...oblems-206137/
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You may only need new brushes.

If you pull the alternator, you might as well check them before you go any farther.

 

The auto elec I went to came recommended by my Jag car club as a knowledgeable source on jags - so I think I can trust their diagnosis.