Honda TRX680FA / TRX680FGA 2006 ATV Service Manual

This Honda service manual covers the TRX680FA and TRX680FGA. It was issued by Honda Motor Co., Ltd., Service Publication Office, in November 2005.

PDF Search, Navigation, and Page Count

Text search and diagram detail: An embedded OCR text layer supports searching, but recognition errors can prevent exact matches. Chapter bookmarks are included, with some inaccurate labels. Small labels in the main wiring diagram are partly difficult to read even when enlarged.

One printable PDF contains 565 pages, including two opening pages of manual-use instructions, contents, and symbols, followed by 563 pages across 26 numbered sections.

Engine, PGM-FI, and Automatic Drivetrain Service

These selected coverage highlights outline the main workshop content. Additional topics include body-panel and exhaust removal, plus air-cleaner servicing.

• Engine repair: Step-by-step procedures for engine removal, cylinder-head disassembly, valve-guide replacement, valve-seat refacing, cylinder and piston service, and crankcase separation.

• PGM-FI diagnosis: Fuel-pressure and pump-flow testing, DTC troubleshooting, injector and throttle-body service, sensor checks, and Idle Air Control Valve inspection.

• Automatic transmission and 4WD: Shift-valve-body service, torque-converter inspection, shift-clutch/mainshaft disassembly and assembly, ESP operation, and selectable-4WD fault diagnosis.

• Lubrication and cooling: Oil-pump inspection and pressure testing, oil-cooler service, cooling-system leak testing, thermostat inspection, and water-pump repair.

• Suspension and final drives: Steering, tie rods, wheel hubs, knuckles, drive shafts, front differential service, and rear final-drive gear-contact and backlash inspection.

• Brake service: DOT 4 brake-fluid replacement, hydraulic bleeding, pad and disc inspection, master-cylinder repair, caliper overhaul, and parking-brake adjustment.

• Electrical troubleshooting: Charging-system tests, ignition peak-voltage checks, electric-starter repair, wiring diagrams, connector locations, and cable/harness routing.

The manual is written for readers who already have basic maintenance knowledge of Honda ATVs, motorcycles, or motor scooters.

Engine Teardown and Maintenance References

Cylinder-head, rocker-arm, valve, camshaft, cylinder, and piston work can be performed with the engine installed. Crankshaft and balancer service requires engine removal and crankcase separation.

Mechanical inspection sections provide component dimensions, clearances, and wear limits. Maintenance references cover factory intervals, oil quantities for draining, filter changes and disassembly, tire pressures, toe settings, brake wear, and critical fastener torques.

PCM Diagnosis and Shared Sensor Faults

The PCM integrates engine, transmission, and selectable-4WD control. The diagnostic sections help distinguish shared sensor or wiring faults from mechanical problems before components are replaced.

PGM-FI troubleshooting covers MAP, ECT, TP, IAT, injector, IACV, rear vehicle-speed sensor, and PCM/EEPROM faults. Drivetrain diagnosis addresses the front final clutch, A/T clutch-pressure-control solenoid, shift solenoids, gear-position inputs, and shared sensor faults.

Diagnostic access: HDS procedures cover DTC, freeze-data and current-data readout, plus PCM reset functions. MIL and drivetrain-indicator blink-code diagnosis is also provided; indicator blinking identifies main codes rather than the full subcodes available through HDS.

Certain A/T faults disable automatic shifting and anti-creep operation and hold the transmission in second gear. Selectable-4WD faults can default the machine to 2WD. These fail-safe descriptions explain operating symptoms that might otherwise be mistaken for separate faults.

Transmission Repair Scope and Workshop Tools

The torque converter and first shift clutch can be serviced with the engine installed. Mainshaft and second/third shift-clutch work requires engine removal and crankcase separation. These distinctions help you plan disassembly and workshop setup before starting repair work.

A faulty torque converter is replaced as an assembly rather than rebuilt internally. The transmission uses hydraulically operated wet multi-plate clutches, with engine oil serving as the hydraulic fluid. Related references include clutch clearances and wear limits, torque-converter lock-nut specifications, differential slip-torque checks, and final-drive backlash limits.

Factory tool references include pressure gauge set 07406-0020005 and fuel pressure gauge 07406-0040004. Electrical diagnosis references the HDS pocket tester TDS 3557-0112-01, SCS connector 070PZ-ZY30100, and test probe 07ZAJ-RDJA110. Differential inspection uses tool 07KMK-HC50101.

System Diagrams and Variant-Specific Electrical Work

Illustrations include the Lubrication System Diagram, PGM-FI System Diagram, Fuel Flow Chart, Shift Clutch Hydraulic Circuit and Operation, Automatic Transmission Performance Curve, and TRX680FA/FGA Wiring Diagram.

Connector-location and harness-routing pages identify PCM connections, shift-solenoid wiring, front and rear vehicle-speed sensors, front final-clutch wiring, and injector, IACV, MAP/TP, and ECT circuits.

Charging diagnosis includes current-leakage and alternator checks. Ignition coverage includes CKP-sensor testing, while the starting section covers relay diagnosis and starter-motor disassembly and inspection. Variant-specific material addresses GPS receiver communication and slow-start troubleshooting on the GPS model, plus Australia-only horn circuitry.

Throttle-Body, Cooling, and Electrical Precautions

The throttle body is factory preset; disturbing its white-painted fasteners can cause malfunction. The cooling section explains how silicate-containing coolant can prematurely wear water-pump seals or block radiator passages, while tap water can contribute to engine damage.

The electrical sections warn that disconnecting PCM connectors while current is flowing can cause damaging voltage surges.

Always review the safety messages and handling procedures in the Honda publication before beginning repair work, especially around pressurized fuel, hot coolant, brake hydraulics, electrical circuits, and heavy engine removal.

Selected Valve-Clearance and Pressure Specifications

The valve-clearance section specifies 0.15 mm (0.006 in) intake and 0.33 mm (0.013 in) exhaust, checked with the engine cold, below 35°C (95°F).

The PGM-FI fuel-pressure test specifies 284–304 kPa (41–44 psi) with the engine idling. Lubrication specifications give an oil pressure of 785 kPa (114 psi) at 5,000 rpm and an oil temperature of 80°C (176°F).