PACCAR MX (2004 Emissions) Fault Code: P3421 MX Engine Brake Solenoid Valve Cylinder 3 – Current Too Low or Open Circuit on ECU (D420) Pin (A24)
PACCAR MX (2004 Emissions) Fault Code: P3421 MX Engine Brake Solenoid Valve Cylinder 3 – Current Too Low or Open Circuit on ECU (D420) Pin (A24)
SET CONDITIONS:
This DTC is set when the PCI ECU (D420) detects a too low current on the control circuit for engine brake activation.
DIAGNOSTIC CONDITION:
This diagnostic runs during activation of the engine brake.
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. Open circuit in the engine brake control wiring
2. Malfunction of the engine brake solenoid
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