x5 4.8 failsafe problems

[v8 racing]

Hi guys i have a 4.8 x5 59000 miles, a week ago the trans fail safe came on, i stopped the car turned off re started and it has been fine all week untill today, this morning it came back on and then cut out when i backed off the throttle, it now showing trans failsafe and engine fail safe, car is stalling when you stop, whilst trying to drive it is trying to cut out, the battery light comes on as well as the oil light, when it re fires you can hear the engine pinking, i am guessing it is a bad conection somewhere but where?? ps checked battery voltage in the boot whilst it is running and it is 14.2, any help would be very much appreciated! thanks Rob