INTRODUCTION
Use this article to quickly find specifications related to servicing and on-vehicle adjustments. This article may be used for quick reference when you are familiar with proper adjustment procedures and only need a specification.
MODEL IDENTIFICATION
Vehicle model is identified by fifth character of Vehicle Identification Number (VIN). VIN is stamped on metal pad on top of left end of instrument panel, near windshield. See MODEL IDENTIFICATION table.
| Series (1) | Model |
|---|
| "C" | 2WD Pickup, Sierra & Suburban |
| "G" | RWD Van |
| "K" | 4WD Blazer, Pickup, Sierra, Suburban & Yukon |
| "L" | AWD Astro & Safari |
| "M" | 2WD Astro & Safari |
| "P" | Commercial Van/Motorhome |
| "S" | 2WD Blazer, Jimmy, Pickup & Sonoma |
| "T" | 4WD Blazer, Bravada, Jimmy, Pickup, Sonoma & Typhoon |
| "U" | Lumina APV, Silhouette & Trans Sport |
| (1) Vehicle series is fifth character of VIN. |
| (1) | Vehicle series is fifth character of VIN. |
CAPACITIES
| Application | Cold Crank Amps @ 0°F (-18°C) | Reserve Minutes |
|---|
| 2.5L (VIN A) |
| Light Duty | 525 | 90 |
| Heavy Duty | 630 | 115 |
| 2.8L (VIN R) | 525 | 90 |
| Light Duty | 525 | 90 |
| Heavy Duty | 630 | 115 |
| 3.1L (VIN D) | 525 | 90 |
| 3.8L (VIN L) | 630 | 90 |
| 4.3L (VIN W & Z) | 630 | 115 |
| Light Duty | 525 | 90 |
| Heavy Duty | 630 | 115 |
| 5.0L (VIN H) | 630 | 115 |
| 5.7L (VIN K) | 630 | 115 |
| 6.2L (VIN C & J) | 570 | 90 |
| 6.5L (VIN F) | 570 | 90 |
| 7.4L (VIN N) | 630 | 115 |
| Application | (1) Quantity: Qts. (L) |
|---|
| Crankcase |
| 2.5L (VIN A) | (2) 4.0 (3.8) |
| 2.8L (VIN R) | (2) 4.5 (4.3) |
| 3.1L (VIN D) | (2) 4.5 (4.3) |
| 3.8L (VIN L) | (2) 4.5 (4.3) |
| 4.3L (VIN W & Z) | (2) (3) 4.5 (4.3) |
| 5.0L (VIN H) | (2) 5.0 (4.8) |
| 5.7L (VIN K) | (2) 5.0 (4.8) |
| 6.2L (VIN C & J) | 7.0 (6.6) |
| 6.5L (VIN F) | 7.0 (6.6) |
| 7.4L (VIN N) | (2) 7.0 (6.6) |
| Cooling System (Includes Heater) (4) |
| 2.5L (VIN A) | 11.5 (11.0) |
| 2.8L (VIN R) | 10.5 (10.0) |
| 3.1L (VIN D) |
| With Rear Heater | 11.0 (10.4) |
| Without Rear Heater | 10.0 (9.5) |
| 3.8L (VIN L) | 11.0 (10.4) |
| With Rear Heater | 11.4 (10.8) |
| Without Rear Heater | 10.0 (9.5) |
| 4.3L (VIN W & Z) |
| "C", "K", "S" & "T" Series | 12.1 (11.5) |
| "G" & "P" Series |
| With Rear Heater | 14.0 (13.2) |
| Without Rear Heater | 11.0 (10.5) |
| "M" & "L" Series |
| With Rear Heater | 16.5 (15.6) |
| Without Rear Heater | 13.5 (12.8) |
| 5.0L (VIN H) | 18.0 (17.0) |
| 5.7L (VIN K) |
| Standard | 18.0 (17.0) |
| Heavy Duty | 27.0 (26.0) |
| 6.2L (VIN C & J) | 25.0 (23.5) |
| 6.5L (VIN F) | 27.0 (26.0) |
| 7.4L (VIN N) |
| Standard | 23.0 (22.0) |
| Heavy Duty | 27.0 (26.0) |
| Automatic Transaxle (Dexron-II) (5) |
| 3.1L (VIN D) | 4.0 (3.8) |
| 3.8L (VIN L) | 6.0 (5.7) |
| Automatic Transmission (Dexron-II) (5) |
| 2.5L (VIN A) | 5.0 (4.7) |
| 2.8L (VIN R) | 5.0 (4.7) |
| 4.3L (VIN W & Z) | 5.0 (4.7) |
| V8 Engines | 5.0 (4.7) |
| Manual Transmission |
| 2.5L (VIN A) | (6) 2.2 (2.0) |
| 2.8L (VIN R) | (6) 2.2 (2.0) |
| 4.3L (VIN W & Z) | (7) 2.2 (2.0) |
| V8 Engines |
| 4-Speed | (8) 4.0 (3.8) |
| 5-Speed | (9) 2.2 (2.0) |
| (1) Fluid capacities listed are approximate. Always fill to FULL mark. (2) Includes oil filter capacity. (3) Use of synthetic 10W-30 motor oil is required on Turbo models. (4) Add 3 qts. (2.8L) coolant for models equipped with rear heater. (5) Drain and refill capacity only. Does not include torque converter. (6) Dexron-II. (7) Manual Transmission Fluid (T2732). (8) GL-4. (9) Manual Transmission Fluid (T2850). |
| (1) | Fluid capacities listed are approximate. Always fill to FULL mark. |
| (2) | Includes oil filter capacity. |
| (3) | Use of synthetic 10W-30 motor oil is required on Turbo models. |
| (4) | Add 3 qts. (2.8L) coolant for models equipped with rear heater. |
| (5) | Drain and refill capacity only. Does not include torque converter. |
| (7) | Manual Transmission Fluid (T2732). |
| (9) | Manual Transmission Fluid (T2850). |
SERVICE INTERVALS & SPECIFICATIONS
| Component | Interval (Miles) |
|---|
| Air Filter | 30,000 |
| Coolant | 30,000 |
| Fuel Filter | (1) 60,000 |
| Oil & Filter | (2) (3) 7500 |
| Spark Plugs | 30,000 |
| (1) On diesel engines, replace every 30,000 miles. (2) On diesel engines, replace every 5000 miles. (3) On turbo models, replace every 3000 miles. |
| (1) | On diesel engines, replace every 30,000 miles. |
| (2) | On diesel engines, replace every 5000 miles. |
| (3) | On turbo models, replace every 3000 miles. |
BELT TENSION
| Application | Tension: Lbs. (kg) |
|---|
| All Models | (1) |
| (1) Serpentine belt tension is maintained automatically by a spring-tensioned idler pulley. No adjustment is necessary. |
| (1) | Serpentine belt tension is maintained automatically by a spring-tensioned idler pulley. No adjustment is necessary. |
ENGINE COMPRESSION
| Application | Compression Ratio |
|---|
| 2.5L (VIN A) | 8.3:1 |
| 2.8L (VIN R) | 8.9:1 |
| 3.1L (VIN D) | 8.5:1 |
| 3.8L (VIN L) | 8.5:1 |
| 4.3L |
| VIN W & Z (Except Turbo) | 9.1:1 |
| VIN Z (Turbo) | 8.35:1 |
| 5.0L (VIN H) | 9.1:1 |
| 5.7L (VIN K) | (1) 9.1:1 |
| 6.2L Diesel (VIN C & J) | 21.3:1 |
| 6.5L Turbo Diesel (VIN F) | 21.0:1 |
| 7.4L (VIN N) | 7.9:1 |
| (1) Compression ratio is 8.3:1 for vehicles with GVW greater than 8500 lbs. |
| (1) | Compression ratio is 8.3:1 for vehicles with GVW greater than 8500 lbs. |
COMPRESSION SPECIFICATIONS
VALVE CLEARANCE
Note. All models are equipped with hydraulic lifters. No adjustments are required.
IGNITION COIL
| Application | Ohms |
|---|
| All Models | 500-1500 |
HIGH TENSION WIRE RESISTANCE
| Application | Ohms |
|---|
| All Models | 30,000 Maximum |
HIGH TENSION WIRE RESISTANCE
SPARK PLUGS
| Application | AC |
|---|
| 2.5L (VIN A) | R43CTS6 |
| 2.8L (VIN R) | R43TSK |
| 3.1L (VIN D) | R43TS |
| 3.8L (VIN L) | 41-600 |
| 4.3L |
| VIN W & Z (Except Turbo) | CR43TS |
| VIN Z (Turbo) | CR42TS |
| 5.0L (VIN H), 5.7L (VIN K) & 7.4L (VIN N) | CR43TS |
| Application | Gap: In. (mm) | Torque: Ft. Lbs. (N.m) |
|---|
| 2.5L (VIN A) | .060 (1.52) | 11 (15) |
| 2.8L (VIN R) | .045 (1.14) | 11 (15) |
| 3.1L (VIN D) | .045 (1.14) | 20 (27) |
| 3.8L (VIN L) | .060 (1.52) | 20 (27) |
| 4.3L |
| VIN W & Z (Except Turbo) | .045 (1.14) | 11 (15) |
| VIN Z (Turbo) | .045 (1.14) | 11 (15) |
| 5.0L (VIN H) | .035 (0.89) | 11 (15) |
| 5.7L (VIN K) | .035 (0.89) | 11 (15) |
| 7.4L (VIN N) | .035 (0.89) | 11 (15) |
SPARK PLUG SPECIFICATIONS
FIRING ORDER & TIMING MARKS
Firing Order & Timing Marks (2.5L). Scheme 1
Scheme 1: Firing Order & Timing Marks (2.5L)
Firing Order & Timing Marks (2.8L). Scheme 2
Scheme 2: Firing Order & Timing Marks (2.8L)
Firing Order & Timing Marks (3.1L). Scheme 3
Scheme 3: Firing Order & Timing Marks (3.1L)
Firing Order & Timing Marks (3.8L). Scheme 4
Scheme 4: Firing Order & Timing Marks (3.8L)
Firing Order & Timing Marks (4.3L). Scheme 5
Scheme 5: Firing Order & Timing Marks (4.3L)
Firing Order & Timing Marks (5.0L, 5.7L & 7.4L). Scheme 6
Scheme 6: Firing Order & Timing Marks (5.0L, 5.7L & 7.4L)
Firing Order (6.2L & 6.5L Diesel). Scheme 7
Scheme 7: Firing Order (6.2L & 6.5L Diesel)
IGNITION TIMING
Note. For timing adjustment procedures, see ADJUSTMENTS article in this section.
| Application | (1) Man. Trans. | (2) Auto. Trans. |
|---|
| 2.5L (VIN A) | 8 @ Idle | 8 @ Idle |
| 2.8L (VIN R) | 10 @ Idle | 10 @ Idle |
| 3.1L (VIN D) | 10 @ Idle | 10 @ Idle |
| 3.8L (VIN L) | (3) | (3) |
| 4.3L (VIN W & Z) | 0 @ Idle | 0 @ Idle |
| 5.0L (VIN H) | 0 @ Idle | 0 @ Idle |
| 5.7L (VIN K) | 0 @ Idle | 0 @ Idle |
| 7.4L (VIN N) | 4 @ Idle | 4 @ Idle |
| (1) With transmission in Neutral. (2) With transmission in Neutral or Park. (3) Timing is not adjustable. |
| (1) | With transmission in Neutral. |
| (2) | With transmission in Neutral or Park. |
| (3) | Timing is not adjustable. |
IGNITION TIMING (Degrees BTDC @ RPM)
FUEL PUMP
| Application | Psi (kg/cm 2 ) |
|---|
| 3.8 L (VIN L) | 41-47 (2.9-3.3) |
| 4.3L (VIN W) | 55-61 (3.9-4.3) |
| 4.3L (VIN Z Turbo) (1) | 38-43 (2.7-3.3) |
| 6.2L Diesel (VIN C & J) | 5.8-8.7 (.41-.61) |
| 6.5L Turbo Diesel (VIN F) | (2) |
| All Others | 9-13 (.63-.91) |
| (1) 4.3L (VIN Z) turbo is used in Typhoon version of Jimmy. (2) Information is not available from manufacturer. |
| (1) | 4.3L (VIN Z) turbo is used in Typhoon version of Jimmy. |
| (2) | Information is not available from manufacturer. |
INJECTOR RESISTANCE
| Application | Ohms |
|---|
| 3.1L (VIN D) | 1.2 |
| 4.3L (VIN Z Turbo) (1) | 2.0 |
| All Others | 1.3 |
| (1) 4.3L (VIN Z) turbo is used in Typhoon version of Jimmy. (2) Injector resistance specification is at 140°F (60°C). |
| (1) | 4.3L (VIN Z) turbo is used in Typhoon version of Jimmy. |
| (2) | Injector resistance specification is at 140°F (60°C). |
INJECTOR RESISTANCE SPECIFICATIONS (2)
IDLE SPEED & MIXTURE
Note. Idle mixture on fuel injected models is controlled by the Electronic Control Module (ECM) and is not adjustable. Controlled idle speed and IAC count can be checked using scan tester. See CONTROLLED IDLE SPEED & IAC COUNT table.
| Application | Idle RPM | (1) IAC Counts |
|---|
| 2.5L TBI |
| "S" Series |
| Auto. Trans. (2) | 800 | 15-40 |
| Man. Trans. (3) | 900 | 5-20 |
| 2.8L TBI |
| "S" Series |
| Auto. Trans. (2) | 800 | 5-20 |
| 3.1L TBI |
| "U" Series |
| Auto. Trans. (2) | 600-700 | 5-15 |
| 3.8L PFI |
| "U" Series |
| Auto. Trans. (2) | 650-750 | 16-20 |
| 4.3L CPI |
| "L" Series |
| Auto. Trans. (2) | 625 | 15-50 |
| "M", "S" & "T" Series |
| Auto. Trans. (2) | 550 | 5-40 |
| 4.3L PFI Turbo |
| "S" & "T" Series |
| Auto. Trans. (2) | (4) | 1-50 |
| 4.3L TBI |
| "C" & "K" Series |
| Auto. Trans. (2) (5) | 537 | 5-30 |
| Auto. Trans. (2) (5) | 650 | 20-35 |
| Man. Trans. (3) | 550 | 2-20 |
| "G" Series |
| Auto. Trans. (2) | 538 | 5-30 |
| Man. Trans. (3) | 650 | 5-30 |
| "L" Series |
| Auto. Trans. (2) | 625 | 5-50 |
| Man. Trans. (3) | 600 | 3-30 |
| "M" Series |
| Auto. Trans. (2) | 538 | 5-30 |
| "P" Series |
| Auto. Trans. (2) | 650 | 20-35 |
| 5.0L TBI |
| "C" & "K" Series |
| Auto. Trans. (2) | 500 | 5-30 |
| Man. Trans. (3) | 600 | 5-30 |
| 5.7L TBI |
| "C", "G", "K" & "P" Series |
| Under 8500 GVW |
| Auto. Trans. (2) | 550 | 5-30 |
| Man. Trans. (3) | 660 | 5-30 |
| Over 8500 GVW |
| Auto. Trans. (2) | 550 | 5-30 |
| Man. Trans. (3) | 600 | 5-30 |
| 7.4L TBI |
| "C", "G", "K" & "P" Series |
| Auto. Trans. (2) | 750 | 5-30 |
| Man. Trans. (3) | 800 | 5-30 |
| (1) Add 2 counts for engines with less than 500 miles. On 4.3L and V8 engines, add 2 counts for every 1000 ft. above sea level. On 2.5L and 2.8L engines, add one count for every 1000 ft. above sea level. (2) Automatic transmission in Drive. (3) Manual transmission in Neutral. Tech 1 scan tester will display "RDL" with transmission in Neutral. (4) Set to +/-50 RPM from desired idle speed in Drive. (5) Calibration identification is not given by manufacturer. IAC count and actual RPM should correspond to one of these calibrations. |
| (1) | Add 2 counts for engines with less than 500 miles. On 4.3L and V8 engines, add 2 counts for every 1000 ft. above sea level. On 2.5L and 2.8L engines, add one count for every 1000 ft. above sea level. |
| (2) | Automatic transmission in Drive. |
| (3) | Manual transmission in Neutral. Tech 1 scan tester will display "RDL" with transmission in Neutral. |
| (4) | Set to +/-50 RPM from desired idle speed in Drive. |
| (5) | Calibration identification is not given by manufacturer. IAC count and actual RPM should correspond to one of these calibrations. |
CONTROLLED IDLE SPEED & IAC COUNT
MINIMUM IDLE SPEED
Note. Minimum idle speed adjustment can only be performed on the 7.4L engines. For minimum idle speed adjustment procedures, see ADJUSTMENTS article in this section.
| Application | RPM |
|---|
| 7.4L |
| Auto. Trans. (2) | 600-650 |
| Man. Trans. (3) | 675-725 |
| (1) Idle speed with seated IAC is lower than specified if engine has less than 500 miles or when checked at altitudes above 1500 feet. (2) Automatic transmission in Drive. (3) Manual transmission in Neutral. |
| (1) | Idle speed with seated IAC is lower than specified if engine has less than 500 miles or when checked at altitudes above 1500 feet. |
| (2) | Automatic transmission in Drive. |
| (3) | Manual transmission in Neutral. |
THROTTLE POSITION (TP) SENSOR
Note. TP sensor is adjustable only on 6.2L diesel engines. For further testing, see appropriate TESTS W/CODES article in this section. For adjustment procedure, see ADJUSTMENTS article in this section.
