No. Firmware updates are separate and available from Yaesu. The service manual covers only hardware.
The manual is highly detailed, offering a comprehensive look at the radio's "under the hood" components: yaesu ft-891 service manual
Let’s walk through a common repair scenario: yaesu ft-891 service manual
The owner’s manual handles this (SWR, antenna, power settings). Once those are ruled out, open the service manual. yaesu ft-891 service manual
: Instructions for adjusting the reference frequency, TX/RX gain, and carrier levels to keep the radio within factory specifications.
Unlike older analog radios, many "repairs" for the FT-891 are actually resolved via firmware updates. The service manual references the bootloader procedure. Always check the installed firmware version in the menu against the latest version on the Yaesu website before diving into hardware.