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1991 GMC Sonoma CAR/TRUCK REPAIR PROCEDURES AND DIAGRAMS - WHAT GMC REPAIR SHOPS DON'T WANT YOU TO KNOW
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- Wiring Diagrams
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- Specifications
- A/C & Heater Service
- Brake Service
- Fuel Filter Replacement
- Driveline, U-Joint & CV Axles Replacement
- Starter & Alternator Replacement
- Maintenance Lamp Reset
- Radiator & Hose Replacement
- Serpentine Belt Service

A/C & HEATER SERVICE PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
A/C & Cooling System Maintenance -> General Motors Corp. -> 1990-2002 Chevrolet & GMC S & T Series & Oldsmobile Bravada
Vehicle: 1991 GMC Sonoma 4.3 V6 GAS
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BRAKE SERVICE PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
DISC BRAKES, GENERAL MOTORS -> Bendix Single Piston Sliding Caliper -> CALIPER SERVICE -> ASSEMBLE -> DISASSEMBLE -> INSTALLATION -> REMOVAL
Vehicle: 1991 GMC Sonoma 2.5 L4 GAS
REMOVAL
- Siphon two-thirds of brake fluid from master cylinder reservoir serving front disc brakes.
- Raise vehicle, support on jack stands and remove front wheels.
- Bottom the caliper piston in bore. Insert a screwdriver between inboard shoe and piston, then pry piston back into bore. The piston can also be bottomed in the bore with a large C-clamp, Fig. .
- Remove support key retaining screw.
- Drive caliper support key and spring from steering knuckle with a suitable drift and hammer, Fig. .
- Lift caliper from anchor plate and off rotor, Fig. . Hang caliper from coil spring with wire. Do n...
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FUEL FILTER REPLACEMENT PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
General Motors Corp./Saturn Light Trucks, SUVs & Vans -> Fuel Pressure Relief -> Except Montana SV6, Relay, Rendezvous w/3.6L Engine, Terraza, Tracker & Uplander -> Engine Fuel Pressure Service Port -> Engines Less Fuel Pressure Service Port
Vehicle: 1991 GMC Sonoma 4.3 V6 GAS
Do not smoke or allow an open flame of any type when working on or near any fuel system related components. The highly flammable vapor mixtures may ignite, resulting in serious personal injury.
Prior to disconnecting fuel lines, the fuel system pressure must be relieved to prevent accidental spray of fuel.
After the battery has been disconnected and reconnected, some abnormal driveability symptoms may occur. The vehicle may need to be driven while the vehicle relearns its adaptive strategy.
Engines Less Fuel Pressure ...
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DRIVELINE, U-JOINT & CV AXLES REPLACEMENT PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
CV AXLE SHAFT, Replace
Vehicle: 1991 GMC Sonoma 2.5 L4 GAS
- Disconnect battery ground cable.
- Unlock steering column, then raise and support vehicle.
- Remove wheel assembly, then axle nut and washer.
- Support lower control arm, then remove lower shock absorber nut and bolt.
- Scribe all revolving driveshaft components in relation to connecting component to ensure correct balance upon assembly.
- Insert drift through opening in top of caliper into rotor cooler vanes to keep axle ...
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STARTER & ALTERNATOR REPLACEMENT PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
Starter, Replace
Vehicle: 1991 GMC Sonoma 2.8 V6 GAS
Upon removal of starter, note if any shims are used. If shims are used, they should be installed in their original locations. After installation, if starter is noisy during cranking, remove one .015 inch double shim or add one .015 inch single shim to outer bolt. If starter makes a high pitched whine after firing, add .015 inch double shims until noise ceases.
- Disconnect battery ground cable.
- Raise and support front of vehicle.
- Raise vehicle half way to gain access to starter motor.
- Re...
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MAINTENANCE LAMP RESET PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
General Motors Corp./Saturn Trucks -> Traction Control System (TCS)/Electronic Stability Control (ESC) Warning Lamp ->
Vehicle: 1991 GMC Sonoma 2.8 V6 GAS
This lamp should light for a approximately 6-8 seconds when the ignition is turned On as a bulb check. If t...
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RADIATOR & HOSE REPLACEMENT PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
Radiator, Replace
Vehicle: 1991 GMC Sonoma 4.3 V6 GAS
- Drain cooling system into a suitable container.
- Remove overflow hose.
- Remove upper fan shroud.
- Remove radiator hose inlet.
- Remove radiator hose outlet.
- Remove heater outlet hose.
- Remove transmission oil cooler lines.
- Remove engine oil cooler lines.
- Remove two radiator mounting bolts.
- Remove radiator f...
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SERPENTINE BELT SERVICE PROCEDURES FOR 1991 GMC Sonoma AUTOMOBILES
Serpentine Drive Belt, Replace
Vehicle: 1991 GMC Sonoma 4.3 V6 GAS
- Remove belt tensioner pulley retaining bolt...
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COMPONENT LOCATION DIAGRAMS FOR 1991 GMC Sonoma AUTOMOBILES
Component location diagrams for most 1991 GMC Sonoma cars and light trucks sold in the U.S. from 1990+.
![]() Components on diagram: |
![]() Components on diagram: |
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WIRING DIAGRAMS FOR 1991 GMC Sonoma AUTOMOBILES
OEM drawn wiring diagrams for most 1991 GMC Sonoma cars and light trucks sold in the U.S.
![]() Components on diagram: |
![]() Components on diagram: |
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TECHNICAL SERVICE BULLETINS FOR 1991 GMC Sonoma AUTOMOBILES
OEM TSB listings for most 1991 GMC Sonoma cars and light trucks sold in the U.S. from 1985+.
Document: Car and Truck Fix It Right the First Time Issues Vehicle: 1991 GMC Sonoma 2.5 L4 GAS Auto Systems: |
Document: GM TIRE WARRANTY PROGRAM CLAIMS GOODWILL GUIDELINES - REVISED Vehicle: 1991 GMC Sonoma 2.5 L4 GAS Auto Systems: |
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COMPONENT/PARTS SPECIFICATIONS FOR 1991 GMC Sonoma AUTOMOBILES
BRAKE SPECIFICATIONS: Brake drum, rotor, caliper, and related specifications for most 1991 GMC Sonoma cars and light trucks sold in the U.S. and Canada from 1970+.
- Brake caliper mounting bolt torque
- Brake drum runout, machining, & discard specs
- Minimum brake lining thickness.
- Brake rotor runout, parallelism, machining, discard, & finish specs
A/C SYSTEM SPECIFICATIONS: Air conditioning refrigerant capacity and type as well as lubricant capacity for most 1991 GMC Sonoma cars and light trucks sold in the U.S. and Canada from 1980+.
- Refrigerant capacity & type, compressor oil viscosity, total system oil capacity & compressor clutch gap
COOLING SYSTEM BLEED: Cooling system bleeder valve identification, bleeder type and bleed procedures for most domestic and imported cars and light trucks sold in the U.S. and Canada from 1986+.
PREVENTIVE MAINTENANCE: Preventive maintenance recommendations and required services for most domestic and imported cars and light trucks sold in the U.S. and Canada from 1980+. Includes severe and routine service schedules
QUICK-LUBE and ILLUSTRATIONS: Fluid recommendations, capacities, drain plug torques, tire data, and severe service recommended preventive maintenance schedules. Information covers most 1991 GMC Sonoma cars and light trucks sold in the U.S. and Canada from 1980+. Engine and chassis service images.
- Automatic transmission/transaxles capacities, lubricant recommendations
- Differential/final drive capacities, lube recommendations, grades, & viscosities
- Final drive fill & drain plug torques
- Number of lubrication fittings & plugs
- Power steering, brake, & clutch fluid recommendations
- Manual transmission/transaxle capacities, lube recommendations, grades, & viscosities
- Number of lubrication fittings & plugs
- Power steering, brake, & clutch fluid recommendations
- Engine oil capacities, API grade recommendations, SAE viscosity recommendations, drain plug torque
- Severe service maintenance & interval recommendations
- Tire sizes, wheel nut/bolt torque, pressures & rim sizes
- Transfer case capacities, lube recommendations, grades, & viscosities
TUNE-UP & DRIVEABILITY SPECIFICATIONS: Most tune-up specifications for most 1991 GMC Sonoma cars and light trucks sold in the U.S. and Canada from 1980+
- Airflow sensor electrical specifications
- Tensioning specifications for systems with automatic tensioners
- Barometric pressure sensor specs
- Battery group number and cranking performance
- Crankshaft & camshaft position sensor resistance
- Engine compression pressures
- Coolant temperature sensor specs
- Computer advance.
- Diesel fuel temperature sensor resistance.
- Distributor advance specifications
- Ignition pickup coil resistance
- Exhaust gas recirculation temperature sensor resistance
- Engine fastener torque values
- Firing order diagrams
- Fuel system pressures
- Generator (alternator) specs
- Intake air temperature sensor specs
- Ignition coil specifications
- Fuel injector resistance
- Engine idle speeds
- Knock sensor resistance
- Manifold absolute pressure sensor specs
- Mixture control solenoid resistance
- Voltage regulator specs
- Spark plug applications & gaps
- Starter motor electrical specs.
- Tensioning specifications for systems without automatic tensioners
- Throttle body temperature sensor resistance
- Ignition timing in degrees at rpm
- Transmission oil temperature sensor resistance
- Throttle position sensor specs
- Vacuum sensor valve specs
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