Only the factory book settles the pressure settings and analyzer parameters on a JLG 450A or 450AJ aerial work platform, and this 472-page JLG 450A, 450AJ service manual PDF (publication 3121180) is that book. Wiring diagrams and hydraulic schematics close out the volume, tracing each circuit to its Deutsch connector and each oil line from the variable pump to the cylinders. Trouble code definitions for Ford EFI, GM dual fuel and Deutz EMR 2 engines fill a long chapter, and the control system section shows you how to connect the hand held analyzer and run the system test. Set main relief at 3300 psi (227.5 bar), and torque wheel nuts in three stages: 40, 100, then 170 ft-lb (255 Nm). Intermittent faults on a dual fuel engine eat whole shifts. Bookmarks and a searchable text layer take you straight to the fix, and your lift back to raising crews safely.
What's Inside This JLG 450A, 450AJ Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction - Maintenance Safety Precautions | 3-16 | Hydraulic System Safety, Maintenance |
| Specifications | 17-36 | Capacities, Tires, Engine, Specifications and Performance Data, Function Speeds, Torque Requirements, Lubrication, Major Component Weights |
| General | 37-50 | Machine Preparation, Inspection, And Maintenance, Service and Guidelines, Lubrication and Information |
| Tires, Wheels, and Torque Hubs | 51-80 | Tire Inflation, Tire Damage, Torque Hub Disassembly, Torque Hub Assembly, Roll and Leak Testing |
| Drive Motor and Oscillating Axle | 81-108 | Drive Motor Disassembly, Drive Motor Inspection, Drive Motor Assembly, Oscillating Axle Bleeding, Lockout Test |
| Swing Bearing and Swing Motor | 109-145 | Swing Bearing Removal, Swing Bearing Installation, Swing Motor Disassembly, Swing Motor Inspection, Swing Motor Assembly |
| Engine Maintenance and Diagnostics | 146-181 | Ford EFI Engine Diagnostics, Deutz Engine Maintenance, GM Engine Dual Fuel System, Perkins Engine Maintenance, Engine Radiator Fill Procedure |
| Diagnostic Trouble Codes (DTCs) | 182-266 | LPG Fuel System Diagnosis, DTC Definitions, CAN J1939 Communication Faults, Microprocessor Failure Codes, Throttle Position Sensor Diagnostics |
| Boom & Platform | 267-290 | Boom Maintenance, Rotator, Rotary Actuator |
| Hydraulics | 291-336 | Cylinder Repair, Hydraulic Pump, Variable Pump, Hydraulic Component Start-Up Procedures and Recommendations, Pressure Setting Procedure |
| JLG Control System | 337-416 | Introduction, Connect JLG Control System Analyzer, Using Analyzer, Changing Hand Held Analyzer Access Level, Parameters Using the Hand Held Analyzer, Machine Setup |
| Basic Electrical Information & Schematics | 417-472 | Multimeter Basics, Applying Silicone Dielectric Compound to Electrical Connections, AMP Connector, Deutsch Connectors |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| Wheel Torque Chart | 1st Stage 40 ft-lb (55 Nm), 2nd Stage 100 ft-lb (130 Nm), 3rd Stage 170 ft-lb (255 Nm) | p. 52 |
| Auxiliary Pump Torque A | 96 to 120 inch-pounds (11 to 13.5 Nm) | p. 143 |
| Auxiliary Pump Torque B | 84 inch-pounds (9.5 Nm) | p. 143 |
| Drive belt tension | 1/2 inch (13mm) | p. 170 |
| Bang-Bang Main Relief pressure | 3300 psi (227.5 Bar) | p. 332 |
| Steer relief pressure | 2500 psi (172 Bar) | p. 332 |
| Contact wire pull force | 1 or 2 lbs. | p. 420 |
| Screwdriver blade width for wedge lock disassembly | 3/16 inch (4.8 mm) | p. 422 |
| Fuel Tank Capacity | 17 gallons (64.3 liters) | p. 17 |
| Drive Hub Oil Capacity | 23.75 oz. (0.7 liters) | p. 17 |
| Drive Brake Oil Capacity | 2.7 oz. (0.08 liters) | p. 17 |
| Wheel Lug Torque | 170 ft. lb. (230 Nm) | p. 19 |
JLG 450A, 450AJ Common Problems This Manual Covers
JLG 450A/450AJ drive motor turns fine unloaded but slows down under load or will not turn
Check the drive motor for excessive case drain flow before pulling it. Remove and inspect the motor following the drive motor procedures beginning on page 81. On reassembly, torque the drive motor to axle fasteners to 120 ft. lb. (163 Nm), then verify the motor no longer free wheels.
Manual Section: Drive Motor and Oscillating Axle p. 81Swing motor leaking oil and losing significant speed under load when swinging the boom
Inspect the swing motor for external oil leakage and test for undue high pressure before condemning it. Verify swing relief pressure against 1700 psi using the pressure setting procedure on page 332. If speed still drops under load, remove and inspect the motor following the swing motor section starting on page 109.
Manual Section: Swing Bearing and Swing Motor p. 109Platform footswitch problem help fault code with drive, steer, and boom functions locked out
Connect the JLG Control System Analyzer following page 337 and read the help fault code before touching any wiring. Test the footswitch and operator inputs through the system test menu, then check the 15 amp platform box circuit breaker on page 438. Never bypass the footswitch; it protects the operator in the basket.
Manual Section: JLG Control System p. 337Tilt detection or load sensing system fault code with platform functions cut out
Verify the serial number first; tilt detection and load sensing faults appear in the help fault codes for S/N 0300066949 and S/N 1300000001 to present. Read the code with the analyzer following page 337, then check machine diagnostics parameters. Clear it only after finding the cause; these systems protect the operator in the basket.
Manual Section: JLG Control System p. 337Basket leveling system fault code set on platform level up or level down
Check the basket leveling fault code with the analyzer following page 337 before adjusting any hydraulics. Measure platform level up pressure against 2800 psi (193 Bar) and level down against 1800 psi (125 Bar) using the pressure setting procedure on page 332. Run the test with nobody in the basket.
Manual Section: JLG Control System p. 337Engine on LPG hard starts or will not start, with fuel system pressure problems
Check for stored DTCs first, then work through the LPG fuel system diagnosis in the DTC section starting on page 182 to test fuel system pressure. If the engine starts but cuts out, stumbles, or idles rough, continue into the symptom diagnosis charts before replacing any fuel components.
Manual Section: Diagnostic Trouble Codes (DTCs) p. 182Frequently Asked Questions
How do I clear diagnostic trouble codes on a JLG 450AJ?
To clear ECM trouble codes, disconnect the negative terminal from the battery for approximately 15 minutes. p. 146
How do I clear DTC 524 on a JLG 450AJ?
DTC 524 indicates low oil pressure. To reset it, you must first address the underlying cause, such as a faulty oil pressure switch or oiling system issue. Once the issue is resolved, the fault can be cleared using the JLG Control System Analyzer by navigating to the Faults page and selecting the clear function. p. 230
What is the torque specification for the wheel lugs on a JLG 450A/AJ?
The wheel lugs must be torqued in three stages to reach the final specification of 170 ft-lb (230 Nm). p. 52
What is the hydraulic oil capacity for the JLG 450A/AJ?
For machines with serial number 0300070586 and later, the hydraulic tank capacity is 27 gallons (102 liters), with 23.6 gallons (89 liters) to the full line on the sight gauge. p. 17
What is the torque spec for the drive hub to axle bolts on a JLG 450A, 450AJ?
The drive hub to axle bolts must be torqued to 240 ft. lb. (325 Nm). p. 19
Do I get instant access to this JLG 450A Service Manual?
Immediate download of the complete 472-page searchable Service Manual. Access it on any device, from a laptop at your desk to a phone in the field.
Am I able to print pages from this JLG 450A manual?
Yes. Many mechanics print the section they need for their own shop and bring it to the bench.
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