ISUZU 2003 User Manual
Body Builders Guide
I
Body Builders Guide
General Motors Isuzu Commercial Truck, LLC
(GMICT) and American Isuzu Motors Inc.
Is striving to provide you with the most upto-date and accurate information possible.
If you have any suggestion to improve the
Body Builder's Guide, please call GMICT
Application Engineering. In the West Coast
call 1-562-229-5314 and in the East Coast
call 1-404-257-3013
Notice of Rights
All rights reserved. No part of this book may be
reproduced or transmitted in any form or by any
means, electronic, mechanical, recording or
otherwise, without the prior written permission.
Notice of Liability
All specifications contained in this Body Builders Guide
are based on the latest product information available
at the time of publication. The manufacturer reserves
the right to discontinue or change at anytime without
prior notice, any parts, material, colors, special
equipment, specifications, designs and models.
Made and printed in the USA.
II
Contents
Introduction
FMVSS
EPA Requirements
Installation of Body & Special Equipment
Clearances
Body Installations
Prohibited Attachment Areas
Subframe Mounting
Crew Cab Body/Frame Requirements
Modification of the Frame
Fluid Lines
Electrical Wiring & Harnessing
Maximum Allowable Current
Exhaust System
Fuel System
Rear Lighting
Servicability
Wheelbase Alteration
Hydraulic Brake System
Body Application Summary Chart
NPR, NPR HD/W3500 W4500 Gas
NPR, NPR HD/W3500 W4500 Diesel
NQR/W5500 Diesel
NPR HD, NQR/W4500 W500 Crew Cab Diesel
FRR/WT
Mechanical & Cab Specifications
Engine Horsepower & Torque Chart
GVW/GCW Ratings
Rear Frame Height Chart
Clutch Engagement Torque
Paint Code Chart
N/W Series Towing Procedure
*
FRR/WT Series Towing Procedure
FSR, FTR & FVR Series Towing Procedure
Weight Distribution
Glossary of Dimensions
Weight Distribution Formulas
Recommended Weight Distribution
Trailer Weight
Performance Calculations
Highway Limits
Federal Bridge Formula Table
Commodity & Material Weights
Approximate Weight of Commodites & Materials
Vehicle Specifications Index
NPR, NPR HD/W3500 W4500 Gas
NPR, NPR HD/W3500 W4500 Diesel
NQR/W5500 Diesel
NPR, NPR HD NQR/W4500 W500 Crew Cab Diesel
FRR/WT
FSR, FTR & FVR
*
NPR, NPR HD/W3500 W4500 Gas Cab Chssis Electrical
NPR, NPR HD NQR/W3500 W4500 Diesel Cab Chssis Electrical
NPR HD NQR/W4500 W500 Crew Cab Electrical
FRR, FSR, FTR & FVR Cab Chassis Electrical
*
*Note: 2002 FSR, FTR and FVR
Weight Distribution Concepts
Weight Restriction
Gross Axle Weight Rating
Weighing the Vehicle
Tire Inflation
Center of Gravity
III
IV
Introduction
This guide has been provided as an aid to final stage manufacturers in determining conformity to the applicable
Emission Control and Federal Motor Vehicle Safety Standards. Final stage manufacturers should maintain current
knowledge of all Emission Regulations and Federal Motor Vehicle Safety Standards and be aware of their specific
responsibility in regards to each standard.
Any manufacturer making material alterations to this incomplete vehicle during the process of manufacturing the
completed vehicle should be constantly alert to all effects, direct or indirect, on other components, assemblies or
systems caused by such alterations. No alterations should be made to the incomplete vehicle that directly or
indirectly results in any either component, assembly or system being in nonconformance with applicable Emission
Regulations or Federal Motor Vehicle Safety Standards.
General Motors Isuzu Commercial Truck, LLC (GMICT) and American Isuzu Motors Inc. will honor its warranty
commitment (for the cab-chassis only), to the ultimate consumer, provided: (1) the final stage manufacturer has
not made any alterations or modifications which do not conform to any applicable laws, regulations or standards, or
adversely affect the operation of the cab-chassis; and (2) the final stage manufacturer complied with the instructions contained in this guide with respect to the completion of the vehicle. Otherwise, the warranty becomes the
responsibility of the final stage manufacturer.
The final stage manufacturer is solely responsible for the final certification of the vehicle and for compliance with
Emission Control and Federal Motor Vehicle Safety Standards. The information contained in this guide has been
provided for the final stage manufacturer’s information and guidance.
This guide contains information pertaining to the NPR/W Gas, NPR/W Diesel, NQR/W Diesel, NPR HD/NQR/W
Diesel Crew Cab and FRR/WT Series Chassis Cab and Janesville assembled FSR, FTR and FVR Chassis Cab.
Following is a list of Federal Motor Vehicle Safety Standards applicable to those vehicles with a GVWR greater than
10,000 lbs. Please refer to the following chart.
V
FMVSS Chart
NOTE: This chart is only a guide, for complete information please refer to "Document for Incomplete Vehicle”
provided with each chassis.
Chart Legend:
A Incomplete vehicle; when completed will conform providing no alterations have been made affecting items
covered by FMVSS regulations and "Document for Incomplete Vehicle.
B Incomplete vehicle; when completed by the final manufacturer will conform providing it is completed in
compliance with FMVSS regulations and "Document for Incomplete Vehicle."
+ Meets Canadian Motor Vehicle Safety Standards bearing same FMVSS number.
3 Canadian MVSS only.
4 Not applicable to truck or bus.
5 Not applicable to trucks with a GVWR greater than 10,000 LBS.
VI
EPA Requirements
NPR/W Gas, NPR/W Diesel, NQR/W Diesel, NPR HD/NQR/W Diesel Crew Cab and FRR/WT Series Chassis Cab
To assure that U.S.A. and Canada Emission Requirements are met, this Incomplete Vehicle must be completed in
strict accordance with all instructions contained in this document, especially the following instructions which relate
to:
A. Exhaust emission related components
B. Noise emission related components
C. Labels
[A] EXHAUST EMISSION RELA TED COMPONENTS
Compliance of this vehicle with EP A, California and Canada Requirements will be maintained providing
no alterations are made to the components or systems identified below:
1) DIESEL VEHICLES 2) GASOLINE VEHICLES
Injection Pump Vehicle Control Module (VCM)
Injector and High Pressure Lines Fuel Management System
Turbocharger Air Induction System
Charge Air Cooler and Charge Ignition System
Air Cooler Hoses Catalytic Converter System
Engine Control Module (ECM) Positive Crankcase V entilation System
Engine Speed Sensor Exhaust Gas Recirculation System
Engine Coolant T emperature Sensor Evaporative Emission Control System
Intake Manifold Miscellaneous Items Used in Above Systems
Catalytic converter and its location
V ariable swirl system
Exhaust Gas Recirculation System
ADDITIONAL CANADA MOTOR VEHICLE SAFETY ST ANDARD
CMVSS NO. 1 101-EMISSION DEVICE
CMVSS NO. 1 102-CRANKCASE EMISSION (GASOLINE ENGINE ONLY)
CMVSS NO. 1 103-EXHAUST EMISSIONS
CMVSS NO. 1 104-OPACITY (DIESEL ENGINE ONL Y)
CMVSS NO. 1 105- EVAPORATIVE EMISSION (GASOLINE ENGINE ONLY)
[B] NOISE
Compliance of this vehicle with EP A and Canada requirements will be maintained providing no
alterations are made to the components or systems.
CMVSS NO. 1 106-NOISE
This incomplete vehicle, when completed, will conform to the above standards except CMVSS-1106 providing no
alterations are made which effect the function, physical or mechanical properties, environment, locations or vital
spatial clearances of the components identified below:
* Engine assembly
Exhaust emission control system
P.C.V. system (if equipped)
* Intake system
* Exhaust system
Fuel system (if equipped)
* Transmission assembly
* Axle
* Tires
* Fan and drive
Diesel fuel injection controls (if equipped)
Turbocharger and associated controls (if equipped)
* Catalytic converter and its location
V ariable swirl system (if equipped)
VII
Conformity with CMVSS 1 106 is not determined solely by the design of the incomplete vehicle. When completed, it
should conform to CMVSS 1 106 providing no alterations are made to the noise attenuation components identified
thus * in the above list.
[C] LABELS
The Emission control related information labels which are permanently affixed are required by government
regulation and must not be obstructed from view or defaced so as to impair its visibility or legibility .
P A R T 3 : Radio Noise
CANADIAN RADIO INTERFERENCE REGULA TIONS
[A] The following statement is applicable to NPR/W Series Chassis-Cab (Gasoline Engine Only).
This incomplete Vehicle, when completed, will conform to the above regulations providing no alterations or substitutions are made which affect any parts or components identified below:
A. Distributor
B. Ignition Wires
C. Spark Plug Wires
FSR, FTR & FVR
U.S. ENVIRONMENT AL PROTECTION AGENCY AND STA TE OF CALIFORNIA EMISSION REQUIREMENTS
To assure that EPA and California Emission Certificate Requirements are met, this incomplete vehicle must be
completed in strict accordance with all instructions contained in this document, especially the following instructions
which relate to:
A. Exhaust emission related components
B. Labels
[D] EXHAUST EMISSION RELATED COMPONENTS
Compliance of this vehicle with EP A and California Certification Requirements will be maintained providing
no alterations are made to the components or systems identified below:
1. DIESEL VEHICLES
Injection Pump
Injector and High Pressure Lines
Turbocharger
Charge Air Cooler and Charge Air Cooler Hoses
Engine Control Module (ECM)
Engine Speed Sensor
Engine Coolant Temperature Sensor (6HE1-TC only)
Intake Manifold
Catalytic converter and its location (6HE1-TC only)
Air cylinder for variable swirl system (6HE1-TCS only)
[E] LABELS
The Emission control related information labels which are permanently affixed are required by government regula-
tion and must not be obstructed from view or defaced so as to impair its visibility or legibility .
VIII
CANADIAN MOTOR VEHICLE SAFETY STANDARDS
CMVSS NO. 1 101-EMISSION DEVICE
CMVSS NO. 1 103-EXHAUST EMISSIONS
CMVSS NO. 1 104-OPACITY
CMVSS NO. 1 106-NOISE
This incomplete vehicle, when completed, will conform to the above standards except CMVSS 1106 providing no
alterations are made which affect the function, physical or mechanical properties, environment, locations or vital
spatial clearances of the components identified below:
Engine assembly*
Exhaust emission control system
P.C.V . system
Intake system*
Exhaust system*
Fuel system
Transmission assembly*
Axle*
Tires*
Fan and drive*
Diesel fuel injection controls
Turbocharger and associated controls
Catalytic converter and its location (6HE1-TC only) *
Air cylinder for variable swirl system (6HE1- TCS only)
Conformity with CMVSS 1 106 is not determined solely by the design of the incomplete vehicle. When completed, it
should conform to CMVSS 1 106 providing no alterations are made to the noise attenuation components identified
thus * in the above list.
Compliance of this vehicle with EP A and California Certification Requirements will be maintained providing no
alterations are made to the components or systems identified below:
Air Inlet System
Diesel Fuel Injection Controls
Engine Assembly with all Components of Exhaust Emission Control System
Exhaust System
Fuel System
Turbocharger and Associated Controls
IX
Installation of Body & Special Equipment
Installation of Body
&
Special Equipment
April 2002 1
Installation of Body & Special Equipment
Clearances
Engine
At least 1.6 inch clearance should be maintained around the engine. No obstacles should be added in front of the
radiator or intercooler.
1.6 Inch
Clearance
1.6 Inch
Clearance
Engine
1.6 Inch
Clearance
Transmission
The transmission is removed from the rear. Enough clearance must be provided to allow rearward movement of the
transmission assembly. Clearance should be sufficient to allow 5 to 6 inches unrestricted movement of the
transmission assembly. In addition, provide at least 2 inches clearance around the control lever on the side of the
transmission to allow free movement without any binding.
5-6 Inch
Engine
Clearance
Transmission
At least 6 inches clearance should be maintained above the transmission to allow easy removal of the upper cover
for manual transmissions. At least 2 inches clearance should be maintained above the automatic transmission to
allow for transmission removal.
5.9
Inches or More M/T
(150)
2.0
Inches or More A/T
(58)
Transmission
2 April 2002
Installation of Body & Special Equipment
Front and Center Propeller Shafts
At least 1.25 inch clearance should be maintained around front and center propeller shafts.
1.25 Inches or more
1.25 Inches or more
Front Propellar Shaft
Rear Propeller Shaft
With the rear springs at maximum deflection, at least 1.25 inch clearance should be provided over the rear propeller
shaft.
1.25 Inches or more
Front Propellar Shaft
Exhaust System
If flammable materials such as wood are used in the body, provide at least 3.9 inches clearance between the body
and any parts of the exhaust pipe, muffler and catalytic converter. If it is impossible to maintain this minimum
clearance, use a heat shield. Also use a heat shield if an oil pump or line is located above the exhaust pipe, muffler
or catalytic converter.
Tool Box
1.25 Inches or more
3.9 Inch
Clerance
Oil Pump
Heat Shield
Front Propellar Shaft
April 2002 3
Exhaust Pipe
Muffler
Installation of Body & Special Equipment
Rear Wheel and Axle
The design and installation of the body should allow sufficient clearance for full vertical movement of the rear wheels
and axle when the vehicle travels over rough or unlevel surfaces.
Rear of Body
*NOTE: For recomended clearances
please refer to the Rear Axle Chart in
each models respective section.
Normal Rear
Axle Center Line
Rear Wheels
Over High Spot
Rear Wheels
Over Obstacle
Other Clearances
Transmission control cable may be broken if it is bent by or interferes with the body and its fixtures. To prevent this,
1 inch minimum clearance should be provided. When cable is detached for body mounting, be sure not to bend the
cable.
Accessibility to the grease nipple on the rear spring bracket/shackle should be provided so that serviceability with a
grease gun is not hampered.
MINIMUM
PARTS CLEARANCE LOCATION
Brake Hose 6.7 in. Axle side
1.6 in. Frame side
Parking Brake Cable 1.2 in. -------Fuel Hose 1.6 in. -------Shock Absorber 2.4 in. Axle Side
1.2 in. Frame Side
4 April 2002
Installation of Body & Special Equipment
Body Installation
Chassis
To maintain the performance of the truck chassis, either a side member or subframe should always be used for body
mounting. Body mounting with low rigidity will often adversely affect riding comfort.
Special Equipment on the Chassis
When installing special equipment on the chassis, extra consideration must be given to the weight and construction
of the equipment to assure proper distribution of the load. Localization of the load should be prevented. All special
equipment should be properly secured into position. We recommend the use of subframe members when installing
special equipment.
Subframe Design and Mounting
The subframe assembly should be mounted as close to the cab as possible. It should be contoured to match the shape
and dimensions of the chassis frame as closely as possible.
Rear End of the Cab
April 2002 5
Installation of Body & Special Equipment
Subframe Contour
Contouring of the front end of the subframe members as shown in the three illustrations below will prevent stresses
from being concentrated on certain areas of the chassis frame.
1
A
3
A
Wooden subframe
B
B
45
o
H
H
Steel subframe
2
Steel subframe
A
B
Drawing A B
1 0.2 in. H
2 0.2 in. H or more
3 H H or more
H
2 ~ H
3
When using a steel subframe, do not close the end of the subframe.
Steel subframe
Chassis frame
6 April 2002
Installation of Body & Special Equipment
Prohibited Attachment Areas
Do not attach the subframe with a bolt on bracket to the chassis frame at the points indicated by shading in the following
illustrations.
1. At the front end of the subframe. The attaching bolt or bracket must be at least 2 inches behind the kick
up point of the subframe.
2. Within 8 inches of bends in the chassis frame or the attachment points of any cross members.
3.3
8 in. 8 in
6.1
8 in. 8 in
3.1
Do not attach in these areas.
3.12.9
2.8
April 2002 7
Installation of Body & Special Equipment
Subframe Mounting
Bracket Installation
Mounting brackets should be clamped to the chassis frame using bolts. For proper positions in which to install the
bolts, refer to the preceding section and the section “Modifications to the Chassis Frame.”
Bolster
Subframe member
Cushioning material
Chassis frame
Bracket
Cushioning material
Chassis frame
U-bolt Installation
When U-bolts are used to retain the subframe, reinforcement blocks must be installed in the frame members. This
will prevent distortion of the frame flange as they are tightened. The drawing indicates the correct placement of
reinforcement blocks. If you use wood blocks, be sure that there is sufficient clearance between them and any parts
of the exhaust system.
If any fluid lines or electric cables are located near the reinforcement blocks, you must provide at least 0.4 inch
clearance between rigid or stationary portions, and at least 1.6 inch between moveable or flexible portions of the lines.
Reinforcement block
(Reinforcement blocks should be mounted
securely in installed position)
For the installation positions of the U-bolts, refer to “Prohibited Attachment Areas.”
8 April 2002
Installation of Body & Special Equipment
Crew Cab Body/Frame Requirement
The Crew Cab NPR HD/W4500 and NQR/W5500 will be available in two wheelbases, 150 and 176 inches. Effective
CA will be 84.7 and 110.7 inches. On this model chassis General Motors Isuzu Commercial Truck, LLC (GMICT)
and American Isuzu Motors Inc. will require that the body installed on the chassis have an understructure
manufactured with any of the following structural steel "C" channels:
4"x1-5/8", 7.25 lbs/ft = ok
5"x1-3/4", 6.7 or 9.0 lbs/ft = ok
6"x2", 8.2, 10.5 or 13.0 lbs/ft = ok
Modification of the Frame
Modification of chassis frame should be kept to an absolute minimum. Modification work should be performed
according the instructions in the following paragraphs.
When modification is complete, chassis frame members should be carefully inspected to eliminate the possibility of
any safety-related defects.
NOTE: PLEASE REFER TO NOTES ON CHASSIS FRAME MODIFICATION WITH ANTILOCK BRAKES ON PAGES 27 AND 28
Working on Chassis Frame
The chassis frame is designed and built with consideration for proper load distribution. Sufficient physical strength
is provided when the load is evenly distributed. Installation of special equipment on the chassis frame can cause
variations in load distribution. If even distribution of load is not kept in mind when the equipment is installed, localization
of stresses on specific areas of the frame could cause cracking of the chassis frame members or other problems,
even if the total weight of the equipment is within the design limit.
The chassis frame is designed as an integral unit. Therefore, we do not recommend cutting the chassis frame
under any circumstances.
Drilling and Welding
IMPORTANT NOTE
For vehicles equipped with electronic or hydra-matic
transmissions electric arc welding must be done with the
negative battery cable disconnected.
1. Do not drill or weld in the shaded portions of the chassis frame members. Do not weld with 0.8 inch from th edges
of any existing holes.
2. Hold the length of any welding beads within 1.2-2.0 inch. Allow at least 1.6 inch between adjacent welding beads.
3. All holes must be drilled. Do not use a torch to make any holes.
4. All riveting must be done with cold rivets. Do not use hot rivets.
5. The flange of the chassis frame must not be cut under any circumstances.
6. The subframe must be attached to the chassis frame with bolts. Do not weld.
B
A
Dimensions: A - not more than 0.51 in. in diameter
C
April 2002 9
B - must be more than 0.8 in.
C - must be more than 1.0 in.
Installation of Body & Special Equipment
Reinforcement of Chassis Frame
Reinforcements must be installed to prevent the considerable variation in the section modulus. They must be welded
so as to avoid localized stresses.
The frame of the NPR/W3500, NPR GAS/W4500 and NQR/W5500 is made of SAPH440 mild steel. The frame of
the FRR is made of HT540A. See the FSR, FTR and FVR section for frame material specifications.
The drawings below illustrates correct and incorrect methods of frame reinforcement.
Welding
1. Keep reinforcement plates and chassis frame free from moisture and water.
2. Avoid cooling with water after welding.
3. Use a suitable means to protect pipes, wires, rubber parts, leaf springs, etc. against heat and
affect of sputtering.
4. Remove fuel tank assembly when welding portions near the fuel tank.
5. Remove coat of paint completely when welding painted areas.
SATISFACTORY
o
45
Fluid Lines
Reinforcement
Plug weld or rivet
UNSATISFACTORY
Frame rail
Frame rail
Reinforcement
Welding is prohibited
Do not disturb the layout of any brake lines or fuel lines unless absolutely necessary. When modification is needed,
follow the instructions below carefully to ensure safety. Brake fluid lines must not be cut and spliced under any
circumstances. We do not recommend the cutting or splicing of any fuel lines, but if it is absolutely necessary, be
sure that the correct fitting and tools are used to form the joint, and then pressure test the joint. Steel lines are metric
sizes.
Preparation of Additional Lines
1. Where possible, use only genuine Isuzu lines as supplied by authorized Isuzu dealers.
2. Use the correct metric flaring and bending tools to form the lines.
3. Avoid repeated bending. Do not use heat for flaring and bending the lines. Before and after
forming the new lines, examine them carefully for scratches, distortion, dents and the presence
of any foreign matter.
10 April 2002
Installation of Body & Special Equipment
Installation of Additional Lines
Install new lines away from adjacent parts and away from any sources of heat.
1. A minimum clearance of 0.4 inch must be maintained between lines. Where necessary, clip the
lines into position in order to maintain this minimum clearance.
2. Minimize any crossing between lines. If a crossing is unavoidable, use the following procedure:
a. At least 0.4 inch clearance should be maintained between lines at the crossing point.
b. If the 0.4 inch clearance cannot be maintained, or if the lines are subject to vibration, clip
them securely.
3. Plan the bends and clipping points of the lines to minimize vibration and the resulting fatigue.
4. Use rust-proofed clips and apply vinyl coating to the portions of the lines to be clipped.
5. Install new lines in positions where they are protected against water, dirt, grit, sand, rocks and
other foreign matter that can come from above or below, or can be flung up by the wheels.
Lines
Clip
0.4 in. or more
Vinyl
Clip
Electrical Wiring and Harnessing
To increase the reliability of the wiring, all frame harnesses are covered with corrugated vinyl tubing. The following instructions apply to extending or modifying these harnesses. See the Electrical Section for information on
commonly used circuits in the NPR, NQR, FRR and W-Series. The FSR, FTR and FVR wiring information can
be found in the service manuals.
Wiring
1. Most wiring connections on Isuzu vehicles are made with terminals. We recommend the use of
terminals when splicing cables and wires.
2. When splicing, use new wire of the same gauge, and do not make splices inside the corrugated
tubing.
3. When making connections to the end of the harness, make sure the connections are electrically
perfect. Use insulating tape as needed to prevent the entry of water, which results in short
circuits and/or corrosion.
4. When making new circuits, or modifying circuits already installed, make the cables only just taut
enough to remove any slack. Use clips or grommets where required to protect cables from heat
or sharp edges. When cables must run near the exhaust system, see the instructions in the
“Exhaust System” section.
5. Always use rustproof clips, and apply vinyl coating to that portion of the clips in direct contact
with the harnesses. No scotch clips or connectors.
6. To minimize the vibration of the harness, clipping points should be set up according to the table.
Harness Diameter Clip Distance
less than 0.2 in. less than 11.8 in.
0.2 in. ~ 0.4 in. approx. 15.7 in.
0.4 in. ~ 0.8 in. approx. 19.7 in.
April 2002 11
Installation of Body & Special Equipment
7. When changing the length of the battery cable, do not cut or splice the existing cable. Make up a
new cable of the correct length and wire gauge for the load and distance, without splices.
8. When using connectors, use a socket (female) connector on the electrical source side and a
plug (male) connector on the electrical load side to lower the possibility of a short circuit when
disconnected.
9. When connecting cables to moving or vibrating parts such as the engine or transmission, be
sure to maintain sufficient slack in the wiring to absorb the vibration. Follow the example of
existing cables connected by Isuzu. Keep flexible cables clear of other parts.
10. Do not use vinyl tape in the engine compartment. The heat will tend to make it peel off. Use
plated steel clips coated with rubber or vinyl.
Vinyl tube
Clip
Harness
Direct contact*
SATISFACTORY
Rubber grommet
Steel plate
SATISFACTORY
Electric wire
* Cables should not be in contact with sharp edges or pierced holes.
Harness
SATISFACTORY UNSATISFACTORY
UNSATISFACTORY
UNSATISFACTORY
Harness*
The harness receives
the adverse affect of
dirt, grit, or water
* Harnesses should not be installed on inside lower face of the chassis frame.
* Harnesses should not be taped to fuel lines or other lines. A sufficient clearance should be maintained between
harness and pipe lines.
Line
When parallel: 0.4 in. or more
When across: 0.8 in. or more
Harness
12 April 2002
UNSATISFACTORYSATISFACTORY
Taping*
Installation of Body & Special Equipment
Wire Color Code
The electrical circuits of the N/W and FRR/WT Series Chassis Cab are connected with low-voltage stranded wire for
automotive applications. The color coding standards are as follows for the N/W and FRR/WT Series Chassis Cab.
Refer to FSR, FTR and FVR service manual for those vehicle wiring color codes.
(1) Black B Starter circuits and grounds
(2) White W Generator (alternator) circuit
(3) Red R Lighting circuit
(4) Green G Signal circuit
(5) Yellow Y Instrument circuit
(6) Brown Br Accessory circuit
(7) Light Green Lg Other circuit
(8) Blue L Windshield wiper motor circuit
Maximum Allowable Current
Harness Design AWG No. of wires/ Cross sectional Maximum allowable
Diameter (mm) equivalent wire diameter (mm) area (mm2) current (Amps)
100 00 217/0.80 109.1 363
85 0 169/0.80 84.96 305
60 1 127/0.80 63.84 248
50 1 108/0.80 54.29 223
40 1 85/0.80 42.73 191
30 2 70/0.80 35.19 171
20 4 41/0.80 20.61 123
15 6 84/0.45 13.36 93
8 8 50/0.45 7.952 68
5 8 65/0.32 5.228 51
3 12 41/0.32 3.297 39
2 14 26/0.32 2.091 29
1.25 16 16/0.32 1.287 21
0.85 18 11/0.32 0.8846 17
0.5 20 7/0.32 0.5629 13
Reference: The values given in the “maximum allowable current” column are based on the ambient temperature
condition of 104o F with temperature increase of 104o F.
Electrical System Modifications
Modifications/add-on wiring must be carefully reviewed to ensure compatibility with the base vehicle wiring by
reviewing system schematics, wire routing paths, harness connections, etc. Due to the wide range of
modifications that may be required for vocational needs, it is not feasible for the O.E.M. to take into account all
potential revisions. For this reason, any person modifying existing vehicle wiring must assume responsibility that
the revisions have not degraded the electrical system performance. Any add-on wiring needs to be properly
fused and routed to prevent cut, pinch, and chafe problems, as well as avoid exposure to excessive heat. Care
must be exercised that existing vehicle interfaces do not have their current load capabilities exceeded, and that
the respective control devices are not overloaded. Added wire size should be at least as large as the wire to
which it is attaching in order for fuse protection to be maintained.
A Packard electric wiring repair kit is available through Kent-Moore (P/N J38125-B) (Phone # 1-800-345-2233)
This kit contains instructions, tools and components for making repairs to wiring harness components. This kit
would also greatly assist in accomplishing necessary add-on wiring such as body marker lamps, so that system
April 2002 13
Installation of Body & Special Equipment
reliability/durability is maintained.
Electrical wiring components can be obtained through your authorized Isuzu/GM dealers. Packard Electric
components are also available through Pioneer Standard Company (1-00-PACKARD). Pioneer may also be able
to assist in making necessary wiring additions by providing custom wiring stubs or jumpers to your specifications.
Exhaust System
Modification of the exhaust system should be avoided. If modifications are absolutely necessary, the following points
should be maintained.
1. Maintain the clearance specified in the table on the next page between all parts of the exhaust system and
any fuel lines, brake lines, brake hoses, electrical cables, etc. The exhaust outlet should not point toward
any of these parts.
CLEARANCE
Brake Lines 2.4 in. or more. (If the combined section of a group of parallel brake lines is
more than 7.8 in., a clearance of 7 in. or more should be provided.)
Flexible brake hoses 3.9 in. or more. (The temperature of flexible brake hoses should not exceed
158o F. If the highest temperature is not measurable, a clearance of more
than 15.7 in. should be maintained between the hoses and the exhaust
system.
Wiring harnesses and cables 3.9 in. or more.
Steel fuel lines 3.1 in. or more.
Rubber or vinyl fuel hoses 5.9 in. or more.
2. If a tool box is installed, it should preferably be made from steel. If a wooden tool box is
installed, at least 7.8 inches clearance should maintained between the tool box and any parts of
the exhaust system.
3. If the exhaust system is modified, it is the responsibility of those making the modification to
ensure that the noise level meets appropriate standards.
Fuel System
Relocation of the fuel tank, or installation of additional fuel tanks is not recommended. If modifications to the fuel
system are unavoidable, follow these recommendations:
1. Maintain adequate clearance between the fuel tank and any other device or structure.
2. Do no connect an additional fuel hose.
Rear Lighting
Brackets installed are temporary. Please do not use these brackets for body installation.
Serviceability
No matter what other modifications or changes are made, access to components requiring daily preventive
maintenance or other routine service must not be obstructed. This includes:
1. Inspection, filling and draining of engine oil and cooling water.
2. Inspection, filling and draining of transmission fluid.
14 April 2002
Installation of Body & Special Equipment
3. Adjustment, removal and installation of the fan belts.
4. Inspection, filling and removal of the battery and battery cover.
5. Inspection and filling of brake fluid.
6. Inspection and bleeding of the brake system and servo unit.
7. Maintenance of clearance for tightening of check bolt on brake safety cylinder.
8. Operation of the spare tire carrier, including mounting and dismounting of the spare tire.
9. Adjustment, removal and installation of distributor and/or cover.
WHEELBASE ALTERATION
With certain applications, it may become necessary to alter the wheelbase of the chassis. The next two sections
provide the suggested guidelines for accomplishing either shortening or lengthening of the wheelbase.
SHORTENING/LENGTHENING THE WHEELBASE WITHOUT ALTERING THE FRAME
Since the frame is an integral part of the chassis, it is recommended that the frame not be cut if it is possible to avoid
it. When shortening/lengthening the wheelbase on some models, it is possible to do so without cutting the frame. This
is possible on models which have a straight frame rail. If the chassis does not have a straight frame rail, it may still
be necessary to cut the frame. For instructions on shortening/lengthening these chassis, refer to the ALTERING THE
WHEELBASE BY ALTERING THE FRAME section of this book. Otherwise, the wheelbase may be shortened/
lengthened by removing the rear suspension, drilling new suspension mounting holes at the appropriate spot in the
frame, and sliding the rear suspension, suspension liner, and suspension crossmembers forward or aft. The
suspension and suspension crossmembers' rivet holes left in the frame rail flange must be filled with GRADE 8 bolts
and hardened steel washers at both the bolt head and nut, HUC bolts or GRADE 8 flanged bolts and hardened steel
washers at the nut. When shortening/lengthening the wheelbase in this manner, the following guidelines must be
adhered to:
1. All frame drilling must comply with the DRILLING AND WELDING section of this book.
2. All rivet holes left in the frame rail flange from the suspension and suspension crossmembers
must be either filled with GRADE 8 bolts and hardened steel washers at both the bolt head and
nut, HUC bolts or GRADE 8 flanged bolts and hardened steel washers at the nut.
3. The components required to be slid forward or aft are the suspension and suspension hangers,
suspension crossmembers and suspension frame liner.
ALTERING THE WHEELBASE BY ALTERING THE FRAME
Even on a straight frame rail, it may be desirable to cut the frame and lengthen or shorten the wheelbase rather than
simply sliding the rear suspension back or forward. The following section offers some guidelines and suggestions
for cutting and lengthening or shortening the frame.
GLOSSARY OF TERMS-CHASSIS WHEELBASE ALTERATION
CA - Length from back-of-cab to rear axle center line in inches.
AL - Added length (in case of a lengthened wheelbase). Difference between WB (new) and WB (old).
SL - Shortened length (in case of shortened wheelbase). Difference between WB (old) and WB (new).
April 2002 15
Installation of Body & Special Equipment
1. Determine the added length (AL) or shortened length (SL) required to lengthen or shorten chassis.
(For added wheelbase: New CA = CA + AL; For shortened wheelbase: New CA = CA - SL)
2. Obtain the material to be used as the insert for the lengthened wheelbase in the correct length (AL). The
insert must have the same cross sectional dimensions and yield strength as the original frame rail.
3. Divide the new CA by two (2). Measure (new CA)/2 from the center of the rear axle forward and mark this
point on the chassis frame (see figure below).
Cut Point
1/2 New CA
4. Cut the chassis frame at this point. If the wheelbase is to be lengthened, addition of the previously
obtained insert (of length AL determined in step 1) will be made at this time. If the wheelbase is to be
shortened, measure the distance (SL) forward of this cut and remove a length (SL) section from the
chassis frame (see figure below). Insure that an adequate area on the frame remains for the required
addition of the necessary reinforcements. These are the only suggested places for cutting the frame and
reinforcements but may be changed upon the advice of General Motors Isuzu Commercial Truck, LLC
(GMICT) and American Isuzu Motors Inc. Application Engineering.
Section to be Added
Cut Point
AL
Lengthening the Wheelbase
New CA
2
Second Cut Point
Section to be Removed
First Cut Point
SL
New CA
2
Shortening the Wheelbase
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Installation of Body & Special Equipment
5. When welding the insert (length AL for wheelbase lengthening) to the original frame rail, a continuous butt weld
must be used at the splices. When shortening the wheelbase, weld the ends of the chassis frame together with
a continuous butt weld over the junction of the frame ends. Weld both the inside and outside of the frame rails
using welding techniques prescribed by established welding standards (ref. SAE J1147) and in accordance with
this guide. An example of this weld is shown below.
BUTT WELD 100 % - Weld can be inside or outside
of member or, as shown, a combination of both
1.0 in. or more
1.0 in. or more
6. Determine the appropriate additional internal reinforcements which are required using this equation:
Reinforcement Length = AL + 6 x (original frame rail web depth).
The figure below shows how this reinforcement is to be placed over the extended or shortened section of the
frame rail.
D
AL3 x D 3 x D
6 x D + AL
Lengthened Wheelbase
3 x D
Shortened Wheelbase
3 x D
6 x D
D = Original frame rail web depth
The suggested cross section of this reinforcement is a snug fit inner channel. If the new wheelbase exceeds
the upper limit of the optional wheelbases of this model, i.e.; a “long bridge”, it may be necessary to use an “inverted
L” reinforcement in addition to the snug fit channel reinforcement (see figures below). Application Engineering should
be consulted for approval of such cases. It should be noted that these methods of reinforcements, and any other
methods which may be used, require a 45 degree angled cut at both ends to avoid stress concentrations in the frame
(note the figures under item 7).
OR
Snug fit inner channel with "Inverted L" for "Long Bridge" wheelbasesSnug fit inner channel
April 2002 17
Installation of Body & Special Equipment
7. The reinforcements must be fastened securely to only the web of the original chassis frame rail. The
reinforcement must be held rigidly in place using either HUC bolts, GRADE 8 bolts and hardened steel washers
at both the bolt head and nut, or GRADE 8 flanged bolts and hardened steel washers at the nut. Below are some
suggested bolt patterns. It should be noted that these bolt patterns must not align the bolts vertically, i.e.: the bolt
pattern must be staggered.
8. Lengthening the frame will also require extending the brake lines, basic chassis electrical harnesses, excluding
ABS wiring harness. It is recommended that the original brake lines be removed and replaced with brake lines
of the same diameter as the original lines and of the appropriate length. The electrical harness must be extended
in accordance with the ELECTRICAL WIRING AND HARNESSING section of this book.
9. The propeller shafts’ overall length will also need to be lengthened or shortened. If the extension is within the limits
of the optional wheelbases of the respective model, the exact propeller shaft lengths and angles are given on or
about Page 12 of the respective sections of this book. If the modified wheelbase exceeds the optional wheelbases
of the respective model, the following guidelines must be adhered to:
A. Propeller Shaft Length
The maximum propeller shaft lengths (pin to pin) for the respective models are shown in the table below.
NPR NPR GAS NQR FRR
Propeller
Shaft 3.25 3.0 3.0 4.0
Diameter (in)
Maximum
Propeller Shaft 50.8 50.8 50.8 62.0
Length (in)
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Installation of Body & Special Equipment
B. Propeller Shaft Angles
The maximum propeller shaft angles, with respect to the previous shaft, are shown in the table below.
NPR/W NPR/W GAS NQR/W FRR/WT
Maximum Propeller
Shaft Angle 5.7
o
5.1
o
5.7
o
5.5
o
C. The propeller shaft angles must be designed such that the angles will cancel to avoid propeller shaft whip.
D. The propeller shaft yokes must be assembled such that the propeller shaft yokes are “in phase.” “In
phase” means that the yokes at either end of a given propeller shaft assembly are in the same plane.
10. Extending the frame will also require relocation and/or addition of crossmembers. If the extension is within the
limits of the optional wheelbases of the respective model, the exact cross member locations and dimensions
are given in the respective model sections of this book. If the modified wheelbase exceeds the optional
wheelbases of the respective model, the following guidelines must be adhered to:
A. The cross member location will largely be determined by the propeller shaft lengths and where the center
carrier bearing locations are for the propeller shaft assembly.
B. A cross member must be located at the front and rear spring hangers of the rear suspension (refer to the
appropriate section of this book to see where these suspension cross members are to be located).
C. The cross member must be constructed such that it supports both the upper and lower flange on each
frame rail (see drawing below). A cross member such as the one below may be constructed, or Isuzu
cross members may be obtained from your Isuzu parts dealer.
Additional crossmember
Frame rails
April 2002 19
Installation of Body & Special Equipment
D. The maximum distance between crossmembers for the respective models is given in the table below.
NPR/W NPR/W GAS NQR/W FRR/WT
Maximum Distance 35.7 35.7 35.7 49.8
Between Cross
Members (in)
E. The drilling for any additional holes in the frame rails must comply to the DRILLING AND WELDING
section of this book.
11. All other aspects of lengthening or shortening the wheelbase must comply with the applicable section of
this Body Builder's Guide. For special applications and longer than recommended body lengths, GMICT
Application Engineering must be consulted for approval. In the West Coast call 1-562-229-5314 and in
the East Coast call 1-404-257-3013
12. Please contact applications engineering for guidelines on N/W SERIES CHASSIS frame modifications when
the vehicle is equipped with an Antilock Brake System.
FRR SERIES CHASSIS
Please contact applications engineering for guidelines on FRR SERIES CHASSIS frame modifications when the
vehicle is equipped with an Antilock Brake System
FSR FTR FVR
WHEN MAKING WHEELBASE MODIFICATIONS TO THE 1997, MODEL YEAR AND ABOVE FSR, FTR, AND
FVR HYDRAULIC BRAKE CHASSIS AND AIR BRAKE CHASSIS THE FOLLOWING SHOULD BE STRICTLY
OBSERVED.
13. The Crew Cab NPR HD/W4500 and NQR/W5500 will be available in two wheelbases, 150 and 176 inches.
Effective CA will be 84.7 and 110.7 inches. On this model chassis General Motors Isuzu Commercial Trucks
will require that the body installed on the chassis have an understructure manufactured with any of the following
structural steel "C" channels:
4"x1-5/8", 7.25 lbs/ft = ok
5"x1-3/4", 6.7 or 9.0 lbs/ft = ok
6"x2", 8.2, 10.5 or 13.0 lbs/ft = ok
HYDRAULIC BRAKE SYSTEM
1. BEFORE WORK BEGINS
As with any electrical work on the chassis the battery should be disconnected before electrical work is started.
2. ABS PROGRAM
The antilock brake system (ABS) computer will hold its codes when disconnected and reprogramming as a result
of battery disconnection will not be necessary. If the wheelbase is changed the trim level of the ABS system
must be readjusted per the instructions in the service manual. An Authorized Isuzu dealer should do this
reprogramming using appropriate tools.
For your reference and to help you determine if the system needs to be reprogrammed the following provisions
apply to all ABS systems with hydraulic brakes. The ABS module has four (4) programs: A, B, C, and D. These
programs are tied to the wheelbase and axle combination of the chassis. (The axle and wheel base codes can be
found on the passenger’s visor.)
A is for the FL1 axle and covers wheelbase from 140 (FQT), 158 (EG5), 170 (EH8) inches.
B is for the FL2 axle and covers wheelbase from 140 (FQT), 158 (EG5), 170 (EH8), 188 (EK8), 200 (EM2)
inches.
20 April 2002
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