PACCAR MX (2004 Emissions) Fault Code: P1053 Speed Functions Off Switch – Data Erratic, Intermittent, or Incorrect

SET CONDITIONS:
The PCI ECU (D420) detects that both the variable speed limiter activation and deactivation switches are active at the same time.

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

POSSIBLE CAUSES:
Mechanical failure or damage to the variable speed limiter switches

ADDITIONAL INFORMATION:
The variable speed limiter allows the vehicle speed to be limited to a speed set by the driver.