92 Sc400 Temp Gauge Pegged At Hot

[lexzilla]

I have a 92 Sc400 with 249k miles.

My problem is that my temp gauge moves up to H within the first minute I start the car. It first happened when driving and the needle seems to go up and down at will. Now parked and idling it stays at H.

The car does not appear to be overheating. There is no smoke at all. The oil looks as it should, not murky and so does the coolant.

This is what I know:

- I've taken the thermostat out and put it in boiling water and it opened. -

- I have replaced the temperature sensor with a new one.

- I have no leaks of coolant at all.

- Both the upper and lower radiator hoses are hot to the touch after warmup.

- After taking off the radiator cap, the fluid level is full.

- Turning on the heater does not appear to lower the temperature.

i searched and found that a member stated that the problem was a loose engine harness ground.

where can i find it?

thanks in advance

By the way

i switched clusters

and the other gauge didnt move at all

unhooked the sensor and the needle when back down to

cold

[cclove1]

I have this same issue, did you find a solution?