P1494

Tests 1 - 2:

Tests 3 - 7:

Tests 8 - 9:

SYMPTOM
P1494 - LEAK DETECTION PUMP SWITCH OR MECHANICAL FAULT

WHEN MONITORED
Immediately after a cold start, with ambient temperature between 40 °F and 90 °F and engine coolant temperature within 10 °F of ambient temperature.

SET CONDITION
The state of the leak detection pump switch is not in its expected state at key-on (engine not running). Or, following an engine start, a change in switch state is not seen when the LDP solenoid is energized to pull the pump diaphragm to its position

POSSIBLE CAUSES
- Fused ignition switch output circuit open
- LDP pressure switch circuit shorted to ground
- LDP switch sense circuit open
- LDP wiring and/or connectors observable defect
- LDP wiring harness intermittent failure
- Leak or obstruction in vacuum hose
- Leak detection pump defective
- PCM defective (LDP system)