PACCAR MX (2004 Emissions) Fault Code: P1122 Cruise Control Brake Signal – Data Erratic, Intermittent, or Incorrect

PACCAR MX (2004 Emissions) Fault Code: P1122 Cruise Control Brake Signal – Data Erratic, Intermittent, or Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that both cruise control and engine torque are governed and at the same time the parking brake or foot brake pedal is applied.

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

CORRESPONDING OBD READINESS MONITOR:
None

RESET CONDITION:
This DTC changes to inactive when the fault is no longer detected.

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

ADDITIONAL INFORMATION:
1. When cruise control is activated, the PCI ECU governs the engine torque to meet or maintain the cruise control target speed.
2. Cruise control can no longer be activated when this DTC is active.