PACCAR MX (2004 Emissions) Fault Code: P1223 Injector Solenoid Valve Cylinder 4 – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A12)

PACCAR MX (2004 Emissions) Fault Code: P1223 Injector Solenoid Valve Cylinder 4 – Voltage Too Low or Short Circuit to Ground on ECU (D420) Pin (A12)

SET CONDITIONS:
The PCI ECU (D420) detects a too low voltage or a short circuit to ground on the ECU pin A12 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:
1. Short circuit to ground in the circuit of ECU pin:
– A12 or
– A4 or
– A8
2. Faulty injector 4 or 5 or 6

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.