PACCAR MX (2004 Emissions) Fault Code: P0480 Electronically Controlled Fan – Current Too Low or Open Circuit on ECU (D420) Pin (C74)

SET CONDITIONS:
The PCI ECU (D420) detects a too low current on the control circuit of the electronically controlled fan clutch (B335) for more than 25 seconds.

DIAGNOSTIC CONDITION:
The diagnostic runs continuously when the ignition is keyed on.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive 45 minutes after the diagnostic runs and passes.

REPAIR VERIFICATION:
1. Clear all DTCs.
2. Test drive or operate the vehicle to meet the diagnostic conditions and set conditions.
3. Did the DTC come back?
– No, repair successful
– Yes, repair unsuccessful

POSSIBLE CAUSES:
Open circuit in the control circuit of the electronically controlled fan clutch (B335) caused by:
1. Wiring issues between ECU (D420) and the electronically controlled fan clutch (B335).
2. Malfunction in the electronically controlled fan clutch (B335).