DSM/ECU/Reverse Engineering

Example

Here is an example of record keeping of the components and PCB references I did on a 1.8l ECU I reversed as practice:

Exterior

• 
  ECU top
• 
  ECU Exterior, Side

Top

 MD159561
 E2T33674E
  0607
 Mitsubishi Electric Corp.
 Japan

Side

 9561
 E2T33674E
 Mitsubishi Electric Corp.
 Japan

Interior

EPROM

• E924

PCB

• DSM/ECU/JE331B988B

• 
  Copper traces of PCB
• 
  Silkscreen
• 
  Top layer photo
• 
  Bottom layer photo

How-To

Hardware

1. Obtain ECU
2. Take external photographs
   • Mostly for all the numbers and letters/the stickers
3. Open ECU
4. Remove PCB
5. TAKE MORE PICTURES (before you touch anything else)
   • The code on the plug socket
   • The microprocessor
   • The EPROM (if there is one)
   • Any and all visible marking on components
   • The ENTIRE board on BOTH sides
6. RECORD all components with visible markings, decode resistor values
   • This means a table with the PCB Silkscreen references and the components values
7. ACETONE bath
   • This is to remove all the conformal coating junk that interferes with reading markings AND the ability to probe, test, and desolder
8. SCRUB with Toothbrush, Q-Tips
9. PHOTOGRAPH and RECORD any newly visible information
10. REMOVE any components with known values:
    1. Electrolytic capacitors can go first
    2. Then any ICs
    3. Resistors with the bands already decoded
    4. Connectors
11. REMOVE components with unknown values ONE AT A TIME
    1. SMD Capacitors and Transistors are good examples
    2. Remove one, use the Multimeter and/or LCR meter to get values and RECORD them in the table
12. Eventually you will be left with a BARE BOARD
13. SPRAY and WIPE DOWN the bare PCB with WD-40 to clean up any remaining conformal coating and junk
    • This preps the board for nice clear photographs
14. PHOTOGRAPH both sides of the PCB
    • Get ONE photo of EACH side of the PCB
    • Flat
    • In focus
    • Dead-on photos with no perspective error
    • Use a tripod
    • Use lighting
    • Use a remote shutter-release to eliminate shake from the image

Digitization

1. Do color correction in darktable
2. Import to GiMP and isolate the Silkscreen to generate a silkscreen layer
3. Import into Inkscape to create a vector of the copper traces
4. Use the last two steps to import into KiCad
   • Recreate the PCB
   • Create a schematic from the PCB

Result

1. A BOM of sorts
   • List of all the components, and their values and locations on the PCB
2. A Schematic of the electrical connections
3. A PCB layout
4. Lots of photos

Toolbox

Tools

• Screwdrivers
• Tweezers
• Solder
• Solder Sucker
• Solder Wick
• Soldering Iron
• SMD/Reflow Air Tool
• Chamois cloth
• Multimeter
• LCR Meter

Solvents

• Acetone
• 99% Isopropyl alcohol
• WD-40
• Flux
• Flux cleaner
• H2O

Camera

• DSLR
• Tripod
• Circular-polarized lens
• Remote shutter-release
• Lighting

Software

• Darktable
• GiMP
• Inkscape
• KiCad