i have a 95 z28 6spd. had the engine rebuilt last summer had it running then the fuel pump wnet out put a new pump in fired it up the check engine lite came on.. being a 95 ihave the obd1 system and the obd2 plug. found a scanner to do all applications... plug it in and it powers up.but says unable to communicate check dlc plug and such.all fuses good anyone have any ideas what may be up...?