Epson ET-8550 Error 100016: How to Check the Scanner FFC Cables and Connections

Question

Can you help me repair an Epson EcoTank ET-8550 that displays scanner error 100016? I am located in Hawaii and have been unable to find a local technician who can service this printer.

Answer

The Epson ET-8550 error 100016 is generally associated with the scanner system. In many cases, the printer cannot properly communicate with, detect, or initialize the scanner unit. The problem may be caused by a loose, damaged, incorrectly installed, or contaminated flat flexible cable, commonly called an FFC cable. It can also be caused by a scanner motor, scanner home-position sensor, mechanical obstruction, or an electronic problem involving the scanner control circuitry.

Start by Checking the Scanner FFC Cables

The first components I would inspect are the scanner FFC cables. The ET-8550 uses multiple flat cables to carry signals and power between the scanner assembly and the printer's main electronics.

You can view the Epson ET-8550 scanner three-cable FFC set [https://bchtechnologies.com/products/ffc-cable-for-epson-ecotank-et-8550-scanner-3-cable-combo-et8550?_pos=1&_sid=f3dde2209&_ss=r]. There is also a YouTube video on the product page showing the cables and providing visual guidance.

Before opening the printer, turn it off, disconnect the power cord, and allow it to sit unplugged for several minutes. The scanner cables are delicate, and working on the printer while it is powered can damage the mainboard, scanner board, cable contacts, or other electronic components.

Inspect each scanner FFC cable for the following problems:

• A cable that has partially pulled out of its connector

• A cable inserted crookedly or at an angle

• Exposed contacts facing the wrong direction

• A connector locking tab that is not fully closed

• Creases, folds, cuts, cracks, or burned areas on the cable

• Ink, moisture, corrosion, or residue on the cable contacts

• Darkened or missing conductive traces at the cable end

• Damage caused by repeatedly inserting and removing the cable

When reinstalling an FFC cable, make sure it is completely straight and evenly seated. Do not force it into the connector. Most FFC connectors use a small locking bar or hinged tab. The lock must be opened before inserting or removing the cable and then closed gently after the cable is fully seated.

If the locking tab is broken or the connector has lifted from the circuit board, replacing only the cable may not solve the 100016 scanner error. A damaged connector may require board-level repair or replacement of the affected circuit board.

Inspect the Scanner Mechanism

If the cables appear secure and undamaged, check whether the scanner carriage can move normally. The scanner carriage is the light bar located beneath the scanner glass.

With the printer unplugged, inspect the scanner area for:

• Packing material or tape left inside the scanner

• A foreign object blocking the scanner carriage

• A jammed or displaced scanner belt

• A disconnected scanner motor

• A damaged scanner carriage

• Dirt or ink contamination near the scanner home-position area

• A scanner light bar that is stuck away from its normal resting position

Do not force the scanner carriage aggressively. Scanner belts, gears, and plastic mounting components can be damaged easily. If the carriage is difficult to move, the obstruction or mechanical failure should be identified before applying additional force.

Watch the Scanner During Startup

If it is safe to do so after reassembly, observe what happens when the printer starts.

Normally, the scanner carriage should perform a short initialization movement. It may move away from its home position, illuminate, and then return to the starting area.

The printer's behavior can provide useful clues:

• No scanner movement or light: This may indicate a disconnected cable, damaged FFC cable, missing power, scanner board problem, motor failure, or mainboard problem.

• The scanner light turns on, but the carriage does not move: The scanner motor, drive belt, gear system, or motor cable may be faulty.

• The carriage moves briefly and then stops: The printer may not be detecting the scanner home position, or the carriage may be encountering resistance.

• The scanner makes repeated clicking or grinding sounds: A gear, belt, carriage guide, or home-position mechanism may be jammed or damaged.

• The scanner initializes normally, but error 100016 remains: There may be an intermittent cable connection, damaged signal trace, sensor fault, scanner electronics failure, or mainboard communication problem.

Check the Scanner Home-Position Detection

During startup, the printer needs to determine where the scanner carriage is located. If the scanner cannot find or confirm its home position, the printer may display error code 100016.

The home-position detection area may be affected by dirt, displaced parts, cable problems, or sensor failure. Carefully inspect the area where the scanner carriage normally parks. Make sure there is no debris or damaged plastic preventing the carriage from reaching its proper position.

Avoid applying cleaning liquids directly to sensors, cables, or electronic boards. Moisture can create additional short circuits or corrosion.

Consider Previous Repairs or Disassembly

If error 100016 appeared after the printer was opened, transported, converted, or repaired, a cable connection is especially likely.

Flat cables can look connected even when they are not inserted deeply enough. It is also possible to install a cable upside down or into the wrong connector. Compare the cable routing, contact orientation, and insertion depth with photographs or a repair video whenever possible.

Also check whether a cable was pinched under a cover or screw during reassembly. A cable may appear normal from above while one or more internal traces have been broken.

Replacing the Scanner Cable Set

If you find visible cable damage, replacing the scanner FFC cable set is a reasonable next step. Because the ET-8550 scanner assembly uses several related cables, replacing the complete set may be more practical than replacing only one cable, especially when the exact failed conductor cannot be identified visually.

After installing the replacement cables:

1. Confirm that every cable is routed without sharp bends.

2. Make sure the exposed contacts face the correct direction.

3. Verify that each connector lock is closed evenly.

4. Check that the cables are not trapped beneath the scanner housing.

5. Reassemble enough of the printer to prevent the cables from shifting.

6. Power on the printer and observe the scanner initialization.

Repeatedly powering the printer on while a cable is misaligned can create additional electrical damage. Therefore, carefully inspect all connections before testing.

When the Cables Are Not the Cause

If replacing or reseating the scanner cables does not clear Epson ET-8550 error 100016, the fault may be located in one of the following areas:

• Scanner motor

• Scanner home-position sensor

• Scanner carriage assembly

• Scanner drive belt or gears

• Scanner circuit board

• Mainboard scanner-control circuit

• Damaged connector on the scanner board or mainboard

• Broken circuit trace or solder joint

• Power supply line feeding the scanner assembly

At that stage, diagnosis may require voltage measurements, continuity testing, comparison with a working scanner assembly, or substitution of known-good parts. Replacing parts without confirming the failure can become expensive, especially if both the scanner assembly and mainboard are suspected.

Addressing printer issues can be complicated because many faults require hands-on inspection and testing. For that reason, we are unable to provide individualized remote troubleshooting, repair instructions, or ongoing technical support for printer repairs. We do offer an in-person printer evaluation and repair service [https://bchtechnologies.com/printer-repair-service] through our local diagnostic facility. Due to high demand, repairs are handled on a first-come, first-served basis, and it may take several weeks before an appointment or printer drop-off becomes available.

Our services can be arranged for either a complete printer or, in some cases, a specific removable component, with instructions provided for submitting the equipment. However, we understand that professional diagnostic and repair rates may not be the most economical option for every situation, particularly when shipping a printer from Hawaii would be required.

For this reason, we strongly encourage self-guided research when practical. You can begin with YouTube or visit the homepage of our BCH Technologies YouTube channel [https://youtube.com/@bchtechnologies]. On the channel page, use the search icon located near the "About" section to search for terms such as ET-8550 scanner cable, ET-8550 error 100016, ET-8550 FFC cable, or ET-8550 scanner removal.

We receive dozens of questions each day asking whether we have made a video about a particular repair. Since we have produced repair videos for more than nine years, it is difficult to remember every topic and video title. Using YouTube's channel-search function is usually the fastest way to locate the most relevant material. YouTube may also recommend helpful videos from other repair channels.

Thank you again for contacting BCH Technologies and for supporting our work. We hope the scanner cable inspection and the video on the product page help you identify the cause of error 100016 and determine the most practical repair option for your ET-8550.