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Maintenance Information - S & T Series GMC Cab & Chassis R2500

Procedures 9 illustrations ~1919 words

VIN LOCATION

The Vehicle Identification Number (VIN) is located on the left side of the dash panel at the base of the windshield. The VIN chart explains the code characters.

SERVICE PARTS IDENTIFICATION LABEL

Label is located inside glove box door and has the vehicle's VIN, wheelbase, paint information, and a list of all production options and special equipment.

VIN CODE ID EXPLANATION

Numbers preceding the explanations in the legend below refer to the sequence of characters as listed on VIN identification label. See VIN example below.

VIN Code ID Explanation. Scheme 31

Scheme 31: VIN Code ID Explanation
Scheme 31: VIN Code ID Explanation

SEVERE & NORMAL SERVICE DEFINITIONS

Note. Use the Severe Service schedule if the vehicle to be serviced is operated under ANY (one or more) of these conditions

Service is recommended at mileage intervals based on vehicle operation and time in service. Manufacturer's Schedules identify items to be serviced based on type of operation. Service schedules are based on the following primary operating conditions

Severe Service

  1. Short Trips (4 Miles Or Less)
  2. Freezing Temperatures
  3. Towing Or Heavily Loaded
  4. Severe Dust Conditions
  5. Hot Weather, Stop-And-Go Driving
  6. Extensive Idling Conditions (Taxi Or Delivery Type Service)

Normal Service

  1. No Severe Service Operating Conditions

CAMSHAFT TIMING BELT (2.2L DIESEL)

CAUTIONFailure to replace a faulty camshaft timing belt may result in serious engine damage.

The condition of camshaft drive belts should always be checked on vehicles which have more than 50,000 miles. Although some manufacturers do not recommend belt replacement at a specified mileage, others require it at 60,000-100,000 miles. A camshaft drive belt failure may cause extensive damage to internal engine components on most engines, although some designs do not allow piston-to-valve contact. These designs are often called "Free Wheeling".

Many manufacturers changed their maintenance and warranty schedules in the mid-1980's to reflect timing belt inspection and/or replacement at 50,000-60,000 miles. Most service interval schedules in this manual reflect these changes.

Belts or components should be inspected and replaced if any of the following conditions exist

  1. Cracks Or Tears In Belt Surface
  2. Missing, Damaged, Cracked Or Rounded Teeth
  3. Oil Contamination
  4. Damaged Or Faulty Tensioners
  5. Incorrect Tension Adjustment

Scheme 32

Scheme 32: SERVICE POINT LOCATIONS
Scheme 32: SERVICE POINT LOCATIONS

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Scheme 37

Note. For more information regarding jacking or hoisting the vehicle, refer to the JACKING & HOISTING article in the WHEEL ALIGNMENT section.

SERVICE LABOR TIMES

Note. For 1990 and newer vehicles, labor times are provided, where available, within appropriate SERVICE INTERVAL table in SCHEDULED SERVICES article.

WHEEL & TIRE SPECIFICATIONS

Wheel and tire information can be found on the Certification/Tire label attached to rear of driver's door or door pillar.

Note. DO NOT use chains with P235/75R15 size tires. Vehicle damage may result.

WHEEL SIZE

Replacement wheels should match originals in load limit, diameter, width, offset, and mounting configuration. The wrong wheel can cause difficulty with bearing life, brake cooling, speedometer/odometer calibration, stopping ability, headlight aim, bumper height, vehicle ground clearance and tire or tire chain clearance to body and chassis.

WHEEL TIGHTENING

Tighten lug nuts on steel wheels to 80 ft. lbs. (108 N.m). Tighten lug nuts on aluminum wheels to 90 ft. lbs. (122 N.m). 1993 models should be tightened to 95-100 ft. lbs. (130-140 N.m).

BATTERY SPECIFICATIONS

CAUTIONWhen battery is disconnected, vehicles equipped with computers may lose memory data. When battery power is restored, driveability problems may exist on some vehicles. These vehicles may require a relearn procedure. See COMPUTER RELEARN PROCEDURES article in the GENERAL INFORMATION section.

ANTI-LOCK BRAKE SYSTEM

The anti-lock brake system contains electronic equipment that can be susceptible to interference caused by improperly installed or high output radio transmitting equipment. Since this interference could cause the possible loss of the anti-lock braking capability, such equipment should be installed by qualified professionals.

On models equipped with anti-lock brake systems, ALWAYS observe the following cautions

  1. DO NOT attempt to bleed hydraulic system without first referring to the appropriate ANTI-LOCK BRAKE SYSTEM article in the BRAKES Section.
  2. DO NOT mix tire sizes. As long as tires remain close to the original diameter, increasing the width is acceptable. Rolling diameter must be identical for all 4 tires. Some manufacturers recommend tires of the same brand, style and type. Failure to follow this precaution may cause inaccurate wheel speed readings.
  3. Use ONLY recommended brake fluids. DO NOT use silicone brake fluids in an ABS-equipped vehicle.

REPLACING BLOWN FUSES

CAUTIONBefore replacing a blown fuse, remove ignition key, turn off all lights and accessories to avoid damaging the electrical system. Be sure to use fuse with the correct indicated amperage rating. The use of an incorrect amperage rating fuse may result in a dangerous electrical system overload.

BATTERY WARNING

WARNINGWhen battery is disconnected, vehicles equipped with computers may lose memory data. When battery power is restored, driveability problems may exist on some vehicles. These vehicles may require a relearn procedure. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION section.

BRAKE PAD WEAR INDICATOR

Indicator will cause a squealing or scraping noise, warning that brake pads need replacement.

CATALYTIC CONVERTER (GASOLINE MODELS)

CAUTIONTo prevent catalytic converter overheating, DO NOT allow engine to idle for more than 20 minutes.

COOLANT (PROPYLENE-GLYCOL FORMULATIONS)

CAUTIONTo avoid possible damage to vehicle use only ethylene-glycol based coolants with a mixture ratio from 44-68% anti-freeze. DO NOT use 100% anti-freeze as it will cause the formation of cooling system deposits. This results in coolant temperatures of over 300° F (149°C) which can melt plastics. 100% anti-freeze has a freeze point of only -8° F (-22°C).
CAUTIONPropylene-Glycol Mixtures has a smaller temperature range than Ethylene-Glycol. The temperature range (freeze-boil) of a 50/50 Anti-Freeze/Water Mix is as follows: Propylene-Glycol -26° F (-32°C) - 257° F (125°C) Ethylene-Glycol -35° F (-37°C) - 263° F (128°C)
CAUTIONPropylene-Glycol/Ethylene-Glycol Mixtures can cause the destabilization of various corrosion inhibitors. Also Propylene-Glycol/Ethylene-Glycol has a different specific gravity than Ethylene-Glycol coolant, which will result in inaccurate freeze point calculations.

DIESEL FUEL ANTI-FUNGAL ADDITIVES

CAUTIONIf fuel contamination due to fungi or other microorganisms is suspected a fuel additive with a biocide may be used. Follow the manufacturers dosage as recommended on product label. Use biocides ONLY when necessary, excessive use can may cause other fuel system problems.

DIESEL FUEL CONTAMINATION

WARNINGDiesel fuel system may be contaminated with fungi or other microorganisms. Keep contaminated fuel away from open skin cuts or sores to prevent skin irritation or infection.

DIESEL FUEL REQUIREMENTS

CAUTIONAll diesel engines are to use Diesel Fuel #2 when the outside temperature is above 20°F (-7°C). In temperatures that are below 20°F (-7°C) use Diesel Fuel #1, this will reduce the chance of the fuel thickening and forming wax.

Note. A Diesel Fuel #1 & #2 combination (Blended Fuel) may be used, and is recommended for mild winter driving.

ELECTROSTATIC DISCHARGE SENSITIVE (ESD) PARTS

WARNINGMany solid state electrical components can be damaged by static electricity (ESD). Some will display a warning label, but many will not. Discharge personal static electricity by touching a metal ground point on the vehicle prior to servicing any ESD sensitive component.

FUEL SYSTEM SERVICE

WARNINGRelieve fuel system pressure prior to servicing any fuel system component.

HALOGEN BULBS

WARNINGHalogen bulbs contain pressurized gas which may explode if overheated. DO NOT touch glass portion of bulb with bare hands. Eye protection should be worn when handling or working around halogen bulbs.

METHANOL GASOLINE

CAUTIONFuel that is more than 5% methanol should not be used in this vehicle. It can corrode metal parts in the fuel system, and damage plastic and rubber parts. Even at 5% methanol or less, solvents and corrosion preventers must be used with this fuel to avoid these problems.

RADIATOR CAP

CAUTIONAlways disconnect the fan motor when working near the radiator fan. The fan is temperature controlled and could start at any time even when the ignition key is in the OFF position. DO NOT loosen or remove radiator cap when cooling system is hot.

RADIATOR FAN

WARNINGKeep hands away from radiator fan.

SPARK PLUGS

Note. Allow engine to cool before removing spark plugs from aluminum cylinder heads.

WARRANTY INFORMATION

CAUTIONDue to the different warranties offered in various regions and the variety of after-market extended warranties available, please refer to the warranty package that came with the vehicle to verify all warranty options.

BUMPER-TO-BUMPER PLUS COVERAGE LIMITED WARRANTY

Entire vehicle (except battery) is covered for 3 years or 50,000 miles, whichever occurs first. Covered by this warranty are any repairs to vehicle components which have proven defective in material and workmanship under normal use (tires excluded). Warranty repairs (parts and labor) will be made by the Dealer at no charge using new or remanufactured parts. This warranty is subject to a 100 deductible for each repair visit after the first year or 12,000 miles, whichever occurs first.

BATTERY COVERAGE

Covers replacement cost of battery for 3 years or 50,000 miles (36,000 miles on 1992 models), whichever occurs first. A prorated charge applies after first 12 months or 12,000 miles, whichever occurs first.

CORROSION COVERAGE

Covers any body sheet metal panel that is perforated due to corrosion. Coverage is for 6 years or 100,000 miles, whichever occurs first.

EMISSIONS "DEFECT" & "PERFORMANCE" WARRANTIES (FEDERAL)

Defect Warranty ensures vehicle meets applicable EPA regulations and that emission control system is free from defects in materials and workmanship. Coverage is for a period of 5 years or 50,000 miles, whichever occurs first.

Performance Warranty covers all costs of repairing or adjusting any components or parts as needed in order for the vehicle to pass a federally-required state or local emissions test. Other emission control parts related to these components are covered by the Performance Warranty, where applicable. If another part fails due to the failure of one of these components, both parts are covered. See customer's copy of warranty information for specific items covered.

EMISSION "PERFORMANCE" WARRANTY (CALIFORNIA)

If vehicle fails a Smog Check inspection, all necessary repairs and adjustments will be made by manufacturer to ensure vehicle passes inspection. Coverage is for 3 years or 50,000 miles, whichever occurs first.

EMISSION "DEFECT" WARRANTY (CALIFORNIA)

If any emission-related part on the vehicle is defective, the part will be repaired or replaced by manufacturer. Coverage is for 3 years or 50,000 miles, whichever occurs first.

Some emission-related parts are covered for 7 years or 70,000 miles, whichever occurs first, and will be repaired or replaced by manufacturer if found to be defective in material or workmanship. See customer's copy of warranty information for specific items covered.

FUSE PANEL LOCATIONS

The fuse block is located under the instrument panel to the left of the steering column.

Scheme 38

Scheme 38: FUSE PANEL IDENTIFICATION (1983-84)
Scheme 38: FUSE PANEL IDENTIFICATION (1983-84)

Fuse & Circuit Breaker Identification (1983-84)

  1. 1 - Choke 20 Amp - Electric Choke
  2. 2 - Htr-A/C 20 Amp - Heater & A/C, Generator Gauge
  3. 3 - Aux-Htr-A/C 25 Amp - Auxiliary Heater & Rear A/C
  4. 4 - Gau/Idle 20 Amp - Warning Gauges, Idle Stop Solenoid, Warning Lights
  5. 5 - Radio 15 Amp - Radio, Automatic Transmission (MD8), Auxiliary Battery
  6. 6 - Stop-Haz 15 Amp - Hazard Flasher, Stoplights
  7. 7 - Ign 20 Amp - Tachometer, Diesel Warning Lights, Cruise Control, Auxiliary Fuel Tank, 4-Wheel Drive Indicator Light, Auto. Trans. (M40)
  8. 8 - T/L-Ctsy 20 Amp - Courtesy Lights, Taillights & Parking Lights
  9. 9 - Wiper 25 Amp - Windshield Washer/Wiper
  10. 10 - Turn-B/U 15 Amp - Back-Up Light Switch, Turn Signal Flasher
  11. 11 - Horn-Dim 20 Amp - Horn, Cargo & Dome Lights, Headlight Warning, Lighter, Clock
  12. 12 - Inst-Lps 5 Amp - Instrument Panel Lights, Light Switch Rheostat, Headlight Warning
  13. 13 - Wdo 30 Amp (Circuit Breaker) - Power Windows
  14. 14 - Pwr-Accy 30 Amp (Circuit Breaker) - Power Door Locks

In-line Fuse Identification (1983-84)

  1. HOOD 5 Amp - Underhood Lamp
  2. Trailer 30 Amp - Trailer Wiring Harness (If Equipped with Tow Package)

Scheme 39

Scheme 39: FUSE PANEL ID (1985-88)
Scheme 39: FUSE PANEL ID (1985-88)

Fuse & Circuit Breaker ID (1985-88)

  1. 1 - Inst-Lps 5 Amp - Instrument Panel Lights, Headlight Warning Buzzer, Ashtray Light, 4WD Indicator Light, Foglight Switch Light
  2. 2 - Pwr-Accy 30 Amp (Circuit Breaker) - Power Door Locks, Console Accessory Receptacles, CD Player (If Equipped), Power Seat (If Equipped), Elec. Shift Transfer Case (If Equipped)
  3. 3 - Horn-Dim 20 Amp - Horn, Clock & Lighter, Dome & Glove Box Lights, Courtesy & Vanity Mirror Lights, Power Mirrors
  4. 4 - Ign-Gau 20 Amp - Ignition (1985-87), Indicator Lights & Gauges, A/T Converter Clutch & Cruise Control, RWAL Brake Signal (If Equipped), Seat Belt Timer, A/C Compressor Timer (If Equipped), 4WD Indicator Light (If Equipped)
  5. 5 - Choke 20 Amp (1985) - Not Used (1986-88) Choke (1985)
  6. 6 - Stop-Haz 15 Amp - Stoplights & Hazard Warning Lights
  7. 7 - T/L-Ctsy 20 Amp - Light Switch, Taillights & Parking Lights, Courtesy Lights, Electronic Cluster (If Equipped)
  8. 8 - Turn-B/U 15 Amp - Turn Signal & Back-Up Lights
  9. 9 - Htr-A/C 25 Amp - Heating & A/C
  10. 10 - Radio 15 Amp - Radio, Tachometer, Rearview Mirror Map Lights
  11. 11 - ECM B 10 Amp - Electronic Control Module, Fuel Pump
  12. 12 - ECM I 10 Amp - Electronic Control Module
  13. 13 - Pwr Wdo 30 Amp (Circuit Breaker) - Power Windows
  14. 14 - Wiper 25 Amp - Windshield Wipers & Washers
  15. 15 - Crank 3 Amp - Electronic Control Module
  16. 16 - Not Used
  17. 17 - Not Used

In-line Fuse Identification (1985-88)

  1. Trailer 30 Amp - Trailer Wiring Harness (If Equipped with Tow Package)

Fuse & Circuit Breaker ID (1989-90)

  1. 1 - Inst-Lps 5 Amp - Instrument Panel Lights, Headlight Warning Buzzer, Ashtray Light, 4WD Indicator Light, Foglight Switch Light
  2. 2 - Pwr-Accy 30 Amp (Circuit Breaker) - Power Door Locks, Console Accessory Receptacles, CD Player (If Equipped), Power Seat (If Equipped), Elec. Shift Transfer Case (If Equipped)
  3. 3 - Horn-Dim 20 Amp - Horn, Clock & Lighter, Dome & Glove Box Lights, Courtesy & Vanity Mirror Lights, Fog Lights (1991-93), Power Mirrors
  4. 4 - Ign-Gau 20 Amp - Ignition (1985-87), Indicator Lights & Gauges, A/T Converter Clutch & Cruise Control, RWAL Brake Signal (If Equipped), Seat Belt Timer, A/C Compressor Timer (If Equipped), 4WD Indicator Light (If Equipped)
  5. 5 - Brake 15 Amp - Rear/Four Wheel Anti-Lock Brake Module, Speedometer, Digital Radio Adapter Module, Auto. Trans. Converter Clutch
  6. 6 - Stop-Haz 15 Amp - Stoplights & Hazard Warning Lights, Chime Module (1991-93)
  7. 7 - T/L-Ctsy 20 Amp - Light Switch, Taillights & Parking Lights, Courtesy Lights, Electronic Cluster (If Equipped)
  8. 8 - Turn-B/U 15 Amp - Turn Signal & Back-Up Lights
  9. 9 - Htr-A/C 25 Amp - Heating & A/C
  10. 10 - Radio 15 Amp - Radio, Tachometer, Rearview Mirror Map Lights, Compass (1993)
  11. 11 - ECM B 10 Amp - Electronic Control Module, Fuel Pump
  12. 12 - ECM I 10 Amp - Electronic Control Module
  13. 13 - Pwr Wdo 30 Amp (Circuit Breaker) - Power Windows
  14. 14 - Wiper 25 Amp - Windshield Wipers & Washers
  15. 15 - Crank 3 Amp - Electronic Control Module
  16. 16 - TCCM 5 Amp (1993) - Elec. Shift Transfer Case Module
  17. 17 - DRL 10 Amp (1991-93) - Daytime Running Lights (Canada)

In-line Fuse Identification (1989-90)

  1. Trailer 30 Amp - Trailer Wiring Harness (If Equipped with Tow Package)
  2. CD Player (1992) 10 Amp - CD Player (If Equipped)
  3. AUX PWR OUTLET 10 Amp - Auxiliary Power (If Equipped)

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