1983 Jaguar XJS volt meter reading low

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

Hi Russ, when you “took the gauges out” did you go over all the connections in the gauge cluster, as described in Kirby’s “Book”? If you did, perhaps the next step would be to install a dedicated ground wire for the cluster.(Again, in the Book) All of the gauges, and their lighting, are grounded through the printed circuit , which is not too reliable. A separate ground wire, attached to the metal cluster housing, and then to a good spot behind the cluster, might help you. I did this to my own car when I first got it, and have been happy with the results.

Thanks Dave.

I guess I missed that in the Book, maybe. Anyway such a simple fix. I did check the nuts, retightened them and looked for any cracks in the printed circuit. I can finally see the turn signals and high beam light too. This new cluster seems to be much better than the previous ones. I will put a dedicated wire on too.

Thanks

Russ