Vacuum Pump Explanation

ELECTRIC VACUUM PUMP DESCRIPTION
On the 3.6L engine there is an electric vacuum pump (Fig 1) #2 located on the frame bracket behind the left side of the bumper. The vacuum pump (Fig 1) #2 has one electrical connector (Fig 1) #4 on a pigtail, a vacuum hose (Fig 1) #1 with a quick-connect type end, and a vent hose (Fig 1) #3. The vacuum pump (Fig 1) #2 mounts with two rubber insulated studs to reduce vibration.

ELECTRIC VACUUM PUMP OPERATION
The Electric Vacuum Pump (EVP) system is installed to provide supplemental vacuum to the brake booster when the engine vacuum supply is low. The vacuum pump is connected to the engine and the brake booster through a series of hoses and one-way flow check valves. A pressure senor, mounted in the brake booster, provides information to the Antilock Brake System (ABS) module, then the vacuum level is sent over CAN to the Powertrain Control Module (PCM). The PCM modulates the EVP operation to maintain the brake booster vacuum within a given range. This system ensures that the customer experiences a consistent brake pedal feel under all driving conditions.

A two wire electrical connector is used to supply power and ground for the vacuum pump. Operating voltage is between 9V - 16V. Control of the vacuum pump is provided by the Powertrain Control Module (PCM) using a low side driver to a normally open relay (coil side). The relay coil side power is from a fuse in the under hood PDC. The switched power circuit to the vacuum pump relay is wired directly from the battery through an inline fuse holder located below the remote battery post connection on the RH side in the engine compartment. The relay is located on the LH shock tower in the engine compartment.

The PCM monitors the Manifold Absolute Pressure (MAP) sensor and when the signal indicates low engine vacuum the PCM will cycle the vacuum pump as necessary to add vacuum to the power brake booster. The vacuum hoses are connected between the vacuum pump, the engine manifold (for MAP sensor signal), and the power brake booster vacuum sensor (on the brake booster). When the PCM cycles the vacuum pump on, the PCM monitors the MAP sensor and if the vacuum signal does not indicate a rising vacuum then DTCs will be set. Additionally, the Antilock Brake System (ABS) module monitors the vacuum at the brake booster vacuum sensor and DTCs will also set in the ABS module.

ELECTRIC VACUUM PUMP REMOVAL
1. Remove the bumper filler panel fasteners (Fig 1) #1 and slide the bumper filler panel (Fig 1 ) #2 to the RH side enough to expose the vacuum pump.
2. Disconnect the electrical connector (Fig 1) #3, behind and at lower end of pump.
3. Release the locking tab (Fig 3) #6 and disconnect the quick connect vacuum hose (Fig 3) #1,# 2 from the vacuum pump (Fig 3) #4.
4. Disconnect the vent hose (Fig 3) #5 from the vacuum pump #4.
5. Remove the vacuum pump retaining nuts (Fig 3) #2 and remove the vacuum pump #4 from the vehicle.

ELECTRIC VACUUM PUMP INSTALLATION
1. Position the vacuum pump (Fig 3) #4, install the mounting nuts #2 and torque to 55 N.m (41 ft. lbs.).
2. Connect the electrical connector (Fig 3) #3.
3. Connect the quick-connect vacuum hose (Fig 3) #1, #6 to the vacuum pump #4 and seat the locking tab (Fig 3) #6.
4. Position the bumper filler panel (Fig 2) #2 and install the fasteners (Fig 2) #1.