How does a leak detection pump work in a car?
Function. A leak detection pump (LDP) utilizes engine vacuum to help detect leaks. The LDP has a diaphragm that changes in shape as pressure in the vacuum rises. When the right level is reached, the LPD shuts off which also prevents any more buildup in the vacuum. The Powertrain Control Module…
How does the leak detection system ( LDP ) work?
The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. During self-diagnostics, the Powertrain Control Module (PCM) first checks the Leak Detection Pump (LDP) for electrical and mechanical faults.
What happens when the diaphragm is down on a leak detection pump?
When the diaphragm is down, the switch is closed, which sends a 12 V (system voltage) signal to the PCM. When the diaphragm is up, the switch is open, and there is no voltage sent to the PCM.
How does an EVAP leak detection switch work?
If the first checks pass, the PCM then uses the LDP to seal the vent valve and pump air into the system to pressurize it. If a leak is present, the PCM will continue pumping the LDP to replace the air that leaks out. The PCM determines the size of the leak based on how fast/long it must pump the LDP as it tries to maintain pressure in the system.
What does the leak detection pump do on a car?
The leak detection pump is the component that often triggers those “Check Engine” warning lights when it detects small leaks that would be hard to see.
The leak detection system tests for EVAP system leaks and blockage. It also performs self-diagnostics. During self-diagnostics, the Powertrain Control Module (PCM) first checks the Leak Detection Pump (LDP) for electrical and mechanical faults.
When the diaphragm is down, the switch is closed, which sends a 12 V (system voltage) signal to the PCM. When the diaphragm is up, the switch is open, and there is no voltage sent to the PCM.
How does the PCM work on a leak detection pump?
Based on reed switch input, the PCM de-energizes the LDP solenoid, causing it to block the vacuum port, and open the atmospheric port. This connects the upper pump cavity to atmosphere through the EVAP air filter. The spring is now able to push the diaphragm down.