Description

Komatsu 70ES-6 1999 Service Manual – What the Factory Printed

If you’re working on a Komatsu 70ES-6 1999 Service Manual and reach for a third-party PDF, you’re guessing. Guessing on a 70ES-6 means a misaligned swing circle, a brake valve that leaks down overnight, or a transmission that shifts hard. I’ve seen it. This 625-page OEM book from July 1999 is the only document Komatsu authorized for its dealers. It’s what I use when a 70ES-6 rolls into my shop with a hydraulic drift or a governor code.

The structure is laid out so you can find real data fast. 10 Structure and Function breaks down every major assembly: engine related parts, radiator and oil cooler, power train, swing circle, transmission, axle, suspension lock cylinder, braking train, brake pedal, brake valve, accumulator, steering train, steering column, hydraulic circuit diagram, hydraulic tank, pump, control valve, CLSS, swing motor, center swivel joint, travel motors, PPC valves, safety lock valve, EPC and solenoid valves, and the full hydraulic cylinder and work equipment sections. That’s not a table of contents you get from a reprint; it’s the factory’s order of assembly.

Engine and Transmission Diagnostics: Real Specs, Not Guesses

Section 20 Testing and Adjusting starts with a Table of Judgement Standard Value and a Standard Value Table for Electrical Parts. You need the governor motor lever stroke? It’s in there. Hydraulic pressure in the work equipment, swing, and travel circuits? Test procedure and adjustment specs are listed. The Manual Transmission section in this manual covers the exact gear ratios and shift pressures for the 70ES-6. Don’t use aftermarket data; the factory tolerances are different from third-party sources. I’ve had a transmission fail because someone used generic viscosity specs. This book gives you the OEM numbers.

Suspension Lock Cylinder and Brake Valve: Factory Torque Data

The suspension lock cylinder section (page 1 O-14 in the original pagination) includes the assembly sequence and the hold-check procedure. The brake valve section (1 O-18) gives you the clearance specs and the bleeding order. If you skip the order on a Komatsu brake valve, you’ll trap air and lose pedal feel. Every torque value in this manual was measured at the factory. No generic inch-pound conversions.

Troubleshooting the Governor and Pump Controller

This manual devotes dozens of pages to the governor/pump controller (E-Mode) troubleshooting. It covers E-1 through E-12: power source issues, fuel control dial input abnormality, motor drive disconnection and short circuit, feedback potentiometer failure, battery output short, motor step-out, engine not starting, irregular idling, lack of output, engine not stopping, and defective battery relay. Each fault has a judgement table, an electrical circuit diagram, and a step-by-step procedure. The service code table is included so you can cross-reference monitor panel codes directly to the fix. No guesswork.

Is This Manual Right for Your Shop?

If you own a 70ES-6 or repair them regularly, yes. Home garage enthusiasts who take on big jobs like a swing motor rebuild or a hydraulic pump swap need this level of detail. The manual assumes you have basic tools, but it doesn’t skip the specialty steps like bleeding the PPC accumulator or setting the LS differential pressure. Beginners should read the “Points to Remember When Troubleshooting” section before touching any connector. Safety warnings are printed in bold — heed them.

What the 20 Testing Section Covers

Section 20 includes: checking and adjusting A/C compressor belt tension, adjusting engine speed sensor, testing governor motor lever stroke, testing swing circle bearing clearance, testing hydraulic pressure in work equipment/swing/travel circuit, testing and adjusting TVC valve output pressure, LS valve output pressure and LS differential pressure, PPC pressure, EPC valve solenoid output pressure, measuring PPC valve output and testing PPC shuttle valve, adjusting work equipment-swing PPC valve, testing location causing hydraulic drift, measuring oil leakage, releasing remaining pressure, bleeding air, and accumulator procedures. Each test has a specification table. Use the factory numbers, not aftermarket approximations. A Manual Transmission rebuild on this machine requires the gear backlash and shim thickness from this book — nothing else matches.

Source Validity: OEM Print vs. Aftermarket Copies

This is a direct scan of the original Komatsu publication, UEBM000500, dated July 1999. Serial numbers PIN1 70ES-6 -K30001 and up. The copyright belongs to Komatsu America International Company. Aftermarket manuals often omit the brake valve section or the CLSS hydraulic circuit diagram because they scan poorly. This copy has all three electrical wiring diagram pages, the full connector pin connections table, and the hydraulic circuit diagram. If you rely on a reprint, you risk missing a warning about accumulator pre-charge pressure. I’ve seen that mistake put a tech in the ER.

Does this manual cover the electrical wiring diagrams?

Yes, three full pages of wiring diagrams are included, plus connector pin tables and the machine monitor system.

What about troubleshooting the engine control system?

The manual includes the entire S-Mode troubleshooting section: starting performance poor, engine does not start (cranks but no exhaust, or doesn’t crank), irregular idling with hunting, lack of output (high idle too low), engine does not stop, and defective battery relay operation. Each fault has a judgement chart, electrical circuit diagram, and a procedure that walks through voltage checks, resistance checks, and component tests. The service code table gives you exact codes for every sensor and actuator. You also get the method of using troubleshooting charts and the sequence of events so you don’t waste time chasing a symptom.

This is the same book that Komatsu dealers used when these machines were new. If you want to fix your 70ES-6 without farming it out to the dealer, get the factory data. Access the Factory Manual now and keep it on your bench — next to your torque wrench.

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