SPN 925 FMI 5 code

Hello, i had a this code pop up on freightliner cascadia and i just cant figire it out. from the research ive done it goes to the backup alarm on the driver side firewall. i shorted the wire and a new code popped up: SPN 925 FMI 4. ive replaced the alarm itself and its still the same code as FM5. we dont have troubleshooting or diagrams im able to get at my shop as they refuse to get it

 

so i need to follow the #17 pin wire and see where it splits or leads cause the pin itself isnt corroded or messed up

 

idk, i tested continuity and its good, i checked both resistance and everything else is good. unless its broken somewhere and holding on by one gut wire or maybe it has something to do with a subbus switch cause theres a code for it too. i appreciate the help tho