GM Service Manual Online
For 1990-2009 cars only

Voltage is available at all times from the BATT2 fuse through CKT 342 (RED) to the ignition switch. When the ignition switch is held in the START position, battery voltage is applied on CKT 5 (YEL) to the park/neutral position (PNP) switch. The PNP switch supplies battery voltage through CKT 1737 (YEL) to the coil of the theft deterrent relay. At the same time, the instrument cluster grounds the theft deterrent relay control circuit, provided that the theft deterrent module sends, via Class 2 serial data line, a valid start enable password to the cluster. The theft deterrent relay coil is grounded on CKT 625 (YEL/BLK). The theft deterrent relay contacts close. Power from the BATT1 fuse is applied through CKT 142 (RED), through the relay contacts and through CKT 6 (PPL) to terminal S of the starter solenoid.