Join Date: Mar 2002
Location: Austin, TX, USA
Its been a few hours since you posted so let me give this a stab. In short I don't know if a scan tool will turn the fan on or not. I do know that most likely depends on the scan tool. The 3rd gen camaros could energize the fans via the diagnostic terminal. I would presume that 91s would also. It's just that some scan tools are only good for reading codes and a few parameters. Others will let you enter factory diagnostic modes and all sorts of stuff. I'd start troubleshooting by getting a schematic and tracing through the fan circiutry.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI