J1939 Voltage Drop – A Field Test That Cuts Diagnostic Time from 7.5 Hours to 20 Minutes
Estimated reading time: 12 minutes January 2025, Edmonton. A fleet manager with 23 trucks called after three shops failed to fix a 2022 Kenworth T680. Symptom: intermittent SPN 639 FMI 9, transmission ECU offline after 20 minutes of driving. First shop replaced the transmission ECU ($2,800). Second replaced the dash cluster and reflashed ($1,900). Third […]