Page 2593 of 3061
PREPARATION
RSU-3
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PREPARATION
Commercial Service ToolINFOID:0000000003532654
Tool nameDescription
Power tool• Removing wheel nuts
• Removing brake caliper assembly
• Removing rear suspension component
parts
PBIC0190E
Page 2594 of 3061

RSU-4
< SERVICE INFORMATION >
NOISE, VIBRATION AND HARSHNESS (NVH) TROUBLESHOOTING
NOISE, VIBRATION AND HARSHNESS (NVH) TROUBLESHOOTING
NVH Troubleshooting ChartINFOID:0000000003532655
Use chart below to help you find the cause of the symptom. If necessary, repair or replace these parts.
×: ApplicableReference page
RSU-21RSU-30
—
—
—
RSU-21
RSU-23RSU-37
PR-3, "
NVH Troubleshooting Chart
"
RFD-7, "
NVH Troubleshooting Chart
"
FAX-4, "
NVH Troubleshooting Chart
"
FSU-4, "
NVH Troubleshooting Chart
"
WT-4, "
NVH Troubleshooting Chart
"
WT-4, "
NVH Troubleshooting Chart
"
FAX-4, "
NVH Troubleshooting Chart
"
BR-4, "
NVH Troubleshooting Chart
"
PS-5, "
NVH Troubleshooting Chart
"
Possible cause and SUSPECTED PARTS
Improper installation, looseness
Shock absorber deformation, damage or deflection
Bushing or mounting deterioration
Parts interference
Spring fatigue
Suspension looseness
Incorrect wheel alignment
Stabilizer bar fatigue
PROPELLER SHAFT
DIFFERENTIAL
FRONT AXLE
FRONT SUSPENSION
TIRES
ROAD WHEEL
DRIVE SHAFT
BRAKES
STEERING
SymptomNoise×××××× ××× ××××××
Shake×××× × × × ××××××
Vibration××××× × × ×× × ×
Shimmy×××× × × ××× ××
Shudder ××× × ××× ××
Poor quality ride or handling××××× ×× × ×××
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CAN COMMUNICATION
RSU-5
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CAN COMMUNICATION
System DescriptionINFOID:0000000003532656
Refer to EC-32 .
Page 2596 of 3061

RSU-6
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
TROUBLE DIAGNOSIS
How to Perform Trouble Diagnosis for Quick and Accurate RepairINFOID:0000000003532657
INTRODUCTION
The rear load leveling air suspension system uses an electronic con-
trol unit to control major functions. The control unit accepts input sig-
nals from the height sensor and controls compressor and exhaust
valve operation.
It is much more difficult to diagnose a rear load leveling air suspen-
sion system problem that occurs intermittently rather than continu-
ously. Most intermittent problems are caused by poor electrical
connections or faulty wiring. In this case, careful checking of suspi-
cious circuits may help prevent the replacement of good parts.
Before undertaking actual checks, take just a few minutes to talk with
a customer who approaches with an air suspension system com-
plaint. The customer is a very good source of information on such
problems, especially intermittent ones. Through discussion with the
customer, find out what symptoms are present and under what con-
ditions they occur.
Start your diagnosis by looking for basic mechanical problems first.
This is one of the best ways to troubleshoot concerns on an air sus-
pension system equipped vehicle. Also check related Service Bulle-
tins for information.
CLARIFY CONCERN
• A customer's description of a vehicle concern may vary depending
on the individual. It is important to clarify the customer's concern.
• Ask the customer about what symptoms are present under what
conditions. Use this information to reproduce the symptom.
SEF233G
SEF234G
SBR339B
Page 2597 of 3061
TROUBLE DIAGNOSIS
RSU-7
< SERVICE INFORMATION >
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WORK FLOW
WEIA0077E
Page 2598 of 3061
RSU-8
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Component Parts and Harness Connector Location
INFOID:0000000003532658
WEIA0140E
Page 2599 of 3061
TROUBLE DIAGNOSIS
RSU-9
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Wiring Diagram - A/SUSP -INFOID:0000000003532659
WEWA0049E
Page 2600 of 3061
RSU-10
< SERVICE INFORMATION >
TROUBLE DIAGNOSIS
Basic Inspection
INFOID:0000000003532660
AIR HOSES
1. Check for pinched or damaged air hoses between the suspension air reservoir and each load leveling rear
air suspension shock absorber. Reposition, repair or replace hoses as necessary.
2. Check the air hose connections at the suspension air reservoir and at the shock absorbers for leaks. If
connections are leaking, repair or replace hoses as necessary.
WEWA0070E