Why do my mitsubishi mirage gauges work only when its cool?

I have a 97 mitsubishi mirage whose gauges work (fuel temp speedo and tach) only when they want and more specifically when the temp is cool (notengine temp) first thingin the morn for about 15 min. I have checked the gauges and the fuses and the internet and others have te same problem yet no one posts an answer please help|||that's cause by a ground wire on those,i a have repaired a few of them,when its cool the wire draws moisture and this makes it work for a short time,then they go back to not working,that's a common problem with those cars,i had one and sold it,i bought it because it was doing that ,you can get them really cheap when people don't know whats wrong with them,the ground wire your looking for is located in under the dash it is what grounds the instrument panel,good luck with it.