Turn engine off. Disconnect vacuum supply (small) hose from servo. Connect hand-held vacuum pump to vacuum supply hose fitting on servo. Apply 10-15 in. Hg to servo. If vacuum holds, go to SERVO VENT VALVE CHECK. If vacuum does not hold, or if vacuum decreases in less than 10 seconds, replace servo (in a good servo, vacuum will decrease in more than 30 seconds).
Home/GMC/Jimmy Typhoon/GMC Jimmy Typhoon (1992-1993)/Repair manual/Cruise Control Systems/Servo Vacuum Valve Check
Contents
Section: Cruise Control Systems- Description & Operation
- Description
- Cruise Control Module
- Cruise Control Switch
- Set/coast
- Resume/accel
- Servo Assembly
- Astro, Bravada, Safari, Sonoma, Syclone, Typhoon & "s" & "t" Series Blazer, Jimmy & Pickup
- Suburban, Van & "r" & "v" Series Blazer, Jimmy & Pickup
- Lumina Apv, Silhouette & Trans Sport
- Brake & Clutch Release Switch/valve
- Brake & Clutch Release Switch/valve Adjustment
- Astro, Safari, Sonoma, Syclone, Typhoon & "s" & "t" Series Blazer, Jimmy & Pickup
- Bravada
- Cruise Control Does Not Engage
- Drac (speed Sensor Buffer) Inoperative
- Cruise Control Does Not Disengage Using Brake Pedal
- Speed Sensor & Buffer
- Source Vacuum Check
- Servo Vacuum Valve Check
- Servo Vent Valve Check
- Brake Release Valve Test
- Wiring Diagrams
- Abbreviations
- Accessory Drive Belts
- Adjustments
- Anti-Lock/traction Control
- Application
- Automatic Trans
- Auxiliary Emission Control Systems
- Basic Trouble Shooting
- Brakes
- Charging System
- Check Lists
- Clutches Manual & Hydraulic
- Computer Relearn
- Cooling System (mechanical)
- Cruise Control Systems
- Diagnostic Connector Locations
- Differentials & Drive Axles
- Door Locks & Anti-Theft Systems
- Driveline/axles
- Driveshaft & Universal Joints
- Electrical
- Electrical Component Locations
- Electronic Suspension
- Emission Applications
- Engine
- Engine Performance
- Fuses & Circuit Breakers
- Gauges & Instrument Panels
- General Servicing - All Makes
- Heated Glass/defoggers
- Heater
- Identification
- Manual & Power Steering
- Manual HVAC System
- Manual Trans
- MAP Guidelines
- Mechanical
- Mechanical - Hydraulic
- Metric Conversions
- Mirrors
- Pin Voltage Charts
- Procedures
- Removal & Installation
- Reset Procedures
- Rpo Codes
- Sensor Range Charts
- Specifications
- Starter
- Steering
- Steering Column
- Steering Column Switches
- Steering Gear
- Suspension Front
- Suspension Rear
- Testing & Diagnostics
- Theory & Operation
- Traction Control Disable
- Transfer Case
- Transmission
- Wheel Alignment
- Windows
- Wiper/washer Systems
- Wiring Diagrams - Engine Performance