EGR Control Solenoid: Description and Operation
DESCRIPTIONThe Electric EGR Transducer (EET) is a back pressure transducer combined with an electric vacuum solenoid. The vacuum solenoid receives its electrical signal from the Powertrain Control Module (PCM). Using this signal, the solenoid regulates the amount of vacuum allowed to flow through the solenoid and on to the transducer. The back pressure transducer measures the exhaust gas back pressure in the exhaust system and uses that reading to vary the strength of the vacuum signal applied to the EGR valve, thereby providing the proper amount of EGR flow for all operating conditions.
SOLENOID OPERATION
The PCM controls vacuum to transducer by providing solenoid ground. When the solenoid is energized, no vacuum reaches transducer. When the solenoid is de-energized, vacuum allowed to reach transducer.
The solenoid is energized (no vacuum to transducer), during engine warm-up, during Wide Open Throttle (WOT), during rapid acceleration/deceleration, or when the engine is at idle.
NOTE: If wiring is disconnected from solenoid EGR valve will operate at all times, affecting engine idle and performance.
BACK PRESSURE TRANSDUCER OPERATION
The transducer is a variable vacuum bleed valve controlled by exhaust system backpressure.
The transducer is supplied vacuum through the solenoid. When exhaust vacuum is great enough, the bleed valve closes completely. When backpressure is present but not great enough to close the bleed valve completely, and solenoid is de-energized, varying vacuum is applied to the EGR valve providing the correct amount of EGR to the engine for differing operating conditions.
CIRCUIT OPERATION
The Powertrain Control Module (PCM) operates the Exhaust Gas Recirculation (EGR) solenoid by providing a ground path on circuit K35. Circuit K35 connects to PCM cavity 35.
When the ignition switch is in the START or RUN position, it connects circuit A1 from fuse 3 in the PDC to circuit A21. Circuit A21 powers circuit F18 through fuse 9 in the fuse block. Circuit F18 supplies battery voltage to the EGR solenoid.