Leak Detection Pump SW or Mechanical Fault

Name of Code:
Leak Detection Pump Pressure Sw

When Monitored:
Immediately after a cold start with ambient temperature between 40° F and 90° F and coolant temperature within 10° F of ambient temperature.

Set Condition:
The atate of the switch does not change when the solenoid is energized.

Theory of Operation:
The leak detection pump pressurize the evap system. To determine whether the system is intact or has a leak, a switch is located on the pump shaft. As the pump moves up and down the switch opens and closes a 12-volt circuit to the PCM. If the evap system is intact, eventually the switch will stop breaking the circuit as the system is pressurized. If there is a leak the switch will continue to open end close the circuit. The PCM determines the size of the leak by watching how long it takes the switch to change state, after the solenoid is turned off.

Possible causes:
- Open or shorted LDP switch sense circuit
- Leak detection pump switch failure
- Open fused ignition switch Output
- Manifold vacuum source
- PCM failure
- Connectors
- Wires