hello...i have a 94 z28 and i popped a code three days ago...car stumbled and ses light came on...got home drove it didn't come on...drove it shortly after, it stumbled and ses light came on...last night had battery disconnected for about an hour...drove it 40 miles today, no light...came out fifteen minutes later to go to bank, it coughed and ses light came on...stayed off on the way home from work then came on after i stopped and bought a code scanner...got home plugged in scanner and nothing so it's telling me i need to do a diagnostic circuit check...with scanner not plugged in and key in on position and not cranked ses light comes on and goes off...it just won't do anything with the scanner plugged in...my manual has disappeared and i have no clue...any help would be appreciated...

 

it only seems to do it after i drive it and it sits for a little while...drove it home from work then went in grocery store...came out car died and light came on...sounds like the fans are running differently too...they're usually not as loud...

 

Sounds like you bought one of the cheapie ($30) short-the-pins type scanners. That doesn't work on LT1's except the 1993's. You need a "real" scanner.... AutoXray, ScanMaster, Actron (but eh $150+ model, not the $30).