I have a 1995 Lumina w/ a 3.1L. It is currently overheating. The fans are not coming on at all. They do work when hot wired, the rlays are good, fuses are good. wiring is good, and temp sensor seems to be accurate (according to the scan tool) there is power to the relays but seems to be no input from the ECM. There are no trouble codes. It is an OBD 1 system. where else should I look?