P1494 Leak Detection Pump Switch or Mechanical Fault

SYMPTOM
P-1494 LEAK DETECTION PUMP SW OR MECHANICAL FAULT

WHEN MONITORED
After a cold start, with ambient temp between 40 and 90 degrees F and the coolant temp within 10 degrees F of ambient temp.

SET CONDITION
The LDP switch is not in its expected state when engine is not running. After an engine start a change in switch state is not seen when the LDP solenoid is energized to pull the pump diaphram to the up position.

POSSIBLE CAUSES
- Fused ignition switch out circuit open
- LDP pressure switch circuit short to ground
- LDP switch sense circuit open
- LDP wiring and/or connectors obs def
- LDP wiring harness intermittent failure
- Leak or obstruction in vac hose
- Leak detection pump defective
- PCM def (LDP system)