![John Deere Model R Diesel Repair Manual [Tractor]](https://youfixthis.com/wp-content/uploads/2012/02/Manual_Download-300x300.jpg)
Part of the John Deere Repair Manuals.
This is the John Deere factory diagnostics manual (TM4726) for the 6020, 6120, 6220, 6320, 6420, 6420S, 6520, 6620, 6820, 6920 and 6920S tractors. Across 1,496 pages it covers every electronic control unit, all diagnostic trouble codes, observable symptom trees and step-by-step system diagnostics for the engine, electrical system, all four transmission types (SyncroPlus, Power Reverser, AutoPowr/IVT and PowrQuad), drive systems, steering, hydraulics and the operator cab. It is the same reference John Deere dealer technicians use alongside Service Advisor, giving you the voltage specs, resistance values and symptom trees to trace a fault to its root cause.
What's Inside This Manual
| System | Pages | Key Topics |
|---|---|---|
| General Information | Safety Precautions, Diagnostic Tool Usage, Dtc Reading and Clearing Procedures, System Component Locations, Electrical Measurement Basics | |
| Diagnostic Trouble Codes | Atc, Bcu, Bif, ECU, Epc, Jdl, Plc, Prf, Sfa, Sic, Ssu, Tcu, Tec, Uic Controller Fault Codes with Descriptions and Corrective Actions | |
| Observable Symptoms | Engine Symptoms, Transmission Shift Symptoms, Hydraulic Symptoms, Electrical and Instrument Panel Symptoms, PTO Engagement Symptoms | |
| Engine | No-Start Diagnosis, Fuel Delivery Testing, Cooling System Faults, Oil Pressure Fault Codes, Injector Pump Diagnostics | |
| Electrical System | System Voltage Tests (11.2-15.4 V Range), Battery Diagnostics, Alternator Tests, Wiring Harness Inspection, Solenoid Valve Resistance and Current Checks | |
| Electronics | CAN Bus Communication Diagnostics, Controller Area Network Faults, Sensor Diagnostics, Isobus and JDLink Interface | |
| SyncroPlus Transmission | Gear Engagement Faults, Clutch Diagnostics, Shift Quality Symptoms, SyncroPlus Dtc Interpretation | |
| Power Reverser Transmission | Reverser Clutch Diagnostics, forward/reverse Engagement Faults, Prc Fault Code Procedures | |
| AutoPowr/IVT Transmission | Infinitely Variable Transmission Diagnostics, Hydrostatic Unit Faults, IVT Warning Light Procedures, 6420S/6520/6820/6920S Specific | |
| PowrQuad, PowrQuad Plus and AutoQuad Transmissions | Power Shift Clutch Faults, AutoQuad Shift Diagnostics, PowrQuad Plus Dtc Procedures | |
| Drive Systems | Front Axle 4WD Engagement Diagnostics, Differential Lock Solenoid Tests (10-12 Ohm, 1-1.2 a), Front Axle Clutch Faults | |
| Steering and Brakes | Hydraulic Steering Diagnostics, Brake Pressure Sensor Tests, Steering Fault Code Procedures | |
| Hydraulic System | Hydraulic Pump Diagnostics, Valve Block Fault Isolation, Pressure Testing, Remote Cylinder Diagnostics, Load-Sensing Circuit Tests | |
| Operator's Cab | Instrument Panel Diagnostics, CommandCenter Monitor Faults, Air Conditioning System Diagnostics, Sfa and Sic Control Diagnostics |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| System Voltage (Ignition ON, engine OFF) | 11.2 - 12.7 volts | |
| System Voltage (Engine running, low idle) | 11.2 - 15.4 volts | |
| System Voltage (Engine at 1500 rpm) | 12.5 - 15.4 volts | |
| Rear PTO Solenoid Supply Voltage (disengaged) | 0 volts | |
| Rear PTO Solenoid Supply Voltage (engaged) | 12 volts | |
| Differential Lock Solenoid Valve Resistance | 10 - 12 ohms at 20 degrees C | |
| Differential Lock Solenoid Voltage (disengaged) | 0 volt | |
| Differential Lock Solenoid Voltage (engaged) | 12 volts | |
| Differential Lock Solenoid Amperage (engaged) | 1 - 1.2 amps at 20 degrees C and 12-volt nominal | |
| Front PTO Solenoid Supply Voltage (disengaged) | 0 volts | |
| Front PTO Solenoid Supply Voltage (engaged) | 12 volts |
