My 98 3000 gt wont start

Sounds like your ground(negative) battery cable needs to be cleaned or replaced. Clean all three points of contact. On battery, on body(right behind battery) and on motor(base of trans/engine on radiator side) common issue with these cars. If all that is good then check the small wire going to starter. It had a female connector on it that if the little tabs are broke it might not be making good contact. If all that looks good check the voltage on that wire when someone turns the key to the start position. Should be 12 volts. If not 12 volts check mfi relay and ignition switch. The switch has two small screws holding the wire harness to it that at times they become loose and cause this sort of issue. Can try removing the small wire and hooking a jumper wire to the starter where it connects. Turn key to run position with car in park or neutral. Now just touch this wire to the positive side of the battery. If car turns over like it should then you either have a relay, ecu, bad wire connection in harness or ignition switch issue. If it only clicks like before then you have a battery issue or negative/positive battery cable connection issue.

When I turn the ignition it won't start. Battery is good but never changed the starter. What could the problem be?