Toyota 42-6FGCU15, 42-6FGCU18, 42-6FGCU20, 52-6FGCU20, 42-6FGCU25, 52-6FGCU25, 42-6FGCU30, 52-6FGCU30 Forklift Service Manual (P/N CU015-C)

• Coverage and file set: 355 PDF pages total—a 331-page Toyota Motor Corporation service publication for 42-6FGCU15, 42-6FGCU18, 42-6FGCU20, 52-6FGCU20, 42-6FGCU25, 52-6FGCU25, 42-6FGCU30, and 52-6FGCU30, plus supplemental wiring booklets CE012 (10 pages), CU021 (6 pages), and CU020 (8 pages).
• Engine and configuration identification: The covered trucks are gasoline, torque-converter models. The listed 42-series applications use Toyota's 4Y engine; the 52-series applications use the GM4-181. Frame-number locations and formats help confirm the machine before parts or repair procedures are selected.
• Engine-related chassis service: Covers engine removal and installation, engine-speed adjustment, air-cleaner and clogging-warning checks, radiator service, standard and optional catalytic mufflers, battery inspection, starter and alternator removal, belt adjustment, and accelerator-pedal setup. Internal engine overhaul is outside this manual; Toyota directs technicians to 4Y manual No. CE602 and GM4-181 manual No. CU629.
• Torque converter and transmission: Provides separate 1-ton-series and 2-/3-ton-series hydraulic circuits, symptom-based troubleshooting, control-valve and torque-converter oil-pump service, transmission and clutch-shaft disassembly/inspection/reassembly, shift-lever and inching adjustment, stall testing, and operating-pressure checks.
• Differential, axles, steering, and brakes: Details differential removal and overhaul, front hub and axle-shaft service, rear axle and steering-knuckle work, rear axle-cylinder repair, EATON hydrostatic steering-control overhaul and relief-pressure testing, front-brake service, master-cylinder repair, brake bleeding, parking-brake setup, and brake-pedal adjustment.
• Material-handling hydraulics, mast, and cylinders: Includes system testing, 4Y- and GM-specific oil-pump service, oil-control-valve repair and adjustment, full V-mast removal and teardown, chain and fork inspection, FV/FSV mast adjustment, lift-cylinder rod shimming, lift and tilt cylinder repair, and flow-regulator and safety-down-valve service.
• Factory reference material: Supplies component-specific torque tables, lubricant and fluid-capacity data, inspection limits, clearances, maintenance and replacement schedules, an SST list with Toyota tool numbers, exploded component views, hydraulic circuit diagrams, and a 4Y/GM wiring diagram.

Coverage and Engine Scope

Toyota dates the main service information to July 1995 and notes that later design changes may be covered by subsequent Parts & Service News.

The three add-on wiring booklets are not exact substitutes for the main publication's 42/52-6FGCU15-30 electrical coverage. CE012 applies to 6FG/6FD10-30 models, CU021 to 52-6FGCU33/35/45, and CU020 to 52-6FGU33/35/40/45, 02-6FDU33/35/40/45, 52-6FGAU50, and 02-6FDAU50. For the advertised trucks, use the 4Y/GM wiring diagram contained in the 331-page publication.

The manual concentrates on forklift chassis, drivetrain, hydraulics, mast assemblies, and related electrical service. Its maintenance chart calls out valve-clearance and compression checks, but detailed internal engine specifications and overhaul procedures remain in CE602 or CU629 and are not included in this PDF.

Specifications and Diagnostic Data

The torque-converter chapter is one of the strongest diagnostic sections. Separate troubleshooting tables for the 1-ton and 2-/3-ton designs address loss of drive, weak tractive effort, delayed engagement, shift shock, overheating, abnormal noise, and oil leakage. The measurement section covers stall speed and the main, clutch, converter, lubrication, and inching circuits, tying repair decisions to test results before teardown.

Capacity-series differences continue elsewhere. Front-brake and rear axle-cylinder procedures are separated for the 1-ton and 2-/3-ton designs. Differential coverage includes carrier removal, ring-gear and pinion inspection, bearing adjustment, and front hub work; the brake chapters add master-cylinder overhaul, system bleeding, braking-force checks, and parking-brake and pedal adjustment.

Hydraulics, Mast, and Shop Reference

Material-handling diagnosis includes natural-drop, forward-tilt, and cylinder leakage tests. Pump and control-valve chapters add removal, internal inspection, operational testing, and pressure adjustment. The oil-control-valve section warns that careless relief adjustment can produce pressure high enough to damage the pump or other hydraulic components.

Mast coverage distinguishes the V, FV, and FSV configurations. The V-mast section includes removal and full disassembly; the FV and FSV sections focus on component layouts, roller and mast adjustment, and lift-cylinder rod shimming. The manual also warns against incorrect mast side-roller orientation and against dry hydraulic-cylinder reassembly, where seals and sliding parts can be damaged.

Useful visual references include the 1-ton and 2-/3-ton torque-converter hydraulic circuits, the brake hydraulic circuit, the material-handling hydraulic system diagram, V/FV/FSV mast and cylinder exploded views, and the 4Y/GM electrical wiring diagram. Listed SSTs include the engine unit hanger 09010-20111-71, torque-converter clutch-drum spring tool 09220-22000-71, inner mast stopper 09610-22000-71, and cylinder-cap remover/replacer 09620-10100-71.

Forklift repair involves suspended components, stored hydraulic pressure, brake systems, and heavy mast assemblies. Follow the manual's support, hoisting, pressure-release, and isolation precautions, and use a qualified technician when the work exceeds the available training or equipment.