Hello
I have a 1988 Cavalier,originally my problem was a rough idle and the cooling fan not coming on,I replaced the temp sensor for the ECM,then the fan came on even when the engine was cold,the relay

tests good,
I jumpered the A&B terminals on the ALDL connector and then turned the key to the run position and got no codes to flash not even a code 12.Both ECM fuses are good should I replace the ECM?
Thanks