CHEVROLET TRUCKS --------—■*“ .— FOREWORD This manual includes procedures involved in disassembly and assembly of components listed in the "Table of Contents.” This manual should be kept in a handy place for ready reference. If properly used, it will . meet the needs of technicians and vehicle owners. CAUTION: These vehicles contain some parts dimensioned in the metric system as well as in the customary system. Some fasteners are metric and are very close in dimension to familiar customary fasteners in the inch system. It is important to note that, during any vehicle maintenance procedures, replacement fasteners must have the same measurements and strength as those removed, whether metric or customary. (Numbers on the heads of metric bolts and on surfaces of metric nuts indicate their strength. Customary bolts use radial lines for this purpose, while most customary nuts do not have strength markings.) Mismatched or incorrect fasteners can result in vehicle damage or malfunction, or possibly personal injury. Therefore, fasteners removed from the vehicle should be saved for re-use in the same loca­ tion whenever possible. Where the fasteners are not satisfactory for re-use, care should be taken to select a replacement that matches the original. For information and assistance, see your authorized dealer. CHEVROLET MOTOR DIVISION .General Motors Corporation Warren, Michigan No part of this publication may be reproduced, stored in any retrieval system or transmit­ ted, in any form or by any means, including but not limited to electronic, mechanical, photo­ copying, recording or otherwide, without the prior written permission of the Chevrolet Motor Division of General Motors Corp. This includes all text, illustrations, tables and charts. CAUTION To reduce the chance of personal injury and/or property damage, the fol­ lowing instructions must be carefully observed. Proper service and repair are important to the safety of the service techni­ cian and the safe, reliable operation of all motor vehicles. If part replacement is necessary, the part must be replaced with one of the same part number or with an equivalent part. Do not use a replacement part of lesser quality. The service procedures recommended and described in this service man­ ual are effective methods of performing service and repair. Some of these procedures require the use of tools specially designed for the purpose. Accordingly, anyone who intends to use a replacement part, service pro­ cedure or tool, which is not recommended by the vehicle manufacturer, must first determine that neither his safety nor the safe operation of the vehicle will be jeopardized by the replacement part, service procedure or tool selected. It is important to note that this manual contains various Cautions and No­ tices that must be carefully observed in order to reduce the risk of personal injury during service or repair, or the possibility that improper service or repair may damage the vehicle or render it unsafe. It is also important to understand that these ‘Cautions’ and ‘Notices’ are not exhaustive, because it is impossible to warn of all the possible hazardous consequences that might result from failure to follow these instructions. 1991 LIGHT TRUCK UNIT REPAIR MANUAL When reference is made in this manual to a brand name, number, or specific tool, an equivalent product may be used in place of the recommended item. All information, illustrations, and specifications contained in this manual are based on the latest product information available at the time of publication approval. The right is reserved to make changes at any time without notice. ST 333-91 ©1990 General Motors Corporation June, 1990 Printed in U.S.A. All rights reserved TABLE OF CONTENTS The Table of Contents on this page indicates the sections covered in this manual. At the beginning of each individual section is a Table of Contents which gives the page number on which each major subject begins. SECTION SUBJECT CONTENTS GENERAL OA GENERAL INFORMATION n U INFORMATION 1B1 A6 AIR CONDITIONING 1B4 HR-6HE AIR CONDITIONING COMPRESSOR COMPRESSOR A AIR 1B2 V5 AIR CONDITIONING 1B5 SD-709 AIR CONDITIONING 1 CONDITIONING COMPRESSOR COMPRESSOR 1B3 R-4 AIR CONDITIONING COMPRESSOR 3 STEERING 3B2 MANUAL STEERING GEAR 3B3 POWER STEERING 4B REAR AXLE 4C FRONT AXLE 4B1 7 1/2 and 7 5/8-INCH RING GEAR 4C1 8 1/2-INCH RING GEAR 4B2 8 1 /2-INCH RING GEAR 4C2 9 3/4-INCH RING GEAR 4B3 9 1 /2-INCH RING GEAR 4C3 7 1/4-INCH RING GEAR 4 AXLE 4B4 10 1/2-INCH RING GEAR 4C4 8 1/4 AND 9 1/4-INCH RING 4B5 DANA REAR AXLES GEAR 4B6 12 INCH RING GEAR 4C5 ALL WHEEL DRIVE—7 1/4-INCH (ROCKWELL) RING GEAR 4B7 LOCKING DIFFERENTIALS 5 BRAKES 5 BRAKES 6 ENGINE 6C THROTTLE BODY INJECTION 6A GENERAL ENGINE UNITS - 6A1 2.5L L4 ENGINE 6C1 TBI UNIT MODEL 220 6A2 2.8L V6 ENGINE 6C2 TBI UNIT MODEL 700 6 ENGINE 6A3 4.3L V6 ENGINE 6D ENGINE ELECTRICAL 6A5 V8 ENGINES 6D1 SI SERIES GENERATORS 6A7 6.2L DIESEL ENGINE 6D2 CS-144 GENERATOR 6D3 SD STARTING MOTORS 6D4 DISTRIBUTORS 7A AUTOMATIC TRANSMISSION 7D TRANSFER CASE 7A1 4L60 AUTOMATIC 7D1 NEW PROCESS 205 TRANSFER TRANSMISSION CASE (7A2) 4L80E AUTOMATIC 7D2 NEW PROCESS 241 TRANSFER 7 TRANSMISSIONS TRANSMISSION CASE 7B1 5LM60 MANUAL TRANSMISSION 7D3 NEW PROCESS 231 TRANSFER { 7B2 117 MANUAL TRANSMISSION CASE 7B3 BORG-WARNER T5 MANUAL TRANSMISSION GENERAL INFORMATION OA-1 SECTION OA GENERAL INFORMATION CONTENTS SUBJECT PAGE Service Parts Identification Label 0A- 1 Vehicle Identification Number OA- 1 Certification Label 0A- 1 Engine Identification Number 0A- 2 llansmission Identification Number 0A- 3 Model Reference 0A- 3 Metric Fasteners 0A- 3 Fastener Strength Identification 0A» 4 Six Lobed Socket Head Fasteners OA- 5 Prevailing Torque Fasteners 0A- 5 Conversion Table OA-15 Decimal and Metric Equivalents OA-16 SERVICE PARTS support. To find out the manufacturer, model and chas­ sis type, engine type, GVW range, model year, plant IDENTIFICATION LABEL code, and sequential number, refer to figure 3. CERTIFICATION LABEL The truck service parts identification label is provided on all models (figure 1). It is located on the inside of The certification label shows the GVWR, the front the instrument panel compartment (or on an inner body and rear GAWRs, and the payload rating for the vehicle panel for Forward Control models). The label lists the (figure 4). VIN (Vehicle Identification Number), wheelbase, paint Gross Vehicle Weight (GVW) is the weight of the information and all production options or special equip­ orginally equipped vehicle and all items added to it ment on the vehicle when it was shipped from the after it has left the factory. This would include bodies, factory. ALWAYS REFER TO THIS INFORMATION winches, booms, etc.; the driver and all occupants, and WHEN ORDERING PARTS. the load the vehicle is carrying. The GVW must not exceed the GVWR. Also, the front and rear gross axle VEHICLE IDENTIFICATION weights must not exceed the front and rear GAWRs. NUMBER The payload rating shown on the label is the maxi­ mum allowable cargo load (including the weight of the The VIN is the legal identifier of the vehicle. On all driver and all occupants) that the vehicle can carry models except the Forward Control, it is located on a plate which is attached to the left top of the instrument panel and can be seen through the windshield from the outside of the vehicle (figure 2). On Forward Control models, the plate is mounted to the top of the radiator 2 1. VIN 6 5 2. Wheel Base 5. RPO/SEO Codes 1. Typical VIN 3. Model Number 6. Exterior Color WA Numbers 4. Order Number 7. Paint System pcArr F7557 Figure 1—Service Parts Identification Label Figure 2—VIN Location OA-2 GENERAL INFORMATION VEHICLE INDENTIFICATION NUMBER (VIN) ~ T H , Nation of Origin 1 - U S Built Code Series 2 - Canadian Built 1 'k Ton 3 * Mexican Built 2 ^ Ton 3 1 Ton Assembly Plant Manufacturers B Baltimore, MD G « General Motors Code Body Type Code Year E Pontiac East, Ml 0 Chassis Only M 1991 JF JFalinnet, sMvill le, Wl Code Make 1 Hi-Cube/Cutaway Van S St. Louis, MO A Chevrolet Bus* 2 Forward Control V Pontiac, Ml B Chevrolet Incomplete 3 Four-Door Cab/Utility Z Fort Wayne, IN C Chevrolet Truck 4 Two-Door Cab 0 Pontiac, Ml D GMC Incomplete 5 Van 1 Oshawa, ON H Oldsmobile MPV 6 Suburban 2 Moraine, OH J GMC Bus* 7 Motor Home Chassis 3 Detroit, Ml K GMC MPV 8 Utility (Blazer/Jimmy) 4 Scarborough, ON N Chevrolet MPV 9 Extended Cab/ 5 London, ON T GMC Truck Extended Van 7 Lordstown, OH * Van seating exceeds 8 Shreveport, LA 10 passengers Engine Type and Make Line and Chassis Type GVWR/BRAKE SYSTEM Chassis Code Producer Type RPO Code GVWR Range Brake System Code Line Type A CPC 2.5L L4 EFI L38 B 3001-4000 Hydraulic C Conventional Cab 4x2 B CPC 4.3L V6EFI LU2 C 4001-5000 Hydraulic R Conventional Cab 4x2 C CPC 6.2L V8 Diesel LH6 GDEF 6576000000001111----7689000000000000 HHHHyyyyddddrrrraaaauuuulllliiiicccc DGVKP CCFMVoaooilrnnniwtvvaaeeryrnnd ttT iiCoorunnocaankllt rCCoaalob 44444xxxxx24424 EHKJ CPCCCC-PPPNCCCorth 8.S252...L507LLVL V8VL 488D EEEieFFFsIIIel LLLLON0L4S38 H 9001-10,000 Hydraulic S Sm Conventional Cab 4x2 N CPC 7.4L V8 EFI L19 J 10,001-14,000 Hydraulic T Sm Conventional Cab 4x4 R CPC 2.8LV6EFI LL2 K 14,001-16,000 Hydraulic ML SSmm VVaann 44xx42 Z CPC 4.3L V6 EFI LB4 H Chassis Cutaway 4x2 F8850 Figure 3—Vehicle Identification Number size and recommended inflation pressures. On C/K and R/V trucks, M vans and G vans, the MFD. BY GENERAL MOTORS CORPORATION certification label is located on the trailing edge of the 19 I 2/86 driver’s door. On S/T trucks, it is located on the door anm Mum HIT MW* M lock pillar on the driver’s side. The label for Forward Ura/fntf 4649/21 OS P2110905//97553R15 — P26m0M/7B5R 8015 Control models is shipped separately and installed by Ml 15 X 6 JJ ^ m i5«fau m/ift CeU 35/241 ^ f » 35/wr the body manufacturer. WAX TIM ENGINE IDENTIFICATION i X4T NUMBER ALL APPLICABLE FEDE- |Cl.TSAFETY STANDARDS IN EFFECT MANUFACTURE SHOWN ABOVE. Refer to figures 5, 6, 7, 8 and 9 to determine the 100001 MPV location of the engine identification number. THIS VtMCli miHH FM 1000/453 IBS. PATUMO SEE OWNER’S MANUAL FOR ADDITIONAL INFORMATION F0597 Figure 4—Certification Label based on all factory installed equipment on the vehicle. The payload rating is reduced if any accessories or other equipment is added to the vehicle after final date of manufacture. The weight of these items should be determined and deducted from the payload rating. The vehicle may also have a GCWR (Gross Combi­ nation Weight Rating). The GCW (Gross Combination Weight) is the total weight of the loaded tow vehicle (including passengers) and a loaded trailer. The tires on the vehicle must be the proper size and properly inflated for the load being carried. The vehicle certification label shows the originally equipped tire GENERAL INFORMATION OA-3 TRANSMISSION IDENTIFICATION NUMBER Refer to figures 10 through 13 for determining trans­ mission identification numbers and code meanings. MODEL REFERENCE Refer to figures 14 through 19 for determining the vehicle model. C, R, and S models are two wheel drive. K, V, and T models are four wheel drive. METRIC FASTENERS The vehicle models are primarily dimensioned in the metric system. Many fasteners are metric and are very close in dimension to well-known customary fasteners in the inch system. It is most important that replace­ ment fasteners be of the correct nominal diameter, thread pitch and strength. Original equipment metric fasteners (except “beau­ ty” bolts, such as exposed bumper bolts, and cross recess head screws) are identified by a number mark­ ing indicating the strength of the material in the fasten­ er as outlined later. Metric cross recess screws are identified by a Posidriv or Type 1A shown in figure 20. Either a Phillips head or Type 1A cross recess screw­ driver can be used in Posidriv recess screw heads, but Type 1A cross recess screwdrivers will perform better. NOTICE: Most metric fasteners have a blue color coating. However, this should not be used as positive identification as some fasteners are not color coated. General Motors Engineering Standards, along with other North American Industries, have adopted a por­ Figure 6—2.8L Engine I.D. Location tion of the standard metric fastener sizes defined by ISO (International Standards Organization). This was size. For example, the customary 1/4-20 and 1/4-28 done to reduce the number of fastener sizes used and screws are replaced by the metric M6.X1 screw which yet retain the best strength qualities in each thread has nearly the same diameter and has 25.4 threads I.D. I.D. (Optional Location) F7552 Figure 7—4.3L Engine I.D. Location OA-4 GENERAL INFORMATION 1. Engine I.D. 2. Engine I.D. (Optional Location) F7553 Figure 8—5.0L, 5.7L, 7.4L Engine I.D. Location Figure 9—6.2L Diesel Engine I.D. Location per inch. The thread pitch is in between the customary FASTENER STRENGTH coarse and fine thread pitches. IDENTIFICATION Metric and customary thread notation differ slightly. The difference is shown in figure 21. Most commonly used metric fastener strength proper­ ly classes are 9.8 and 10.9 with the class identification embossed on the head of each bolt. Customary (inch) strength classes range from grade 2 to 8 with radial line identification embossed on each bolt head. Mark-