My 86 Iroc's Tach,oil pressure and their light comes on for 10 to 20 mins.. Then goes off for 10 or so mins.. It depends on if the A/C or heat is on. They stay off longer if the heat is on. I have switched the clusters and still have the same problem. A guy told me he had this problem. After changing his heater coil the problem went away. I think it is heat related problem but where. I have pushed on and pulled on everything I can with no result. Has anyone had this problem? If so what was it? Also does anyone know where I can get a new circuit board for my gages. Any help will be greatly appreciated.