I believe all the gauges are linked, so if one plays up it may cause a fault on another one. I checked all the fuses and they are ok. Yes, they probably share a common feed (and fuse) and a common earth. That earth has been known to play up. Probably best to locate it (let us know if you can't), disconnect, clean and reconnect. Then check continuity from the earth lead of one of the instruments to chassis earth. Yes i have a multimeter. But not sure what to do with it. Do i check the connections for continuity of the sender connections? I'd start by checking some background points. What's the voltage across the battery terminals at: Rest? Minimum during starting? 3,000 rpm... and how constant is it?Initial tests on the gauge: Release it from the dashboard. Identify the wires and the terminals on the back. How many are there? The wiring diagram and the wire colours will help. With it connected and the ignition on check the voltage between the power terminal and the earth terminal. The sender varies the resistance seen by the gauge. Initial test on the sender: Identify the wire(s) and terminal(s). How many are there? Disconnect the wire(s). Measure the resistance between the terminals with the engine off, at idle and at 3,000 rpm. You'll probably need to set the meter to a range of 0 to 1000 Ω.Jonathan