Like the title says. I have a '99 si cluster and the temperater needle just stays on cold. i know the needles not broken because i change cluster. everything is also plugged in. i don't know what i need to replace or not. thanks for the help in advance guys

 

have you checked the wiring to the sensor? if there's no physical signs (cut, not connected, etc.).... throw a test light on it.

 

check your engine coolant tempature sensor and see if it's sending signal. Have you checked the inside of your gauges? it could be a possible that it's not working properly.

 

Could be that your thermostat is stuck open.