Programming a replacement blade key (TOY47 profile, 4D transponder) for a 2008 Toyota Yaris with all keys lost cannot be performed directly over the OBD port. The job requires removing the immobilizer module and writing key data via dump mode.

Procedure & Technical Findings

1. Module Removal:Access the correct immobilizer box located behind the dashboard. Note that two similar control units exist in the vehicle, and accessing the primary immo box requires pulling the dash.
2. EEPROM Data Extraction:Desolder the Atmel 8-pin EEPROM chip from the PCB and read the dump data using a bench programmer.
3. Transponder Generation:Standard Xhorse VVDI Super Chip XT27A and XT27B chips may fail to register. Use an VVDI XT57B Super Chip to generate one of the key slots retrieved from the dump.
4. Data Write-Back:Crucial Step: Write the modified EEPROM dump containing the newly added key back to the Atmel memory chip before resoldering it to the board. Attempting to start the car without reflashing the EEPROM will prevent ignition.
5. Reassembly & Testing:Resolder the IC back onto the board and reinstall the immobilizer unit. If the vehicle fails to start on the first crank, cycle the ignition twice to initialize the transponder link.