John Deere 3120, 3320, 3520 and 3720 Tractors Diagnostic and Repair Technical Manual (TM2138)

John Deere 3120 3320 3520 3720 Compact Utility Tractors Diagnostic and Repair Technical Manual (TM2138 20JUN13)

This factory technical manual provides structured diagnostics, detailed repair procedures, and system operation theory for John Deere 3120, 3320, 3520, and 3720 compact utility tractors. It supports accurate fault isolation, correct adjustments, and workshop-grade service across engine, electrical, power train, hydraulics, steering, PTO, and brakes.

Model Covers:

John Deere 3120
John Deere 3320
John Deere 3520
John Deere 3720

File Format: PDF

Size: 97.17 MB

No. of pages: 1849

Language: English

Delivery Method: Instant Download - Access your file immediately after purchase.

📑 Included Sections:

Safety and Specifications

• Safety practices for fluids, pressurized lines, lifting and blocking
• Torque charts for metric and unified fasteners, sealant and O-ring guidelines
• Fuel and lubricants, coolant, and serial number identification points

Engine

• Fuel, cooling, air intake, turbocharger and lubrication system operation
• Compression, valve clearance, belt and throttle adjustments
• Cooling pressure, thermostat, oil pressure and crankcase tests
• Component service for filters, injection pump and nozzles, turbo and manifolds

Electrical - North America

• Main schematics for PRT, eHydro and Auto HST with harness legends
• Power, cranking, manifold heater, charging and lighting circuit operation
• PTO, MFWD, display panel, cruise control and mode switch diagnostics
• Test procedures for sensors, switches, relays, alternator and starter

Electrical - EEC

• Regional schematics for Pre MY08, MY08 and MY13 configurations
• Load center layouts, harness color codes and component locations
• Power, cranking, heater, fuel shutoff and instrument circuits with diagnosis
• Display panel fault codes and troubleshooting charts

Diagnostics and Calibrations

• Display panel fault code charts for eHydro and Auto HST
• Electronic Drive Controller configuration and calibration routines
• Service ADVISOR connection, code retrieval and control system calibration

Power Train - PowrReverser (PRT)

• Control valve and clutch operation theory with pressure test procedures
• Linkage adjustment, hydraulic pressure tests and troubleshooting
• Traction clutch service, machine splitting and gear set removal

Power Train - Hydrostatic

• Hydrostatic transmission operation and range power flow
• High pressure relief and charge pump pressure tests
• Pedal sensors, controller checks and transmission disassembly

Power Train - Final Drive and PTO

• Differential, rear axle, MFWD front axle and spindle service
• Backlash and pinion depth adjustment with inspection procedures
• PTO clutch and brake theory with rear and mid PTO repair steps

Hydraulics

• Steering, SCV, rockshaft and diverter valve schematics
• System pressure and flow testing, charge pressure and PTO clutch tests
• Rockshaft lift cycle, leakage checks and position feedback adjustment

Steering and Brakes

• Steering system checks, pressure tests and toe-in adjustment
• Brake operation diagnostics with pedal and parking adjustments
• Component removal, inspection and assembly procedures

Miscellaneous Service

• ROPS, operator platform, panels, seat and fender service
• Battery and fuel tank removal and installation

For complete service information, also see:
Machine Connection Information .......... CTM441

This John Deere 3120 3320 3520 3720 Diagnostic and Repair Manual delivers controller logic, calibrated tests and precise mechanical procedures to restore performance and ensure dependable operation.