John Deere 670C, 670CH, 672CH, 770C, 770CH, 772CH Motor Grader Pdf Diagnostic, Operation and Tests Service Manual TM1606

John Deere 670C, 670CH, 672CH, 770C, 770CH & 772CH Motor Grader Diagnostic & Operation Test Manual TM1606

A motor grader can still move and perform basic work while hiding a serious fault in its transmission, hydraulic system, engine controls or hydraulic front-wheel drive. That is where John Deere TM1606 becomes useful. This is not simply a maintenance reference—it is a Diagnostic, Operation and Test Technical Manual built around finding the cause of a machine symptom through operational checks, electrical diagnostics, pressure measurements, hydraulic tests and system-specific troubleshooting.

The publication covers the 670C, 670CH, 672CH, 770C, 770CH and 772CH motor graders. The manual is particularly valuable on the CH and 672CH/772CH hydraulic front-wheel-drive configurations, where HFWD pumps, wheel motors, charge pressure and electronic controls add another layer to the diagnostic process.

Machine Specification Table

Model	Engine	Maximum Published Net Power	Peak Net Torque	Typical / Standard Operating Weight	Maximum Blade Pull
670C	John Deere PowerTech 6068H, 6.785 L	140 hp / 104 kW	496 lb-ft / 673 Nm	30,000 lb / 13,608 kg standard	24,248 lb / 10,997 kg
670CH	John Deere PowerTech 6068H, 6.785 L	Up to 185 hp / 138 kW	625 lb-ft / 847 Nm	30,200 lb / 13,699 kg standard	24,428 lb / 11,078 kg
672CH	John Deere PowerTech 6068H, 6.785 L	Up to 185 hp / 138 kW	625 lb-ft / 847 Nm	31,820 lb / 14,434 kg standard	39,310 lb / 17,827 kg
770C	John Deere PowerTech 6081H, 8.1 L	155 hp / 116 kW	Model/configuration dependent	31,300 lb / 14,195 kg standard	27,810 lb / 12,612 kg
770CH	John Deere PowerTech 6081H, 8.1 L	Up to 185 hp / 138 kW	Model/configuration dependent	31,500 lb / 14,286 kg standard	27,990 lb / 12,694 kg
772CH	John Deere PowerTech 6081H, 8.1 L	Up to 185 hp / 138 kW	Model/configuration dependent	33,120 lb / 15,020 kg standard	43,860 lb / 19,891 kg

John Deere's published C-Series II specifications vary power by gear and configuration on CH models. Operating weight and blade-pull figures also depend on equipment and test conditions. The figures above are provided for machine identification and comparison, not as replacement specifications for an individual machine.

The Diagnostic Difference Between the C, CH and 6WD/HFWD Machines

The model names in this publication represent several different machine configurations. The 670C and 770C use the base engine configurations, while the CH models provide higher power characteristics. The 672CH and 772CH add hydraulic front-wheel drive, giving the technician additional hydraulic and electronic systems to test.

John Deere's specifications identify the HFWD system as a dual-path arrangement using separate left- and right-side variable-displacement axial-piston pumps and wheel motors. The system includes selectable aggressiveness control and inching capability. TM1606 therefore contains dedicated HFWD theory, diagnostic information, adjustments and tests rather than treating front-wheel drive as a conventional mechanical axle problem.

What TM1606 Is Designed to Diagnose

System	Diagnostic Focus
Engine	Starting problems, low power, fuel system, turbocharger boost, intake leakage, cooling airflow and engine diagnostic information
Electrical System	Wiring diagrams, component locations, subsystem diagnostics, ECU circuits, CAN information and diagnostic trouble codes
HFWD	Front-wheel-drive theory, controller operation, charge pressure, pumps, wheel motors and system tests
Power Train	Transmission operation, diagnostic codes, clutch/solenoid circuits, shift functions, sensors and drivetrain testing
Hydraulic System	Main hydraulic pump, pressure, flow, valve functions, steering, blade functions and hydraulic circuit diagnosis
Heating & A/C	System operation, refrigerant-related checks, electrical controls and performance testing

HFWD Diagnostics for 672CH and 772CH

The 672CH and 772CH deserve special attention because their hydraulic front-wheel-drive system can produce symptoms that look like engine, transmission or tire problems. A grader that loses front-wheel assistance, develops abnormal HFWD temperature, shows charge-pressure warnings or responds differently at low speed requires a different diagnostic approach from a standard 670C or 770C.

TM1606 contains dedicated HFWD information covering:

• Hydraulic front-wheel-drive theory of operation
• HFWD controller circuit operation
• HFWD controller circuit schematics
• Separate left and right hydraulic drive circuits
• HFWD charge-pressure information
• HFWD pump and wheel-motor diagnostics
• HFWD adjustments and checks
• HFWD operational tests
• 15-position aggressiveness-control operation
• Inching operation down to zero machine speed

John Deere specifies the HFWD system for the 672CH and 772CH as using two axial-piston pumps and separate left/right systems. This makes the diagnostic procedures especially relevant when one side behaves differently from the other or when front-wheel assistance changes with operating conditions.

Transmission Diagnostics Are More Than Fault-Code Reading

TM1606 contains detailed transmission diagnostic information, including specific F-series transmission diagnostic trouble codes. The manual addresses conditions involving gear solenoids, speed pickups, gear-position switches, forward/reverse circuits and transmission-control functions.

For example, some transmission solenoid faults can place the grader into a limited solenoid limp-home mode. That can make the machine appear to have a shifting problem that changes depending on the selected gear. TM1606 explains the diagnostic behavior so the technician can test the circuit responsible instead of assuming that the complete transmission has failed.

The publication also covers transmission diagnostic conditions associated with the input and output speed pickups, gear-position switch module, forward/reverse switch module and transmission control unit.

Engine Diagnostics for the 6068H and 6081H

The 670C/670CH/672CH machines use the John Deere PowerTech 6068H family, while the 770C/770CH/772CH use the PowerTech 6081H. TM1606 separates applicable engine tests according to these configurations and also identifies serial-number-specific procedures.

Engine Diagnostic Area	Examples of Information Included
Starting	Cranks-but-won't-start and hard-start diagnostic procedures
Power	Engine does not develop full power diagnostic procedure
Fuel System	Fuel-line leakage, fuel pressure and supply-pump testing
Air Intake	Air-filter restriction and intake-system leakage tests
Turbocharger	Intake-manifold pressure / turbo boost and wastegate testing
Cooling	Radiator airflow testing
Electronic Control	Engine controller circuits, subsystem diagnostics and diagnostic codes on applicable configurations

This is useful for a grader that cranks slowly, starts hard, smokes, loses power under load or fails to reach expected operating performance. The test procedures help distinguish fuel delivery, intake restriction, turbocharger, cooling airflow and electronic-control problems.

Electrical & Wiring Diagnosis

Older electronically controlled motor graders can be difficult to diagnose when a technician has only a multimeter and a symptom. TM1606 provides the system-level information needed to understand how the circuits are supposed to work.

• Electrical circuit malfunction diagnosis
• System functional schematics
• Wiring diagrams
• Connector end-view information
• Component location diagrams
• Open-circuit diagnosis
• Grounded-circuit diagnosis
• High-resistance circuit diagnosis
• CAN theory of operation
• Engine controller circuit information
• Display monitor circuit information
• HFWD controller circuits
• Engine intake-air heater circuits
• Diagnostic trouble codes and reference tests

The manual also addresses changes associated with serial-number breaks, including HFWD controller schematics before and after S.N. 575171. That level of detail is important when a wiring diagram for one production range does not match the harness installed on another machine.

Hydraulic Testing for Blade and Steering Problems

The hydraulic system is at the center of grader productivity. A problem with blade lift, circle movement, steering or auxiliary equipment can originate in the pump, control valve, circuit pressure, leakage or an individual actuator.

TM1606 provides hydraulic theory, malfunction diagnosis, adjustments and tests so the technician can work from measured hydraulic behavior rather than guessing which component should be replaced.

Possible Complaint	Relevant Diagnostic Direction
Blade moves slowly	Hydraulic pump performance, system pressure and circuit checks
Blade function is weak under load	Hydraulic pressure and valve/circuit diagnosis
Steering response is abnormal	Steering hydraulic circuit and component testing
Circle function is inconsistent	Grading-device hydraulic and control-system diagnosis
Hydraulic function drifts	Leakage and actuator/circuit diagnosis
Multiple hydraulic functions are slow	Main pump and system-level hydraulic testing

Machine Performance Data Relevant to Testing

Specification	670C / 670CH / 672CH	770C / 770CH / 772CH
Engine displacement	6.785 L	8.1 L
Engine family	PowerTech 6068H	PowerTech 6081H
Transmission	PowerShift Plus, 8 forward / 8 reverse	PowerShift Plus, 8 forward / 8 reverse
Maximum listed travel speed	25.0 mph / 40.2 km/h	25.8 mph / 41.5 km/h
Main hydraulic pump	45.6 gpm / 173 L/min standard; larger pump optional	45.6 gpm / 173 L/min standard; larger pump available
Hydraulic standby pressure	Approx. 2,550 psi	Configuration dependent
Blade	12 ft × 24 in standard published configuration	12 ft × 24 in standard published configuration
Circle rotation	360°	360°
Front axle oscillation	32° total	32° total
Wheel lean	20° each direction	20° each direction

Operational Checkout Before Component Replacement

TM1606 includes a complete Operational Checkout Procedure. This is important because a machine complaint should ideally be reproduced and narrowed down before a technician removes a pump, valve, transmission component or electrical module.

The checkout process provides a practical starting point for checking machine behavior and then directing the technician into the appropriate engine, electrical, HFWD, powertrain or hydraulic diagnostic group. That structure makes the publication useful for field technicians who need to diagnose a grader at the jobsite before moving it into a workshop.

Diagnostic Trouble Codes and Electronic Controls

The electronic systems on these graders are covered at a level that goes beyond a simple list of codes. TM1606 provides diagnostic information for applicable engine and transmission controllers, display-monitor circuits, HFWD controller circuits and other electronic subsystems.

Transmission codes such as the F301–F308 solenoid-related codes and speed-pickup codes in the F375–F399 range illustrate why this manual is useful for troubleshooting. A code can identify a circuit or sensor condition, but the diagnostic procedure is what helps determine whether the actual cause is wiring, connector damage, a sensor, the controller or another component.

Heating and Air Conditioning Diagnostics

The manual also includes a dedicated Heating and Air Conditioning section covering system theory, operational checks, diagnostic information, adjustments and tests. This is useful when a grader's HVAC problem is not simply a lack of refrigerant but involves controls, system pressure, electrical operation or component performance.

Manual Specification Table

Manual Detail	Information
Publication Number	TM1606
Document Type	Diagnostic, Operation and Test Technical Manual
Models	670C, 670CH, 672CH, 770C, 770CH, 772CH
Machine Type	John Deere C-Series Motor Grader
Language	English
Format	PDF
Identified Edition	22SEP04 English edition
Core Sections	General Information, Operational Checkout, Engine, Electrical System, HFWD, Power Train, Hydraulic System, Heating & Air Conditioning
Electrical Diagrams	Included
Diagnostic Trouble Codes	Included for applicable electronic systems
Searchable Digital Edition	Yes, for compatible PDF reproductions
Printable	Yes
Reported Page Count	Digital reproductions vary; approximately 1,022–1,314 pages have been reported
Reported PDF Size	Approximately 36.43 MB for one identified digital reproduction

Page count and file size can differ between scans, digital reproductions and compressed editions. The publication number and edition date are the more reliable identifiers for matching TM1606.

Useful Diagnostic Scenarios

Machine Symptom	TM1606 Areas to Check
670C starts but lacks power	6068H engine diagnostics, intake restriction, fuel system, turbo boost and radiator airflow
670CH transmission remains in limited operation	Transmission DTCs, solenoid circuits, shift controls and limp-home diagnostics
672CH loses front-wheel assistance	HFWD controller, charge circuit, dual hydraulic pumps and wheel-motor system
770C has a hard-start or low-power complaint	6081H engine diagnostics, fuel pressure, intake system and turbocharger tests
772CH shows HFWD warning information	HFWD controller, charge pressure, temperature and front-drive circuit tests
Grader blade functions are slow	Main hydraulic system pressure, flow and control-circuit testing
Transmission gear indication is incorrect	Gear-position switch, forward/reverse circuit and transmission-control diagnostics
Electrical fault appears intermittent	Open-circuit, grounded-circuit, high-resistance and connector testing

Technical PDF Features

• English-language John Deere diagnostic and test information
• PDF format for workshop and field reference
• Searchable content in compatible digital editions
• Printable technical pages
• Electrical system diagrams and component-location information
• Diagnostic trouble-code information
• Operational checkout procedures
• Hydraulic and HFWD test procedures
• Engine performance and fuel-system tests
• Powertrain and transmission diagnostics
• Heating and air-conditioning test information

Frequently Asked Questions

What models are covered by John Deere TM1606?

TM1606 covers the 670C, 670CH, 672CH, 770C, 770CH and 772CH motor graders.

What type of manual is TM1606?

TM1606 is a Diagnostic, Operation and Test Technical Manual. It is designed to diagnose machine systems through operational checks, theory of operation, adjustments, measurements and tests.

Does TM1606 include electrical wiring diagrams?

Yes. The electrical section includes system diagrams, wiring information, component-location information, subsystem diagnostics and applicable diagnostic trouble codes.

Does the manual cover HFWD?

Yes. TM1606 includes a dedicated Hydraulic Front Wheel Drive section. HFWD is particularly relevant to the 672CH and 772CH configurations.

What engine is used in the 670C and 670CH?

The C-Series II specifications identify the John Deere PowerTech 6068H six-cylinder engine with 6.785 L displacement for the 670C, 670CH and 672CH.

What engine is used in the 770C and 770CH?

The 770C, 770CH and 772CH use the John Deere PowerTech 6081H six-cylinder engine family with approximately 8.1 L displacement.

Can TM1606 diagnose transmission faults?

Yes. The powertrain section includes transmission theory, diagnostic information, adjustments and tests, while the electrical section contains relevant transmission-control circuits and diagnostic codes.

Does it include hydraulic tests?

Yes. The hydraulic system section includes theory of operation, malfunction diagnosis, adjustments and testing for the grader's hydraulic functions.

Does TM1606 cover engine starting and low-power problems?

Yes. The engine diagnostic section includes procedures for hard starting, crank-but-won't-start conditions, insufficient engine power, fuel-system faults, intake leakage, turbocharger boost and radiator airflow.

How important is the machine configuration when using this manual?

It is very important. TM1606 contains serial-number-specific procedures for some engine, electrical and HFWD systems. Always identify the complete machine model and serial number before selecting a test procedure.

A Diagnostic Manual Built Around Measurements

John Deere TM1606 is most valuable when the machine has a symptom but the failed component is not yet obvious. Instead of jumping directly to a transmission, pump, controller or hydraulic motor replacement, the technician can begin with the operational checkout and move into the relevant test group.

For the 670C and 670CH, that can mean narrowing an engine or PowerShift problem. For the 672CH and 772CH, it can mean tracing an HFWD issue through the controller, charge circuit, pumps and wheel motors. For the 770C and 770CH, the engine and powertrain sections provide the corresponding diagnostic path for the larger 6081H-powered grader.

When matched to the correct machine configuration and serial-number range, TM1606 provides the detailed diagnostic procedures, electrical diagrams, DTC information, hydraulic tests, HFWD checks, engine tests and powertrain troubleshooting needed to turn a machine symptom into a measurable service diagnosis.