1995 ford mustang temperature gauge problem

[CNM777]

I have a problem with my temperature gauge. When I turn on the lights, a.c, brake, roll down windows, the temperature gauge increases and will even go in the danger zone but i know it's not really overheating cause it will do this 30 seconds after the car has been turned on after hours of it being off. I've heard it may be the ground wires but can someone give me a video or something cause I've never had this problem before and I dont know about ground wires

 

[George7]

I have a problem with my temperature gauge. When I turn on the lights, a.c, brake, roll down windows, the temperature gauge increases and will even go in the danger zone but i know it's not really overheating cause it will do this 30 seconds after the car has been turned on after hours of it being off. I've heard it may be the ground wires but can someone give me a video or something cause I've never had this problem before and I dont know about ground wires

Did you ever get a reply to this ? My 91 LX 5.0 is doing the same thing but only with the temperature gauge. Any increased current from Lights, power windows, etc. causes the needle to rise. It wont drop to bottom of gauge either. I have been testing grounds and added a ground between the engine and firewall. The sensor on the intake manifold checks out also. With KOEO the needle doesn't move when sensor wire is grounded.
Not eager to remove the instrument cluster again, but can ground for instrument gauge be the problem?
Thanks.