Need help with Couple codes

Detroit codes are 2 digits. SPN (Suspect Parameter Number) are 2 - 4 digits and FMI (failure mode indicator) are 1 or 2 digits.
SPN and FMI go together. You only list SPN 639 with no FMI. The 521860 is not correct.


Here is a link for SPN 639
I have code spn 639 Fmi 2 on a 2015 frl Cascadia dd15. Freightliner Cascadia 2015 Detroit. Haven’t tried anything (justanswer.com)

 

In a New Cascadia for example, SPN 521860 fault is for your windshield washer pump. Should also have a FMI of 4, 5 or 6 with that. You might inspect pins for corrosion at pump. With unplugged from harness try powering pump with power probe for example. If pump runs, then suspect your wiring and inspect your for chaffing or corrosion.

 

In a New Cascadia SPN 520197 has only one FMI and that is 31. Error description is "sSAM detected problem with MQ switch bus."
For example, for your Hazard lights to work, under normal conditions, when you press the Hazard lights button a message is sent over the Message Que (MQ)-bus to the integrated modular switch field (MSF) in the Single Signal and Actuation Module (sSAM). On the New Cascadia the Hazard light switch is the Primary Subordinate Module. It appears these switches use 3 wires to connect that are daisy chained together from the primary subordinate module to the secondary subordinate modules. It would appear you need Diagnostic Link and to look at the Instrumentation Panel to troubleshoot this.