MIL on. DTCs are stored in the engine control module (ECM). Drivability is not affected. The leak detection pump (LDP) is a vacuum-driven, ECM-controlled, diaphragm pump. In order for the LDP to operate, the engine must be running and vacuum must be applied to the vacuum switch on the LDP. The LDP pressurizes the EVAP system and monitors any pressure drop within a specified amount of time in order to detect a leak.
