How do you test a alternator on an xk8 any ideas! On old battery car start runs than goes dead and error codes come up abs stabilitt and gearbox fault pretty lights but no help! Have ordered new battery but wondered if i check alternator

 

The best way is to take the car to an AutoZone, Advance Auto or Sears and have them do a test on the battery and the electrical system. FYI you will get a host of errors when the battery goes dead. This car does not like a weak batteries...