2006–2009 Honda TRX680FA, TRX680FGA Service Manual (P/N 61KRN10)

• Covers 2006–2009 Honda TRX680FA and TRX680FGA ATVs with the longitudinal single-cylinder engine, PGM-FI, dry-sump lubrication, selectable 2WD/4WD, and a torque-converter three-speed automatic transmission. This Honda Motor Co., Ltd. service publication is dated November 2005 and contains 567 PDF pages.
• PGM-FI and PCM coverage includes HDS/SCS diagnosis, MIL and DTC retrieval and clearing, freeze-data and current-data checks, connector testing, fuel-pressure diagnosis, and repair procedures for the sub-fuel-tank pump, throttle body, injector, ECT sensor, bank-angle sensor, PCM, and IACV.
• Automatic-transmission material runs from symptom-based fault isolation and hydraulic line/shift-clutch pressure testing through shift valve body and solenoid service, torque-converter inspection, shift-clutch/mainshaft repair, and separate D-N-R sub-transmission work.
• Engine repair chapters cover removal and installation, oil-pump and oil-cooler service, cooling-system testing, cylinder-head and valve work, valve-guide replacement and seat refacing, camshaft timing, cylinder/piston inspection, starter-clutch and alternator service, crankcase separation, crankshaft checks, and bearing replacement.
• Scheduled-maintenance coverage handles fuel and throttle checks, air-cleaner and spark-plug service, valve-clearance inspection, engine oil/filter and coolant service, drive-shaft boots, differential/final-drive lubricants, brakes, suspension, steering, spark arrester, and wheels/tires.
• Chassis sections document body and exhaust removal, front and rear suspension, wheel hubs and knuckles, steering-shaft and tie-rod service, wheel alignment, brake-fluid replacement and bleeding, master cylinders, calipers, pads, and discs.
• Front and rear drive-unit sections include drive-shaft and CV-joint service, differential/final-drive removal and disassembly, backlash and tooth-contact checks, shim selection, bearing and oil-seal replacement, and assembly and installation procedures.
• Diagram and reference support includes system schematics, connector and harness-routing views, exploded assembly illustrations, a full TRX680FA/FGA wiring diagram, component-specific torque tables, fluid data, wear limits, clearances, hydraulic test specifications, and electrical test values.

Coverage and Model-Specific Systems

The covered powerplant is the 674.9cc longitudinal single-cylinder engine. Identification pages locate the VIN, engine serial number, throttle-body identification number, color code, emissions label, and regional name or safety labels. Those references help confirm the exact machine and market configuration before parts or test procedures are selected.

TRX680FGA coverage goes beyond the model name. Separate combination-meter information and GPS receiver inspection are included, with troubleshooting for receiver communication faults and unusually long startup. The electrical material marks GPS-only circuits and also identifies the Australia-type horn circuit.

The PCM combines engine and transmission control functions, so the diagnostic chapters address PGM-FI, ignition, automatic-transmission, and selectable-4WD faults as related systems. AUTO and ESP operating modes, gear-position inputs, drive-mode and gearshift switches, shift solenoids, the clutch-pressure-control solenoid, and the front final clutch are all covered. When PGM-FI and automatic-transmission DTCs are stored together, the diagnostic logic directs the engine-management fault to be evaluated first.

Repair and Diagnostic Depth

Transmission coverage is substantially deeper than routine fluid service. Hydraulic line-pressure and individual shift-clutch pressure tests are paired with a troubleshooting chart that links abnormal readings to likely problems in the valve body, solenoids, clutches, feed pipes, torque converter, or oil pump. Internal repair coverage extends to the externally mounted shift valve body, shift solenoids, emergency valve, torque converter, mainshaft and hydraulic clutch assemblies, rear crankcase cover, selector linkage, and cable adjustment.

The PGM-FI section supports both scan-tool and manual fault retrieval. It documents HDS data functions, SCS connector use, MIL blink-code diagnosis, DTC clearing, fuel-supply testing, sensor and relay checks, PCM inspection, idle-speed diagnosis, and IACV service. Representative factory-tool callouts include SCS connector 070PZ-ZY30100, pressure-gauge set 07406-0020005, valve spring compressor 07757-0010000, and rear-drive pinion holder 07SMB-HM70200.

Engine work is carried through inspection and reassembly rather than stopping at removal. The top-end chapters cover compression checks, head and valve disassembly, valve-guide replacement, valve-seat inspection and refacing, camshaft and timing work, and final installation. Lower-engine material covers the cylinder and piston, connecting-rod small end, crankcase separation, crankshaft and balancer inspection, crankcase bearings, and case assembly. Separate lubrication and cooling chapters add oil-pressure testing, oil-pump overhaul, oil-cooler service, coolant replacement and bleeding, thermostat testing, radiator and fan service, and water-pump repair.

Schematics, Specifications, and Shop Notes

Particularly useful visual references include the PGM-FI system/component diagram, drivetrain control diagram, automatic-transmission hydraulic circuits, connector-location and harness-routing views, differential tooth-contact illustrations, and the full TRX680FA/FGA wiring diagram identified as drawing 0030Z-HN8-A600. Assembly drawings at the start of most sections give a fast view of component order before the detailed repair text.

The specification material is organized around the covered assemblies: standard and component torque tables, approved lubricant and capacity data, service limits, clearances, hydraulic pressure-test criteria, electrical test values, adjustment data, and lubrication/seal-point charts. This keeps the measurements tied to the actual inspection or repair procedure instead of presenting them as an isolated list.

Several warnings are especially relevant during repair planning. The throttle body is factory preset; disturbing its white-marked fasteners can cause a malfunction. An incorrect front-differential shim stack can bind or lock the gearset before the cover is fully tightened, and careless drive-shaft joint or stopper-ring handling can damage the differential or final-drive oil seals. Fuel-pressure tests, brake bleeding, transmission-pressure checks, running-engine diagnosis, and work with the ATV raised require adequate ventilation, eye protection around pressurized fluids, secure jack stands, and ignition-source control near fuel and battery work.