Fixing the SPN 677 FMI 12 Starter Relay Fault
Seeing spn 677 fmi 12 pop up on your diagnostic screen is never the way you want to start your workday, especially when you've got a schedule to keep and a load to move. It's one of those codes that feels like a gut punch because it directly involves the starting system. If the truck won't crank, you aren't going anywhere. This specific fault is usually telling you that your Engine Control Module (ECM) has detected an internal failure or a serious logic error with the starter lockout relay circuit. ...