Alternator issues??

[Mattr5uk]

Once again seeing if anyone's had this issue. I'm having a problem with the dash lights (oil level oil light battery light and temp light) all coming on when idle is low. If I take it up a small amount they all go out. I know alternator is new. To be honest I havnt checked output yet being a bit lazy and asking before Ive checked anything. Just another niggling issue to sort out. I also have the temp light coming on when its just over quarter on the gauge?? Any suggestions on these please??

[gimme5]

Quick easy test switch everything on, heater on full etc,then blip pedal if headlights go brighter then you know the alternator is doing its job and the battery could be at fault, if nothing then check wiring with multi meter.

[Chunk]

Sounds like an earth problem to me if I'm honest