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Home >> GMC >> 1990 >> Forward Control 3.9 L >> Repair and Diagnosis >> Accessories & Equipment >> Cruise Control Systems >> Cruise Control System - Vacuum Servo >> Testing >> Preliminary Inspection >> All Models

All Models

Check fuse. See appropriate wiring diagram in the WIRING DIAGRAMS section. Check for bare, broken or disconnected wires. Check for pinched, damaged, crossed or disconnected vacuum hoses. Ensure servo and throttle linkages operate freely.