I was having problems with low voltage to the battery when I first got the car but a guy that does electrical work on cars remembered how all the connections in the XJS and others. get corroded after a while. I loosened and tightened as many as I could or cleaned the connectors. I used to show barely 12.6 volts at the battery. I had the alt checked and it showed very strong. At least 14.2 volts and a little over 75 amps.
After cleaning and re-tightening the cables in the engine compartment I now get 13.9 at idle. A new battery too. 14.2 when I first checked it, so I was happy. I am still only getting 13 volts on the guage though. I have taken the gauges out and hooked directly to the batter and it show the correct voltages of close to 14 volts.
Not sure if there is a ground under the dash that might need cleaning or tightening now but not sure where it might be. I did clean and tighten the grounds under the hood too. I have 3 gauges actually now. Both USA versions move up slowly to the mark. The other is out of a European model with KPH speedo. It moves up quick to the mark and quickly shows any load with A/C and lights on.
Any Ideas as to where to look for the weak link?
Thanks
Russ