PACCAR MX (2004 Emissions) Fault Code: P1204 Injector Solenoid Valve Cylinder 1 – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (A1)

PACCAR MX (2004 Emissions) Fault Code: P1204 Injector Solenoid Valve Cylinder 1 – Voltage Too High or Short Circuit to Supply on ECU (D420) Pin (A1)

SET CONDITIONS:
The PCI ECU (D420) detects a too high voltage or a short circuit to supply on the ECU pin A1 circuit.

DIAGNOSTIC CONDITION:
This diagnostic runs when the engine is running.

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected. To enable the injector output, the DTC must be cleared.

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:
Short circuit to supply in the circuit of ECU pin A1

ADDITIONAL INFORMATION:
The injector output is disabled by the PCI ECU when this DTC is detected. The output stays disabled until the DTC is cleared.