M2 coolant temp gauge and Oil Press

Have a Gleaner M2 that the coolant temperature gauge needle basically flatlined out of the temp range and doesn't move when turning the key on. Doesn't move at all when the combine is running either. Pulled the outside panel and all wires are connected as they should be.   Any idea if this is the sensor or the gauge?

Also, same machine, oil pressure gauge moves very little, when running at full speed it will read up to less than 1/4 across the gauge. Motor is in good shape and has good oil pressure. Would this be a sensor? Thanks in advance

Sounds like you lost the ground at the dash. Put a jumper at the dash to a good chassis ground and see if everything works properly again. If so, that's the problem. Make a permanent ground off the dash...
Steve@B&B

I tried what MACK said last night and had no movement from either gauge. I had the key on in the cab and put my test light on the coolant temp sender unit wire back on the motor and it lit up. I am assuming that means the wire back to the unit is okay? Does that mean my gauge is bad?   

For the oil sensor, I tried grounding it back on the motor and the gauge didn't move, and I tried my test light and nothing lit up on either wire. Any idea what that indicates?   Thanks.