I just finished reading the Hayes manual from cover to cover and it does not have anything on Vacuum hose locations. I believe my SES light is being caused by a large vacuum leak with the Vent system but I can't figure out where the Vacuum lines are to replace them. I purchased a bunch of different hose sizes along with some connectors but the only vacuum lines I could find turned out to be the wiper fluid lines.

I can make the SES light go On any time I want by setting the Vent to Face and turning the fan on.
Set the vents back to the default Windshield & Feet, then turn off the fan and the SES light goes away.


Thanks,
Mike

 

Might get the codes scanned to see if that gives you a clue as to location.

 

already done, just says large vacuum leak as a possible cause.
https://chevroletforum.com/forum/tahoe-suburban-25/i-know-its-wrong-but-36208/