Hi 

New member and already a problem

My X type estate 2.2 diesel 56 plate drives well until the headlights come on , then I get DSC fault comes up on the dash followed by loss of rev counter and speedo then every other warning light on the dash comes on plus the heater comes on full and won’t turn off , any help would be greatly appreciated as in this heatwave it’s not good

Check the ground points around the engine bay making sure they are clean and tight.

Thanks for the advice, I recently had the main battery cables replaced at an independent jag specialist on their recommendation that they were brittle so maybe as you say the earths need tightening 

Certainly a good place to start Gary.😊