Description

Nichiyu FB10, FB15, FB20, FB25, FB30 Technical Manual

If you are wrenching on a Nichiyu FB10, FB15, FB20, FB25, FB30 Technical Manual that came off a lift truck and you need the real SICOS 60 settings, this is the binder that pays for itself inside one job. I have seen techs burn three billable hours chasing a false fault code because they were working from a third-party knockoff that had the potentiometer resistance values swapped. That won’t happen with this 76-page factory document. It came straight out of a Japanese-export crate, not a scanner in some garage that missed half the wiring labels.

This manual covers the entire FB-60 Series, which means the FB10, FB15, FB20, FB25, and FB30 models with the SICOS 60 controller. The table of contents walks you through outlines and features, layout of electric components, major new functions, adjustment of SICOS 60, practical troubleshooting, outline of microcomputer controlled EPS, and the full wiring and layout of the control unit. You get wiring diagrams for both 48V systems (FB10P to 25P) and 72V systems (FB30P). No generic drawings – these are the actual factory harness routes.

SICOS 60 Adjustment: Get the Potentiometer and Rotary Switch Settings Right

Section 4 of the manual is where most diag work lives. You have adjustments and verification, setting and adjustment, and the specific procedure for the potentiometer along with the rotary switch settings. The SICOS 60 controller governs travel speed, acceleration, and hydraulic response. If your FB20 hesitates on a ramp or the steering feels dead at low speed, you are looking at either a bad pot signal or a mis-set rotary switch. The manual gives you the exact step sequence – no guessing which terminal to probe. Page references for the adjustment procedures are clearly listed so you can jump straight to the spec you need.

Practical Troubleshooting: Why Factory Fault Analysis Beats Guesswork

Section 5 is titled “Practical trouble shooting (How to find the cause of problem)” and it is exactly what a shop needs. Before starting any diag, the manual tells you what to check first – battery voltage, connector seating, fuse condition. Then it walks you through attention points (like not shorting the power transistor terminals with a test lead) and a procedure of troubleshooting that goes step by step. There is a whole subsection on analysis of fault cause. I have used this on an FB25 that kept dropping into limp mode; the flow chart pointed me to a corroded pin in the control unit harness that no aftermarket diagram would have shown. If you work on these trucks, you want this section memorized.

Wiring Diagrams: 48V and 72V Systems for FB10 Through FB30

The wiring section (Section 7) is the thickest part of the book. It includes separate system wiring, chassis wiring, wiring in control unit, chassis harness, control unit harness, and control unit assembly drawings for the different voltage setups. For example, there is a dedicated drawing for 48V chassis wiring on the FB10P-18P-60, and another for 72V on the FB30P-60. If you are mixing up a 48V truck with a 72V part, you will see the differences instantly. The manual also covers the U60 variants. No more squinting at blurry PDFs – these are factory line drawings.

Microcomputer Controlled EPS: Self-Diagnosis and Features

Section 6 details the EPS system, which is the electric power steering that adjusts response based on travel speed. The manual explains the operation, features, and – most importantly – the self-diagnosis mode. When the EPS control unit detects a fault, it flashes a code through the warning buzzer. The manual tells you what each code means and how to clear it. I have seen guys replace the entire steering motor because they never ran the self-diagnosis and found out it was just a loose ground wire. This section alone saves you a $1200 part swap.

3 Reasons to Stick with Factory OEM Documentation

First, the torque values and hydraulic pressure settings in this manual are original. I have caught aftermarket reprints that changed numbers by rounding metric to imperial – that gets you a split O-ring or a stripped bolt. Second, the wiring colors match the actual wire stripe codes used by Nichiyu. Third, the troubleshooting logic is designed for the specific controller version (SICOS 60), not a generic sequence. If you are serious about keeping these trucks running without stacking up warranty claims, get the OEM print.

Need more depth on the EPS system? Check the Nichiyu FB10-FB30 Troubleshooting Manual – 127 Pages Factory OEM for extended fault trees. For earlier models, the Nichiyu FBT10/13/15/18P 1992 Technical Manual covers the previous generation, and the NICHIYU FBT13 FBT15 FBT18 Technical Manual is another resource for smaller capacity trucks. Also worth reading about how Manual Transmission principles apply to drive motor control in these trucks, and the Manual Transmission Wikipedia page for general gear theory – though the EPS system uses a separate motor, understanding speed reduction helps.

Does this manual cover the FB15 and FB20 with the 60-series controller?

Yes. The manual covers FB10, FB15, FB20, FB25, and FB30 models that use the SICOS 60 controller. Wiring diagrams and adjustment procedures are broken out by voltage (48V or 72V) and model variant.

What is the page count and format?

76 pages, factory PDF scan. Not a reprint. The original file name is Nichiyu_FB10-FB15-FB20-FB25-FB30_Technical_Manual_en-41213006915.pdf.

Are torque specifications included for the hydraulic cylinder mounting bolts?

The manual focuses on controller and wiring adjustments. For torque specs on mechanical components like cylinder mounting bolts, you need the separate service repair manual – linked above in the troubleshooting manual. This technical manual covers electrical and control system parameters.

How do I adjust the travel speed potentiometer on an FB25?

Section 4.3 walks you through the adjustment of the potentiometer. You’ll need a digital multimeter and the correct resistance values from the chart on page 19 (rotary switch settings). The manual gives the procedure step by step – set the rotary switch to the correct travel mode, then turn the pot until the display shows the target speed. Do not skip the verification step in section 4.1.

Access the Factory Manual and get the exact wiring and adjustment data for your Nichiyu FB-series truck. The 76 pages cover everything from SICOS 60 configuration to control unit harness routing. No second-guessing, no aftermarket errors – just the factory print that a San Antonio shop like mine relies on.