Repair and Diagnosis
- A L L Diagnostic Trouble Codes ( DTC )
- Relays and Modules
- Relays and Modules - Accessories and Optional Equipment
- Relays and Modules - Body and Frame
- Relays and Modules - Cooling System
- Relays and Modules - HVAC
- Relays and Modules - Instrument Panel
- Relays and Modules - Lighting and Horns
- Relays and Modules - Powertrain Management
- Relays and Modules - Steering and Suspension
- Relays and Modules - Wiper and Washer Systems
- Sensors and Switches
- Sensors and Switches - Body and Frame
- Sensors and Switches - Brakes and Traction Control
- Sensors and Switches - Cooling System
- Sensors and Switches - Cruise Control
- Sensors and Switches - Engine
- Sensors and Switches - HVAC
- Sensors and Switches - Instrument Panel
- Sensors and Switches - Lighting and Horns
- Sensors and Switches - Powertrain Management
- Sensors and Switches - Restraints and Safety Systems
- Sensors and Switches - Starting and Charging
- Sensors and Switches - Transmission and Drivetrain
- Sensors and Switches - Windows and Glass
- Sensors and Switches - Wiper and Washer Systems
- Maintenance
- Alignment
- Tune-up and Engine Performance Checks
- Drive Belt
- Filters
- Hoses
- Fluids
- Brake Bleeding
- Fuses and Circuit Breakers
- Service Reminder Indicators
- Wheels and Tires
- Application and ID
- Service Intervals
- Severe Service Defined
- Routine Service
- Normal Service
- 7500 MI or 12000 KM
- 15000 MI or 24000 KM
- 22500 MI or 36000 KM
- 30000 MI or 48000 KM
- 37500 MI or 60000 KM
- 45000 MI or 72000 KM
- 52500 MI or 84000 KM
- 60000 MI or 96000 KM
- 67500 MI or 108000 KM
- 75000 MI or 120000 KM
- 82500 MI or 132000 KM
- 90000 MI or 144000 KM
- 97500 MI or 156000 KM
- 100000 MI or 160000 KM
- 105000 MI or 168000 KM
- 112500 MI or 180000 KM
- 120000 MI or 192000 KM
- Severe Service
- 3000 MI or 4800 KM
- 6000 MI or 9600 KM
- 9000 MI or 14400 KM
- 12000 MI or 19200 KM
- 15000 MI or 24000 KM
- 18000 MI or 28800 KM
- 21000 MI or 33600 KM
- 24000 MI or 38400 KM
- 27000 MI or 43200 KM
- 30000 MI or 48000 KM
- 33000 MI or 52800 KM
- 36000 MI or 57600 KM
- 39000 MI or 62400 KM
- 42000 MI or 67200 KM
- 45000 MI or 72000 KM
- 48000 MI or 76800 KM
- 51000 MI or 81600 KM
- 54000 MI or 86400 KM
- 57000 MI or 91200 KM
- 60000 MI or 96000 KM
- 63000 MI or 100800 KM
- 66000 MI or 105600 KM
- 69000 MI or 110400 KM
- 72000 MI or 115200 KM
- 75000 MI or 120000 KM
- 78000 MI or 124800 KM
- 81000 MI or 129600 KM
- 84000 MI or 134400 KM
- 87000 MI or 139200 KM
- 90000 MI or 144000 KM
- 93000 MI or 148800 KM
- 96000 MI or 153600 KM
- 99000 MI or 158400 KM
- 100000 MI or 160000 KM
- 102000 MI or 163200 KM
- 105000 MI or 168000 KM
- 108000 MI or 172800 KM
- 111000 MI or 177600 KM
- 114000 MI or 182400 KM
- 117000 MI or 187200 KM
- 120000 MI or 192000 KM
Service and Repair
Specifications
Technical Service Bulletins
- Engine, Cooling and Exhaust
- Engine
- Compression Check
- Camshaft, Lifters and Push Rods
- Cylinder Block Assembly
- Cylinder Head Assembly
- Drive Belts, Mounts, Brackets and Accessories
- Engine Lubrication
- Intake Manifold
- Lamps and Indicators - Engine
- Seals and Gaskets
- Sensors and Switches - Engine
- Timing Components
- Tune-up and Engine Performance Checks
Locations- Service and Repair
- Specifications
- Technical Service Bulletins
- Cooling System
- Coolant
- Coolant Level Indicator Lamp
- Radiator Cooling Fan
- Engine - Coolant Temperature Sensor/Switch
- Heater Core
- Lamps and Indicators - Cooling System
- Radiator
- Radiator Cap
- Relays and Modules - Cooling System
- Sensors and Switches - Cooling System
- Temperature Gauge
- Temperature Warning Lamp/Indicator
- Thermostat
- Specifications
- Technical Service Bulletins
- Exhaust System
- Technical Service Bulletins
- Engine
- Powertrain Management
- Relays and Modules - Powertrain Management
- Sensors and Switches - Powertrain Management
- Tune-up and Engine Performance Checks
- Computers and Control Systems
- A/C Signal
- Air Temperature Sensor ( Ambient / Intake )
- Barometric Pressure Sensor
- Coolant Temperature Sensor/Switch (For Computer)
- Data Link Connector
- Electronic Spark Control Module
- Engine Control Module
- Ignition Hall Effect Sensor
- Idle Speed/Throttle Actuator - Electronic
- Idle Speed/Throttle Actuator - Mechanical
- Idle/Throttle Speed Control Unit
- Knock Sensor
- Malfunction Indicator Lamp
- Manifold Pressure/Vacuum Sensor
- Memory Calibration Unit
- Mixture Control Solenoid
- Oil Pressure Sensor
- Oxygen Sensor
- Relays and Modules - Computers and Control Systems
- Sensors and Switches - Computers and Control Systems
- Throttle Position Sensor
- Transmission Position Sensor/Switch
- Vehicle Speed Sensor
- Vehicle Speed Sensor Signal Buffer
Service Precautions- Application and ID
Description and Operation
Testing and Inspection- Initial Inspection and Diagnostic Overview
- Reading and Clearing Diagnostic Trouble Codes
- Symptom Related Diagnostic Procedures
- - A-E Charts & Related Test Procedures
- - Diagnosis By Symptom
- - Driver Complaint/Comments Charts
- - When to Use This Section
- Backfires
- Cuts Out/Misses
- Detonation/Spark Knock/Pings
- Dieseling/Run-On
- Excessive Exhaust Emissions (Odors)
- Hard to Start
- Hesitation, Sag, Stumble
- Lack of Power/Sluggish/Spongy/Stumble
- No Start - Engine Cranks OK
- Poor Fuel Economy
- Rough, Unstable, or Incorrect Idle, Stalling
- Stalls After Start - Cold
- Stalls After Start - Hot
- Surges/Chuggles
- Trouble Code Memory Loss
- - Diagnosis By Symptom - High Energy Ignition (HEI) System
- Component Tests and General Diagnostics
- Scan Tool Testing and Procedures
Adjustments
Diagrams- Technical Service Bulletins
Tools and Equipment
- Emission Control Systems
- Air Injection
- Catalytic Converter
- Early Fuel Evaporation ( EFE )
- Evaporative Emissions System
- Exhaust Gas Recirculation
- Vacuum Restrictor
- Diagrams
- Technical Service Bulletins
- Fuel Delivery and Air Induction
- Fuel Pressure
- Fuel Pressure Release
- Idle Speed
- Air Cleaner Housing
- Altitude Compensator
- Carburetor
- Accelerator Pump
- Bowl Vent Solenoid
- Carburetor Float
- Choke Pull-off
- Choke Relay
- Choke Thermostat/Heater
- Choke Unloader
- Service Precautions
- Application and ID
- Description and Operation
- Adjustments
- Service and Repair
- Diagrams
- Specifications
- Technical Service Bulletins
- Diagnostic Connector - Fuel Pump
- Fuel
- Fuel Filter
- Fuel Injector
- Fuel Pump
- Fuel Return Line
- Fuel Supply Line
- Fuel Tank
- Idle Speed/Throttle Actuator - Electronic
- Idle Speed/Throttle Actuator - Mechanical
- Idle/Throttle Speed Control Unit
- Relays and Modules - Fuel Delivery and Air Induction
- Secondary Throttle Valve
- Sensors and Switches - Fuel Delivery and Air Induction
- Throttle Body
- Throttle Position Sensor
- Turbocharger
- Service Precautions
- Description and Operation
- Adjustments
- Service and Repair
- Diagrams
- Specifications
- Technical Service Bulletins
- Ignition System
- Firing Order
- Ignition Timing
- Distributor
- Electronic Spark Control Module
- Ignition Cable
- Ignition Coil
- Ignition Control Module
- Knock Sensor
- Pick-Up Coil
- Relays and Modules - Ignition System
- Sensors and Switches - Ignition System
- Spark Plug
- Vacuum Restrictor
- Description and Operation
- Service and Repair
- Technical Service Bulletins
- Transmission Control Systems
- PROM - Programmable Read Only Memory
- Service Precautions
- Application and ID
- Diagrams
- Technical Service Bulletins
- Transmission and Drivetrain
- Actuators and Solenoids - Transmission and Drivetrain
- Automatic Transmission/Transaxle
- Actuators and Solenoids - A/T
- Band Apply Servo
- Case
- Clutch
- Differential
- Drive Chain
- Fluid - A/T
- Fluid Filter - A/T
- Fluid Line/Hose
- Fluid Pan
- Fluid Pump
- Governor
- Output Shaft
- Parking Pawl
- Seals and Gaskets
- Sensors and Switches - A/T
- Shift Interlock
- Speedometer Gear, A/T
- Sun Gear
- Throttle Valve Cable/Linkage
- Thrust Washer/Bearing
- Torque Converter
- Torque Converter Clutch
- Torque Converter Clutch Solenoid
- Transmission Cooler
- Transmission Position Sensor/Switch
- Transmission Pressure Test Port
- Valve Body
- Application and ID
- Description and Operation
- Testing and Inspection
- Symptom Related Diagnostic Procedures
- Delay In Drive and Reverse
- Fails to Shift 2-3 or Delayed 2-3 Shift
- Fails to Upshift or Delayed Upshift
- High Oil Pressure
- Low Oil Pressure
- No Drive In Drive or Intermediate Range, Lo & Reverse Ok
- No Drive In Drive Range; Intermediate, Low & Reverse Ok
- No Drive In Forward Ranges, Reverse Ok
- No Drive In Forward Ranges, Reverse Ties Up
- No Forward or Reverse In Any Range
- No Full Throttle 3-2 Downshift
- No Intermediate Range - 2nd Gear
- No Overrun Braking In LO, Reverse OK
- No Reverse, All Forward Ranges Ok
- Second Speed Start-Misses First
- Shifts 1-3, Misses Second Gear
- Shifts 2-1 at High Gear Speeds-Passing Gear
- Slips or Chatters In 1st
- Slow, Early, or Drawn Out Shifts With End Bump
- Transaxle Noisy
- 1-2 Shift Complaints
- 2-3 Shift Complaints
- Component Tests and General Diagnostics
- Symptom Related Diagnostic Procedures
- Service and Repair
- Procedures
- Removal and Replacement
- Overhaul
- - Unit Overhaul Notes
- - Disassemble
- Check Reaction Sun Gear & LO Race Endplay
- Converter Housing, Oil Pump & Reverse Clutch
- Differential & Final Drive Assembly
- Direct Clutch Assembly
- Drive Link Assembly
- Driven Sprocket Support
- Forward & Direct Clutch
- Forward Clutch Assembly
- Governor & Speedometer Gear
- Input Unit Parts
- Intermediate Band Assembly
- Intermediate Servo - Assembly and Installation
- Intermediate Servo - Disassembly and Inspection
- Lo and Reverse Clutch
- Manual Shaft
- Oil Strainer and Pan
- Output Shaft
- Reaction Gear Set
- Reverse Pipe & Parking Bracket
- Transaxle Case
- Diagrams
- Specifications
- Technical Service Bulletins
- Clutch
- Continuously Variable Transmission/Transaxle
- Differential Assembly
- Drive Axles, Bearings and Joints
- Flex Plate
- Manual Transmission/Transaxle
- Sensors and Switches - Transmission and Drivetrain
- Transfer Case
- Transmission Control Systems
- Diagrams
- Specifications
- Technical Service Bulletins
- Brakes and Traction Control
- Antilock Brakes / Traction Control Systems
- Brake Bleeding
- Brake Warning Indicator
- Disc Brake System
- Drum Brake System
- Hydraulic System
- Parking Brake System
- Power Brake Assist
- Sensors and Switches - Brakes and Traction Control
- Service Precautions
- Testing and Inspection
- Service and Repair
- Technical Service Bulletins
- Starting and Charging
- Sensors and Switches - Starting and Charging
- Battery
- Charging System
- Starting System
- Power and Ground Distribution
- Service Precautions
- Testing and Inspection
- Initial Inspection and Diagnostic Overview
- Symptom Related Diagnostic Procedures
- Component Tests and General Diagnostics
- Alternate Parasitic Draw Test
- In-Vehicle Testing - Delcotron Type CS Charging System
- Parasitic Draw Test
- System Diagnosis - Charging System - Delcotron Type SI Integral
- Checking Circuit With Voltmeter
- System Diagnosis - Hitachi
- System Diagnosis - Starter - Delco/Remy
- System Diagnosis - Starter - Mitsubishi Starter
- Diagrams
- Specifications
- Technical Service Bulletins
- Power and Ground Distribution
- Steering and Suspension
- Alignment
- Relays and Modules - Steering and Suspension
- Steering
- Front Steering Knuckle
- Power Steering
- Steering Column
- Steering Gear
- Steering Shaft
- Steering Wheel
- Service Precautions
- Technical Service Bulletins
- Suspension
- Wheels and Tires
- Technical Service Bulletins
- Heating and Air Conditioning
- Air Conditioning Switch
- Air Door
- Blower Motor
- Blower Motor Relay
- Blower Motor Resistor
- Compressor HVAC
- Compressor Clutch Diode HVAC
- Compressor Clutch Relay
- Evaporator Core
- Heater Core
- Housing Assembly HVAC
- Refrigerant
- Refrigerant Oil
- Refrigerant Pressure Sensor / Switch
- Relays and Modules - HVAC
- Sensors and Switches - HVAC
- Service Port HVAC
- Vacuum Reservoir HVAC
- Service Precautions
- Testing and Inspection
- Service and Repair
- Diagrams
- Specifications
- Technical Service Bulletins
- Restraints and Safety Systems
- Accessories and Optional Equipment
- Body and Frame
- Cruise Control
- Brake Switch (Cruise Control)
- Clutch Switch
- Cruise Control Servo
- Cruise Control Switch
- Cruise Control Vacuum Solenoid
- Sensors and Switches - Cruise Control
- Vacuum Pump
- Vacuum Vent Valve
- Vehicle Speed Sensor/Transducer - Cruise Control
- Description and Operation
- Testing and Inspection
- Adjustments
- Service and Repair
- Diagrams
- Instrument Panel, Gauges and Warning Indicators
- Ammeter Gauge
- Audible Warning Device
- Audible Warning Device Control Module
- Brake Warning Indicator
- Charge Lamp/Indicator
- Cigarette Lighter
- Clock
- Coolant Level Indicator Lamp
- Dashboard / Instrument Panel
- Dimmer Switch
- Fuel Gauge
- Fuel Gauge Sender
- Instrument Cluster / Carrier
- Key Reminder Switch
- Low Fuel Lamp/Indicator
- Maintenance Required Lamp/Indicator
- Malfunction Indicator Lamp
- Odometer
- Oil Pressure Warning Lamp/Indicator
- Parking Brake Warning Lamp
- Relays and Modules - Instrument Panel
- Sensors and Switches - Instrument Panel
- Speedometer Head
- Temperature Gauge
- Temperature Warning Lamp/Indicator
- Tire Monitoring System
- Transmission Shift Position Indicator Lamp
- Vacuum Gauge/Economy Meter
- Volt Meter Gauge
- Description and Operation
- Testing and Inspection
- Diagrams
- Technical Service Bulletins
- Lighting and Horns
- Backup Lamp
- Brake Lamp
- Brake Light Switch
- Courtesy Lamp
- Dimmer Switch
- Dome Lamp
- Fog/Driving Lamp
- Hazard Warning Lamps
- Headlamp
- Horn
- License Plate Lamp
- Map Light
- Marker Lamp
- Parking Lamp
- Relays and Modules - Lighting and Horns
- Sensors and Switches - Lighting and Horns
- Tail Lamp
- Turn Signals
- Application and ID
- Diagrams
- Technical Service Bulletins
- Windows and Glass
- Wiper and Washer Systems
- Relays and Modules - Wiper and Washer Systems
- Sensors and Switches - Wiper and Washer Systems
- Washer Fluid Level Indicator
- Windshield Washer Motor
- Wiper Blade
- Wiper Control Module
- Wiper Gear Box
- Wiper Motor
- Wiper Relay
- Wiper Switch
- Description and Operation
- Testing and Inspection
- Diagrams
- Technical Service Bulletins
- Application and ID
- Regular Production Option (RPO)
- Vehicle Identification Number (VIN)
- Description
- GM Automobile VIN Charts
- GM Light Duty & Multi-Purpose Truck VIN Charts
- 1982 Light Duty Trucks & Multi-Purpose Vehicle
- 1983 Light Duty Trucks & Multi-Purpose Vehicle
- 1984 Light Duty Trucks & Multi-Purpose Vehicle
- 1985 Light Duty Trucks & Multi-Purpose Vehicle
- 1986 Light Duty Trucks & Multi-Purpose Vehicle
- 1987 Light Duty Trucks & Multi-Purpose Vehicle
- 1988 Light Duty Trucks & Multi-Purpose Vehicle
- 1989 Light Duty Trucks & Multi-Purpose Vehicle
- 1990 Light Duty Trucks & Multi-Purpose Vehicles
- 1991 Light Duty Trucks & Multi-Purpose Vehicles
- 1992 Light Duty Trucks & Multi-Purpose Vehicles
- 1993 Light Duty Trucks & Multi-Purpose Vehicles
- 1994 Light Duty Trucks & Multi-Purpose Vehicles
- 1995 Light Duty Trucks & Multi-Purpose Vehicles
- 1996 Light Duty Trucks & Multi-Purpose Vehicles
- GM Medium & Heavy Duty Truck VIN Charts
- 1982 Medium & Heavy Duty Trucks
- 1983 Medium & Heavy Duty Trucks
- 1984 Medium & Heavy Duty Trucks
- 1985 Medium & Heavy Duty Trucks
- 1986 Medium & Heavy Duty Trucks
- 1987 Medium & Heavy Duty Trucks
- 1988 Medium & Heavy Duty Trucks
- 1989 Medium & Heavy Duty Trucks
- 1990 Medium & Heavy Duty Trucks
- 1991 Medium & Heavy Duty Trucks
- 1992 Medium & Heavy Duty Trucks
- 1993 Medium & Heavy Duty Trucks
- 1994 Medium & Heavy Duty Trucks
- 1995 Medium & Heavy Duty Trucks
- 1996 Medium & Heavy Duty Trucks
- Locations
- Component Locations
- Additional Information
- Miscellaneous Components
- A/C Clutch Diode
- A/C Compressor Clutch
- A/C Diode
- Air Diverter Valve
- Air Select Valve
- Blower Resistors
- Buffer Amplifier
- Check Valve
- Choke Heater
- Convenience Center
- Coolant Temperature Sender
- Cruise Control Resume Valve
- Cruise Control Servo
- Distributor Pulse Input Shield
- EFE Heater
- EGR Valve
- Fuel Injector
- Fuel Tank Unit
- Fuse Block
- Fusible Link A
- Fusible Link B
- Fusible Link C
- Fusible Link D
- Fusible Link E
- Fusible Link F
- Fusible Link G
- Generator Diode
- Horn Brush/Slip Ring
- Ignition Coil
- Inverter
- Multi-Function Lever
- Power Seat Transmission
- Shift Cable
- Turn Flasher
- Vacuum Pump
- Vacuum Release Valve
- Vacuum Tank
- Modules
- Motors
- Relays
- Sensors
- Solenoids
- Switches
- A/C Cut-Out Switch
- A/C High Pressure Switch
- Back-Up Lights Switch
- Booster Low Vacuum Switch
- Brake Pressure Switch
- Brake Switch
- Clutch Start Switch
- Console Shift Switch
- Coolant Temperature Fan Switch
- Coolant Temperature Switch
- Door Lock Switches
- Driver's Master Switch Assembly
- Driver's Power Seat Switch Assembly
- Early Fuel Evaporation (EFE) Switch
- EFE Switch
- Headlamp Dimmer Switch
- High Pressure Switch
- Horn Switch
- Ignition Key Warning Switch
- Ignition Switch
- Mirror Switches
- Oil Pressure Sender/Switch
- Park Brake Switch
- Park/Neutral Switch
- Pressure Cycling Switch
- Seat Belt Switch
- Trunk Release Switch
- Turn/Hazard Switch Assembly
- Window Switches
- Connector Locations
- Fuse and Fusible Link Locations
- Ground Locations
- Splice Locations
- Component Locations
- Diagrams
- Diagram Information and Instructions
- Diagnostic Aids
- Exploded Views
- Connector Views
- Electrical Diagrams
- Cell References
- Antenna
- Brake Warning Indicator
- Cruise Control
- Heated Glass Element
- Heating and Air Conditioning
- Instrument Panel, Gauges and Warning Indicators
- Lighting and Horns
- Power Locks
- Powertrain Management
- System Diagram
- Computers and Control Systems
- Emission Control Systems
- Fuel Delivery and Air Induction
- Radiator Cooling Fan Motor
- Radio, Stereo, and Compact Disc
- Seats
- Starting and Charging
- Transmission and Drivetrain
- Trunk / Liftgate Solenoid
- Windows
- Wiper and Washer Systems
- Fluid Diagrams
- Vacuum and Vapor Hose Diagrams
- Components
- Additional Information
- Miscellaneous Components
- A/C Clutch Diode
- A/C Compressor Clutch
- A/C Diode
- Air Diverter Valve
- Air Select Valve
- Blower Resistors
- Buffer Amplifier
- Check Valve
- Choke Heater
- Convenience Center
- Coolant Temperature Sender
- Cruise Control Resume Valve
- Cruise Control Servo
- Distributor Pulse Input Shield
- EFE Heater
- EGR Valve
- Fuel Injector
- Fuel Tank Unit
- Fuse Block
- Fusible Link A
- Fusible Link B
- Fusible Link C
- Fusible Link D
- Fusible Link E
- Fusible Link F
- Fusible Link G
- Generator Diode
- Horn Brush/Slip Ring
- Ignition Coil
- Inverter
- Multi-Function Lever
- Power Seat Transmission
- Shift Cable
- Turn Flasher
- Vacuum Pump
- Vacuum Release Valve
- Vacuum Tank
- Modules
- Motors
- Relays
- Sensors
- Solenoids
- Switches
- A/C Cut-Out Switch
- A/C High Pressure Switch
- Back-Up Lights Switch
- Booster Low Vacuum Switch
- Brake Pressure Switch
- Brake Switch
- Clutch Start Switch
- Console Shift Switch
- Coolant Temperature Fan Switch
- Coolant Temperature Switch
- Door Lock Switches
- Driver's Master Switch Assembly
- Driver's Power Seat Switch Assembly
- Early Fuel Evaporation (EFE) Switch
- EFE Switch
- Headlamp Dimmer Switch
- High Pressure Switch
- Horn Switch
- Ignition Key Warning Switch
- Ignition Switch
- Mirror Switches
- Oil Pressure Sender/Switch
- Park Brake Switch
- Park/Neutral Switch
- Pressure Cycling Switch
- Seat Belt Switch
- Trunk Release Switch
- Turn/Hazard Switch Assembly
- Window Switches
- Connectors
- Fuse and Fusible Links
- Grounds
- Splices
- Specifications
- Electrical Specifications
- Air Temperature Sensor ( Ambient / Intake )
- Alternator
- Barometric Pressure Sensor
- Battery
- Coolant Temperature Sensor/Switch (For Computer)
- Idle/Throttle Speed Control Unit
- Ignition Coil
- Ignition Timing
- Manifold Pressure/Vacuum Sensor
- Mixture Control Solenoid
- Pick-Up Coil, Ignition
- Throttle Position Sensor
- Voltage Regulator
- Mechanical Specifications
- Alignment
- Brake Drum
- Brake Master Cylinder
- Brake Rotor/Disc
- Distributor, Ignition
- Engine
- Firing Order
- Fuel Delivery and Air Induction
- Pick-Up Coil, Ignition
- Spark Plug
- Starting and Charging
- Transmission and Drivetrain
- Wheel Cylinder
- Wheel Stud / Lug Nut
- Pressure, Vacuum and Temperature Specifications
- Capacity Specifications
- Fluid Type Specifications
- Electrical Specifications
- Technical Service Bulletins
Diagnostic Trouble Codes