PACCAR MX (2004 Emissions) Fault Code: P1655 Yellow Warning – Short Circuit to Supply on ECU (D420) Pin (B4)

SET CONDITIONS:
This DTC is set when the ECU detects a higher voltage than expected on pin (B4) of PCI ECU (D420).

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

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
The DTC changes to inactive 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:
1. Wiring, short circuit to supply
2. Defective PCI ECU (D420)