GM Service Manual Online
For 1990-2009 cars only

The self check used by the control module monitors the voltage on the KS circuit and if the voltage is below about 0.4 or over about 4.6, a DTC P0327 sets.

Knock Sensor (KS) DTCs: DTC P0327

A DTC set when system is in a self check, and voltage on the KS circuit is above or below the specified range. Refer to the applicable table.